brotli/enc/

brotli_bit_stream.rs

#![allow(unknown_lints)]
#![allow(unused_macros)]

use core::cmp::{max, min};
#[cfg(feature = "std")]
use std::io::Write;

use super::super::alloc::{Allocator, SliceWrapper, SliceWrapperMut};
use super::super::dictionary::{
    kBrotliDictionary, kBrotliDictionaryOffsetsByLength, kBrotliDictionarySizeBitsByLength,
};
use super::super::transform::TransformDictionaryWord;
use super::super::{alloc, core};
use super::block_split::BlockSplit;
use super::combined_alloc::BrotliAlloc;
use super::command::{Command, GetCopyLengthCode, GetInsertLengthCode};
use super::constants::{
    kCodeLengthBits, kCodeLengthDepth, kCopyBase, kCopyExtra, kInsBase, kInsExtra,
    kNonZeroRepsBits, kNonZeroRepsDepth, kSigned3BitContextLookup, kStaticCommandCodeBits,
    kStaticCommandCodeDepth, kStaticDistanceCodeBits, kStaticDistanceCodeDepth, kUTF8ContextLookup,
    kZeroRepsBits, kZeroRepsDepth, BROTLI_CONTEXT_LUT, BROTLI_NUM_BLOCK_LEN_SYMBOLS,
    BROTLI_NUM_COMMAND_SYMBOLS, BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS, BROTLI_NUM_LITERAL_SYMBOLS,
};
use super::context_map_entropy::{speed_to_tuple, ContextMapEntropy, SpeedAndMax};
use super::entropy_encode::{
    BrotliConvertBitDepthsToSymbols, BrotliCreateHuffmanTree, BrotliSetDepth,
    BrotliWriteHuffmanTree, HuffmanComparator, HuffmanTree, SortHuffmanTreeItems,
};
use super::histogram::{
    ContextType, HistogramAddItem, HistogramCommand, HistogramDistance, HistogramLiteral,
};
use super::input_pair::{InputPair, InputReference, InputReferenceMut};
use super::interface::StaticCommand;
use super::static_dict::kNumDistanceCacheEntries;
use super::util::floatX;
use super::{find_stride, interface, prior_eval, stride_eval};
use crate::enc::backward_references::BrotliEncoderParams;
use crate::enc::combined_alloc::{alloc_default, alloc_or_default, allocate};
use crate::VERSION;

pub struct PrefixCodeRange {
    pub offset: u32,
    pub nbits: u32,
}
pub const MAX_SIMPLE_DISTANCE_ALPHABET_SIZE: usize = 140;

fn window_size_from_lgwin(lgwin: i32) -> usize {
    (1 << lgwin) - 16usize
}

struct CommandQueue<'a, Alloc: BrotliAlloc + 'a> {
    mb: InputPair<'a>,
    // TODO: delete unused fields
    #[allow(dead_code)]
    mb_byte_offset: usize,
    mc: &'a mut Alloc,
    queue: <Alloc as Allocator<StaticCommand>>::AllocatedMemory,
    pred_mode: interface::PredictionModeContextMap<InputReferenceMut<'a>>,
    loc: usize,
    entropy_tally_scratch: find_stride::EntropyTally<Alloc>,
    best_strides_per_block_type: <Alloc as Allocator<u8>>::AllocatedMemory,
    entropy_pyramid: find_stride::EntropyPyramid<Alloc>,
    context_map_entropy: ContextMapEntropy<'a, Alloc>,
    #[allow(dead_code)]
    stride_detection_quality: u8,
    #[allow(dead_code)]
    high_entropy_detection_quality: u8,
    block_type_literal: u8,
    #[allow(dead_code)]
    best_stride_index: usize,
    overfull: bool,
}

impl<'a, Alloc: BrotliAlloc> CommandQueue<'a, Alloc> {
    fn new(
        alloc: &'a mut Alloc,
        num_commands: usize,
        pred_mode: interface::PredictionModeContextMap<InputReferenceMut<'a>>,
        mb: InputPair<'a>,
        stride_detection_quality: u8,
        high_entropy_detection_quality: u8,
        context_map_entropy: ContextMapEntropy<'a, Alloc>,
        best_strides: <Alloc as Allocator<u8>>::AllocatedMemory,
        entropy_tally_scratch: find_stride::EntropyTally<Alloc>,
        entropy_pyramid: find_stride::EntropyPyramid<Alloc>,
    ) -> CommandQueue<'a, Alloc> {
        // assume no more than 1/16 of the stream is block_types which may chop up literals
        // also there's the first btypel and a potential wrap around the ring buffer
        let queue = allocate::<StaticCommand, _>(alloc, num_commands * 17 / 16 + 4);
        CommandQueue {
            mc: alloc,
            queue, // always need a spare command in case the ring buffer splits a literal into two
            pred_mode,
            mb,
            mb_byte_offset: 0,
            loc: 0,
            best_strides_per_block_type: best_strides,
            entropy_tally_scratch,
            entropy_pyramid,
            stride_detection_quality,
            high_entropy_detection_quality,
            context_map_entropy,
            block_type_literal: 0,
            best_stride_index: 0,
            overfull: false,
        }
    }
    fn full(&self) -> bool {
        self.loc == self.queue.len()
    }
    fn error_if_full(&mut self) {
        if self.full() {
            self.overfull = true;
        }
    }
    fn clear(&mut self) {
        self.loc = 0;
        self.block_type_literal = 0;
    }
    fn free<Cb>(&mut self, callback: &mut Cb) -> Result<(), ()>
    where
        Cb: FnMut(
            &mut interface::PredictionModeContextMap<InputReferenceMut>,
            &mut [interface::StaticCommand],
            InputPair,
            &mut Alloc,
        ),
    {
        callback(
            &mut self.pred_mode,
            self.queue.slice_mut().split_at_mut(self.loc).0,
            self.mb,
            self.mc,
        );
        self.clear();
        self.entropy_tally_scratch.free(self.mc);
        self.entropy_pyramid.free(self.mc);
        self.context_map_entropy.free(self.mc);
        <Alloc as Allocator<StaticCommand>>::free_cell(self.mc, core::mem::take(&mut self.queue));
        <Alloc as Allocator<u8>>::free_cell(
            self.mc,
            core::mem::take(&mut self.best_strides_per_block_type),
        );
        if self.overfull {
            return Err(());
        }
        Ok(())
    }
}

impl<'a, Alloc: BrotliAlloc> interface::CommandProcessor<'a> for CommandQueue<'a, Alloc> {
    fn push(&mut self, val: interface::Command<InputReference<'a>>) {
        if self.full() {
            let mut tmp = allocate::<StaticCommand, _>(self.mc, self.queue.slice().len() * 2);
            tmp.slice_mut()
                .split_at_mut(self.queue.slice().len())
                .0
                .clone_from_slice(self.queue.slice());
            <Alloc as Allocator<StaticCommand>>::free_cell(
                self.mc,
                core::mem::replace(&mut self.queue, tmp),
            );
        }
        if !self.full() {
            self.queue.slice_mut()[self.loc] = val.freeze();
            self.loc += 1;
        } else {
            self.error_if_full();
        }
    }
    fn push_block_switch_literal(&mut self, block_type: u8) {
        self.push(interface::Command::BlockSwitchLiteral(
            interface::LiteralBlockSwitch::new(block_type, 0),
        ))
    }
}

#[cfg(feature = "std")]
fn warn_on_missing_free() {
    let _err = ::std::io::stderr()
        .write(b"Need to free entropy_tally_scratch before dropping CommandQueue\n");
}
#[cfg(not(feature = "std"))]
fn warn_on_missing_free() {
    // no way to warn in this case
}
impl<'a, Alloc: BrotliAlloc> Drop for CommandQueue<'a, Alloc> {
    fn drop(&mut self) {
        if !self.entropy_tally_scratch.is_free() {
            warn_on_missing_free();
        }
    }
}
#[cfg(not(feature = "billing"))]
fn best_singleton_speed_log(_name: &str, _data: &[SpeedAndMax; 2], _cost: &[floatX; 2]) {}
#[cfg(feature = "billing")]
fn best_singleton_speed_log(name: &str, data: &[SpeedAndMax; 2], cost: &[floatX; 2]) {
    println!(
        "{} hi cost: {} lo cost: {}   speeds {:?} {:?}",
        name, cost[1], cost[0], data[1], data[0]
    );
}

#[cfg(not(feature = "billing"))]
fn best_speed_log(_name: &str, _data: &[SpeedAndMax; 2], _cost: &[floatX; 2]) {}
#[cfg(feature = "billing")]
fn best_speed_log(name: &str, data: &[SpeedAndMax; 2], cost: &[floatX; 2]) {
    for high in 0..2 {
        println!(
            "{} Speed [ inc: {}, max: {}, algo: {} ] cost: {}",
            name,
            if high != 0 { "hi" } else { "lo" },
            data[high].0,
            data[high].1,
            cost[high]
        );
    }
}

fn process_command_queue<'a, CmdProcessor: interface::CommandProcessor<'a>>(
    command_queue: &mut CmdProcessor,
    input: InputPair<'a>,
    commands: &[Command],
    dist_cache: &[i32; kNumDistanceCacheEntries],
    mut recoder_state: RecoderState,
    block_type: &MetaBlockSplitRefs,
    params: &BrotliEncoderParams,
    context_type: Option<ContextType>,
) -> RecoderState {
    let mut input_iter = input;
    let mut local_dist_cache = [0i32; kNumDistanceCacheEntries];
    local_dist_cache.clone_from_slice(&dist_cache[..]);
    let mut btypel_counter = 0usize;
    let mut btypec_counter = 0usize;
    let mut btyped_counter = 0usize;
    let mut btypel_sub = if block_type.btypel.num_types == 1 {
        1u32 << 31
    } else {
        block_type.btypel.lengths[0]
    };
    let mut btypec_sub = if block_type.btypec.num_types == 1 {
        1u32 << 31
    } else {
        block_type.btypec.lengths[0]
    };
    let mut btyped_sub = if block_type.btyped.num_types == 1 {
        1u32 << 31
    } else {
        block_type.btyped.lengths[0]
    };
    {
        command_queue.push_block_switch_literal(0);
    }
    let mut mb_len = input.len();
    for cmd in commands.iter() {
        let (inserts, interim) = input_iter.split_at(min(cmd.insert_len_ as usize, mb_len));
        recoder_state.num_bytes_encoded += inserts.len();
        let _copy_cursor = input.len() - interim.len();
        // let distance_context = cmd.distance_context();
        let copylen_code = cmd.copy_len_code();

        let (prev_dist_index, dist_offset) = cmd.distance_index_and_offset(&params.dist);
        let final_distance: usize;
        if prev_dist_index == 0 {
            final_distance = dist_offset as usize;
        } else {
            final_distance =
                (local_dist_cache[prev_dist_index - 1] as isize + dist_offset) as usize;
        }
        let copy_len = copylen_code as usize;
        let actual_copy_len: usize;
        let max_distance = min(
            recoder_state.num_bytes_encoded,
            window_size_from_lgwin(params.lgwin),
        );
        assert!(inserts.len() <= mb_len);
        if inserts.len() != 0 {
            let mut tmp_inserts = inserts;
            while tmp_inserts.len() > btypel_sub as usize {
                // we have to divide some:
                let (in_a, in_b) = tmp_inserts.split_at(btypel_sub as usize);
                if in_a.len() != 0 {
                    if context_type.is_some() {
                        command_queue.push_literals(&in_a);
                    } else if params.high_entropy_detection_quality == 0 {
                        command_queue.push_literals(&in_a);
                    } else {
                        command_queue.push_rand_literals(&in_a);
                    }
                }
                mb_len -= in_a.len();
                tmp_inserts = in_b;
                btypel_counter += 1;
                if block_type.btypel.types.len() > btypel_counter {
                    btypel_sub = block_type.btypel.lengths[btypel_counter];
                    command_queue
                        .push_block_switch_literal(block_type.btypel.types[btypel_counter]);
                } else {
                    btypel_sub = 1u32 << 31;
                }
            }
            if context_type.is_some() {
                command_queue.push_literals(&tmp_inserts);
            } else if params.high_entropy_detection_quality == 0 {
                command_queue.push_literals(&tmp_inserts);
            } else {
                command_queue.push_rand_literals(&tmp_inserts);
            }
            if tmp_inserts.len() != 0 {
                mb_len -= tmp_inserts.len();
                btypel_sub -= tmp_inserts.len() as u32;
            }
        }
        if final_distance > max_distance {
            // is dictionary
            assert!(copy_len >= 4);
            assert!(copy_len < 25);
            let dictionary_offset = final_distance - max_distance - 1;
            let ndbits = kBrotliDictionarySizeBitsByLength[copy_len] as usize;
            let action = dictionary_offset >> ndbits;
            let word_sub_index = dictionary_offset & ((1 << ndbits) - 1);
            let word_index =
                word_sub_index * copy_len + kBrotliDictionaryOffsetsByLength[copy_len] as usize;
            let raw_word = &kBrotliDictionary[word_index..word_index + copy_len];
            let mut transformed_word = [0u8; 38];
            actual_copy_len = TransformDictionaryWord(
                &mut transformed_word[..],
                raw_word,
                copy_len as i32,
                action as i32,
            ) as usize;
            if actual_copy_len <= mb_len {
                command_queue.push(interface::Command::Dict(interface::DictCommand {
                    word_size: copy_len as u8,
                    transform: action as u8,
                    final_size: actual_copy_len as u8,
                    empty: 0,
                    word_id: word_sub_index as u32,
                }));
                mb_len -= actual_copy_len;
                assert_eq!(
                    InputPair(
                        InputReference {
                            data: transformed_word.split_at(actual_copy_len).0,
                            orig_offset: 0
                        },
                        InputReference::default()
                    ),
                    interim.split_at(actual_copy_len).0
                );
            } else if mb_len != 0 {
                // truncated dictionary word: represent it as literals instead
                // won't be random noise since it fits in the dictionary, so we won't check for rand
                command_queue.push_literals(&interim.split_at(mb_len).0);
                mb_len = 0;
                assert_eq!(
                    InputPair(
                        InputReference {
                            data: transformed_word.split_at(mb_len).0,
                            orig_offset: 0
                        },
                        InputReference::default()
                    ),
                    interim.split_at(mb_len).0
                );
            }
        } else {
            actual_copy_len = min(mb_len, copy_len);
            if actual_copy_len != 0 {
                command_queue.push(interface::Command::Copy(interface::CopyCommand {
                    distance: final_distance as u32,
                    num_bytes: actual_copy_len as u32,
                }));
            }
            mb_len -= actual_copy_len;
            if prev_dist_index != 1 || dist_offset != 0 {
                // update distance cache unless it's the "0 distance symbol"
                let mut tmp_dist_cache = [0i32; kNumDistanceCacheEntries - 1];
                tmp_dist_cache.clone_from_slice(&local_dist_cache[..kNumDistanceCacheEntries - 1]);
                local_dist_cache[1..].clone_from_slice(&tmp_dist_cache[..]);
                local_dist_cache[0] = final_distance as i32;
            }
        }
        {
            btypec_sub -= 1;
            if btypec_sub == 0 {
                btypec_counter += 1;
                if block_type.btypec.types.len() > btypec_counter {
                    btypec_sub = block_type.btypec.lengths[btypec_counter];
                    command_queue.push(interface::Command::BlockSwitchCommand(
                        interface::BlockSwitch(block_type.btypec.types[btypec_counter]),
                    ));
                } else {
                    btypec_sub = 1u32 << 31;
                }
            }
        }
        if copy_len != 0 && cmd.cmd_prefix_ >= 128 {
            btyped_sub -= 1;
            if btyped_sub == 0 {
                btyped_counter += 1;
                if block_type.btyped.types.len() > btyped_counter {
                    btyped_sub = block_type.btyped.lengths[btyped_counter];
                    command_queue.push(interface::Command::BlockSwitchDistance(
                        interface::BlockSwitch(block_type.btyped.types[btyped_counter]),
                    ));
                } else {
                    btyped_sub = 1u32 << 31;
                }
            }
        }

        let (copied, remainder) = interim.split_at(actual_copy_len);
        recoder_state.num_bytes_encoded += copied.len();
        input_iter = remainder;
    }
    recoder_state
}

fn LogMetaBlock<'a, Alloc: BrotliAlloc, Cb>(
    alloc: &mut Alloc,
    commands: &[Command],
    input0: &'a [u8],
    input1: &'a [u8],
    dist_cache: &[i32; kNumDistanceCacheEntries],
    recoder_state: &mut RecoderState,
    block_type: MetaBlockSplitRefs,
    params: &BrotliEncoderParams,
    context_type: Option<ContextType>,
    callback: &mut Cb,
) where
    Cb: FnMut(
        &mut interface::PredictionModeContextMap<InputReferenceMut>,
        &mut [interface::StaticCommand],
        InputPair,
        &mut Alloc,
    ),
{
    let mut local_literal_context_map = [0u8; 256 * 64];
    let mut local_distance_context_map = [0u8; 256 * 64 + interface::DISTANCE_CONTEXT_MAP_OFFSET];
    assert_eq!(
        *block_type.btypel.types.iter().max().unwrap_or(&0) as u32 + 1,
        block_type.btypel.num_types
    );
    assert_eq!(
        *block_type.btypec.types.iter().max().unwrap_or(&0) as u32 + 1,
        block_type.btypec.num_types
    );
    assert_eq!(
        *block_type.btyped.types.iter().max().unwrap_or(&0) as u32 + 1,
        block_type.btyped.num_types
    );
    if block_type.literal_context_map.len() <= 256 * 64 {
        for (index, item) in block_type.literal_context_map.iter().enumerate() {
            local_literal_context_map[index] = *item as u8;
        }
    }
    if block_type.distance_context_map.len() <= 256 * 64 {
        for (index, item) in block_type.distance_context_map.iter().enumerate() {
            local_distance_context_map[interface::DISTANCE_CONTEXT_MAP_OFFSET + index] =
                *item as u8;
        }
    }

    let mut prediction_mode = interface::PredictionModeContextMap::<InputReferenceMut> {
        literal_context_map: InputReferenceMut {
            data: local_literal_context_map
                .split_at_mut(block_type.literal_context_map.len())
                .0,
            orig_offset: 0,
        },
        predmode_speed_and_distance_context_map: InputReferenceMut {
            data: local_distance_context_map
                .split_at_mut(
                    interface::PredictionModeContextMap::<InputReference>::size_of_combined_array(
                        block_type.distance_context_map.len(),
                    ),
                )
                .0,
            orig_offset: 0,
        },
    };
    for item in prediction_mode.get_mixing_values_mut().iter_mut() {
        *item = prior_eval::WhichPrior::STRIDE1 as u8;
    }
    prediction_mode
        .set_stride_context_speed([params.literal_adaptation[2], params.literal_adaptation[3]]);
    prediction_mode
        .set_context_map_speed([params.literal_adaptation[0], params.literal_adaptation[1]]);
    prediction_mode.set_combined_stride_context_speed([
        params.literal_adaptation[0],
        params.literal_adaptation[1],
    ]);

    prediction_mode.set_literal_prediction_mode(interface::LiteralPredictionModeNibble(
        context_type.unwrap_or(ContextType::CONTEXT_LSB6) as u8,
    ));
    let mut entropy_tally_scratch;
    let mut entropy_pyramid;
    if params.stride_detection_quality == 1 || params.stride_detection_quality == 2 {
        entropy_tally_scratch = find_stride::EntropyTally::<Alloc>::new(alloc, None);
        entropy_pyramid = find_stride::EntropyPyramid::<Alloc>::new(alloc);
        entropy_pyramid.populate(input0, input1, &mut entropy_tally_scratch);
    } else {
        entropy_tally_scratch = find_stride::EntropyTally::<Alloc>::disabled_placeholder(alloc);
        entropy_pyramid = find_stride::EntropyPyramid::<Alloc>::disabled_placeholder(alloc);
    }
    let input = InputPair(
        InputReference {
            data: input0,
            orig_offset: 0,
        },
        InputReference {
            data: input1,
            orig_offset: input0.len(),
        },
    );
    let mut best_strides = alloc_default::<u8, Alloc>();
    if params.stride_detection_quality > 2 {
        let mut stride_selector =
            stride_eval::StrideEval::<Alloc>::new(alloc, input, &prediction_mode, params);
        process_command_queue(
            &mut stride_selector,
            input,
            commands,
            dist_cache,
            *recoder_state,
            &block_type,
            params,
            context_type,
        );
        let ntypes = stride_selector.num_types();
        best_strides = allocate::<u8, _>(stride_selector.alloc(), ntypes);
        stride_selector.choose_stride(best_strides.slice_mut());
    }
    let mut context_map_entropy = ContextMapEntropy::<Alloc>::new(
        alloc,
        input,
        entropy_pyramid.stride_last_level_range(),
        prediction_mode,
        params.cdf_adaptation_detection,
    );
    if params.cdf_adaptation_detection != 0 {
        process_command_queue(
            &mut context_map_entropy,
            input,
            commands,
            dist_cache,
            *recoder_state,
            &block_type,
            params,
            context_type,
        );
        {
            let (cm_speed, cm_cost) = context_map_entropy.best_singleton_speeds(true, false);
            let (stride_speed, stride_cost) =
                context_map_entropy.best_singleton_speeds(false, false);
            let (combined_speed, combined_cost) =
                context_map_entropy.best_singleton_speeds(false, true);
            best_singleton_speed_log("CM", &cm_speed, &cm_cost);
            best_singleton_speed_log("stride", &stride_speed, &stride_cost);
            best_singleton_speed_log("combined", &combined_speed, &combined_cost);
        }

        let cm_speed = context_map_entropy.best_speeds(true, false);
        let stride_speed = context_map_entropy.best_speeds(false, false);
        let combined_speed = context_map_entropy.best_speeds(false, true);
        let acost = context_map_entropy.best_speeds_costs(true, false);
        let bcost = context_map_entropy.best_speeds_costs(false, false);
        let ccost = context_map_entropy.best_speeds_costs(false, true);
        context_map_entropy
            .prediction_mode_mut()
            .set_stride_context_speed(speed_to_tuple(stride_speed));
        context_map_entropy
            .prediction_mode_mut()
            .set_context_map_speed(speed_to_tuple(cm_speed));
        context_map_entropy
            .prediction_mode_mut()
            .set_combined_stride_context_speed(speed_to_tuple(combined_speed));

        best_speed_log("CM", &cm_speed, &acost);
        best_speed_log("Stride", &stride_speed, &bcost);
        best_speed_log("StrideCombined", &combined_speed, &ccost);
    }
    let mut prior_selector = prior_eval::PriorEval::<Alloc>::new(
        alloc,
        input,
        entropy_pyramid.stride_last_level_range(),
        context_map_entropy.take_prediction_mode(),
        params,
    );
    if params.prior_bitmask_detection != 0 {
        process_command_queue(
            &mut prior_selector,
            input,
            commands,
            dist_cache,
            *recoder_state,
            &block_type,
            params,
            context_type,
        );
        prior_selector.choose_bitmask();
    }
    let prediction_mode = prior_selector.take_prediction_mode();
    prior_selector.free(alloc);
    let mut command_queue = CommandQueue::new(
        alloc,
        commands.len(),
        prediction_mode,
        input,
        params.stride_detection_quality,
        params.high_entropy_detection_quality,
        context_map_entropy,
        best_strides,
        entropy_tally_scratch,
        entropy_pyramid,
    );

    *recoder_state = process_command_queue(
        &mut command_queue,
        input,
        commands,
        dist_cache,
        *recoder_state,
        &block_type,
        params,
        context_type,
    );
    command_queue.free(callback).unwrap();
    //   ::std::io::stderr().write(input0).unwrap();
    //   ::std::io::stderr().write(input1).unwrap();
}

static kBlockLengthPrefixCode: [PrefixCodeRange; BROTLI_NUM_BLOCK_LEN_SYMBOLS] = [
    PrefixCodeRange {
        offset: 1u32,
        nbits: 2u32,
    },
    PrefixCodeRange {
        offset: 5u32,
        nbits: 2u32,
    },
    PrefixCodeRange {
        offset: 9u32,
        nbits: 2u32,
    },
    PrefixCodeRange {
        offset: 13u32,
        nbits: 2u32,
    },
    PrefixCodeRange {
        offset: 17u32,
        nbits: 3u32,
    },
    PrefixCodeRange {
        offset: 25u32,
        nbits: 3u32,
    },
    PrefixCodeRange {
        offset: 33u32,
        nbits: 3u32,
    },
    PrefixCodeRange {
        offset: 41u32,
        nbits: 3u32,
    },
    PrefixCodeRange {
        offset: 49u32,
        nbits: 4u32,
    },
    PrefixCodeRange {
        offset: 65u32,
        nbits: 4u32,
    },
    PrefixCodeRange {
        offset: 81u32,
        nbits: 4u32,
    },
    PrefixCodeRange {
        offset: 97u32,
        nbits: 4u32,
    },
    PrefixCodeRange {
        offset: 113u32,
        nbits: 5u32,
    },
    PrefixCodeRange {
        offset: 145u32,
        nbits: 5u32,
    },
    PrefixCodeRange {
        offset: 177u32,
        nbits: 5u32,
    },
    PrefixCodeRange {
        offset: 209u32,
        nbits: 5u32,
    },
    PrefixCodeRange {
        offset: 241u32,
        nbits: 6u32,
    },
    PrefixCodeRange {
        offset: 305u32,
        nbits: 6u32,
    },
    PrefixCodeRange {
        offset: 369u32,
        nbits: 7u32,
    },
    PrefixCodeRange {
        offset: 497u32,
        nbits: 8u32,
    },
    PrefixCodeRange {
        offset: 753u32,
        nbits: 9u32,
    },
    PrefixCodeRange {
        offset: 1265u32,
        nbits: 10u32,
    },
    PrefixCodeRange {
        offset: 2289u32,
        nbits: 11u32,
    },
    PrefixCodeRange {
        offset: 4337u32,
        nbits: 12u32,
    },
    PrefixCodeRange {
        offset: 8433u32,
        nbits: 13u32,
    },
    PrefixCodeRange {
        offset: 16625u32,
        nbits: 24u32,
    },
];

fn BrotliWriteBits(n_bits: u8, bits: u64, pos: &mut usize, array: &mut [u8]) {
    assert_eq!(bits >> n_bits, 0);
    assert!(n_bits <= 56);
    let ptr_offset: usize = ((*pos >> 3) as u32) as usize;
    let mut v = array[ptr_offset] as u64;
    v |= bits << ((*pos) as u64 & 7);
    array[ptr_offset + 7] = (v >> 56) as u8;
    array[ptr_offset + 6] = ((v >> 48) & 0xff) as u8;
    array[ptr_offset + 5] = ((v >> 40) & 0xff) as u8;
    array[ptr_offset + 4] = ((v >> 32) & 0xff) as u8;
    array[ptr_offset + 3] = ((v >> 24) & 0xff) as u8;
    array[ptr_offset + 2] = ((v >> 16) & 0xff) as u8;
    array[ptr_offset + 1] = ((v >> 8) & 0xff) as u8;
    array[ptr_offset] = (v & 0xff) as u8;
    *pos += n_bits as usize
}

fn BrotliWriteBitsPrepareStorage(pos: usize, array: &mut [u8]) {
    assert_eq!(pos & 7, 0);
    array[pos >> 3] = 0;
}

fn BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(
    num_codes: i32,
    code_length_bitdepth: &[u8],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    static kStorageOrder: [u8; 18] = [1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15];
    static kHuffmanBitLengthHuffmanCodeSymbols: [u8; 6] = [0, 7, 3, 2, 1, 15];
    static kHuffmanBitLengthHuffmanCodeBitLengths: [u8; 6] = [2, 4, 3, 2, 2, 4];
    let mut skip_some: u64 = 0u64;
    let mut codes_to_store: u64 = 18;
    if num_codes > 1i32 {
        'break5: while codes_to_store > 0 {
            {
                if code_length_bitdepth
                    [(kStorageOrder[codes_to_store.wrapping_sub(1) as usize] as usize)]
                    as i32
                    != 0i32
                {
                    break 'break5;
                }
            }
            codes_to_store = codes_to_store.wrapping_sub(1);
        }
    }
    if code_length_bitdepth[(kStorageOrder[0] as usize)] as i32 == 0i32
        && (code_length_bitdepth[(kStorageOrder[1] as usize)] as i32 == 0i32)
    {
        skip_some = 2;
        if code_length_bitdepth[(kStorageOrder[2] as usize)] as i32 == 0i32 {
            skip_some = 3;
        }
    }
    BrotliWriteBits(2, skip_some, storage_ix, storage);

    for i in skip_some..codes_to_store {
        let l = code_length_bitdepth[kStorageOrder[i as usize] as usize] as usize;
        BrotliWriteBits(
            kHuffmanBitLengthHuffmanCodeBitLengths[l],
            kHuffmanBitLengthHuffmanCodeSymbols[l] as u64,
            storage_ix,
            storage,
        );
    }
}

fn BrotliStoreHuffmanTreeToBitMask(
    huffman_tree_size: usize,
    huffman_tree: &[u8],
    huffman_tree_extra_bits: &[u8],
    code_length_bitdepth: &[u8],
    code_length_bitdepth_symbols: &[u16],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    for i in 0usize..huffman_tree_size {
        let ix: usize = huffman_tree[i] as usize;
        BrotliWriteBits(
            code_length_bitdepth[ix],
            code_length_bitdepth_symbols[ix] as (u64),
            storage_ix,
            storage,
        );
        if ix == 16usize {
            BrotliWriteBits(2, huffman_tree_extra_bits[i] as (u64), storage_ix, storage);
        } else if ix == 17usize {
            BrotliWriteBits(3, huffman_tree_extra_bits[i] as (u64), storage_ix, storage);
        }
    }
}

pub fn BrotliStoreHuffmanTree(
    depths: &[u8],
    num: usize,
    tree: &mut [HuffmanTree],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut huffman_tree = [0u8; 704];
    let mut huffman_tree_extra_bits = [0u8; 704];
    let mut huffman_tree_size = 0usize;
    let mut code_length_bitdepth = [0u8; 18];
    let mut code_length_bitdepth_symbols = [0u16; 18];
    let mut huffman_tree_histogram = [0u32; 18];
    let mut i: usize;
    let mut num_codes: i32 = 0i32;
    let mut code: usize = 0usize;

    BrotliWriteHuffmanTree(
        depths,
        num,
        &mut huffman_tree_size,
        &mut huffman_tree[..],
        &mut huffman_tree_extra_bits[..],
    );
    for i in 0usize..huffman_tree_size {
        let _rhs = 1;
        let _lhs = &mut huffman_tree_histogram[huffman_tree[i] as usize];
        *_lhs = (*_lhs).wrapping_add(_rhs as u32);
    }
    i = 0usize;
    'break3: while i < 18usize {
        {
            if huffman_tree_histogram[i] != 0 {
                if num_codes == 0i32 {
                    code = i;
                    num_codes = 1i32;
                } else if num_codes == 1i32 {
                    num_codes = 2i32;
                    {
                        break 'break3;
                    }
                }
            }
        }
        i = i.wrapping_add(1);
    }
    BrotliCreateHuffmanTree(
        &mut huffman_tree_histogram,
        18usize,
        5i32,
        tree,
        &mut code_length_bitdepth,
    );
    BrotliConvertBitDepthsToSymbols(
        &mut code_length_bitdepth,
        18usize,
        &mut code_length_bitdepth_symbols,
    );
    BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(
        num_codes,
        &code_length_bitdepth,
        storage_ix,
        storage,
    );
    if num_codes == 1i32 {
        code_length_bitdepth[code] = 0u8;
    }
    BrotliStoreHuffmanTreeToBitMask(
        huffman_tree_size,
        &huffman_tree,
        &huffman_tree_extra_bits,
        &code_length_bitdepth,
        &code_length_bitdepth_symbols,
        storage_ix,
        storage,
    );
}

fn StoreStaticCodeLengthCode(storage_ix: &mut usize, storage: &mut [u8]) {
    BrotliWriteBits(40, 0xff_5555_5554, storage_ix, storage);
}

pub struct SimpleSortHuffmanTree {}

impl HuffmanComparator for SimpleSortHuffmanTree {
    fn Cmp(&self, v0: &HuffmanTree, v1: &HuffmanTree) -> bool {
        v0.total_count_ < v1.total_count_
    }
}

pub fn BrotliBuildAndStoreHuffmanTreeFast<AllocHT: alloc::Allocator<HuffmanTree>>(
    m: &mut AllocHT,
    histogram: &[u32],
    histogram_total: usize,
    max_bits: usize,
    depth: &mut [u8],
    bits: &mut [u16],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut count: u64 = 0;
    let mut symbols: [u64; 4] = [0; 4];
    let mut length: u64 = 0;
    let mut total: usize = histogram_total;
    while total != 0usize {
        if histogram[(length as usize)] != 0 {
            if count < 4 {
                symbols[count as usize] = length;
            }
            count = count.wrapping_add(1);
            total = total.wrapping_sub(histogram[(length as usize)] as usize);
        }
        length = length.wrapping_add(1);
    }
    if count <= 1 {
        BrotliWriteBits(4, 1, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[0], storage_ix, storage);
        depth[symbols[0] as usize] = 0u8;
        bits[symbols[0] as usize] = 0u16;
        return;
    }
    for depth_elem in depth[..(length as usize)].iter_mut() {
        *depth_elem = 0; // memset
    }
    {
        // FIXME: computation in u64, followed by allocation which might be less than u64
        let max_tree_size: u64 = (2u64).wrapping_mul(length).wrapping_add(1);
        // FIXME: makes little sense to test if N+1 > 0 -- always true unless wrapping. Perhaps use allocate() instead?
        let mut tree = alloc_or_default::<HuffmanTree, _>(m, max_tree_size as usize);
        let mut count_limit: u32;
        count_limit = 1u32;
        'break11: loop {
            {
                let mut node_index: u32 = 0u32;
                let mut l: u64;
                l = length;
                while l != 0 {
                    l = l.wrapping_sub(1);
                    if histogram[l as usize] != 0 {
                        if histogram[l as usize] >= count_limit {
                            tree.slice_mut()[node_index as usize] =
                                HuffmanTree::new(histogram[l as usize], -1, l as i16);
                        } else {
                            tree.slice_mut()[node_index as usize] =
                                HuffmanTree::new(count_limit, -1, l as i16);
                        }
                        node_index = node_index.wrapping_add(1);
                    }
                }
                {
                    let n: i32 = node_index as i32;

                    let mut i: i32 = 0i32;
                    let mut j: i32 = n + 1i32;
                    let mut k: i32;
                    SortHuffmanTreeItems(tree.slice_mut(), n as usize, SimpleSortHuffmanTree {});
                    let sentinel = HuffmanTree::new(u32::MAX, -1, -1);
                    tree.slice_mut()[(node_index.wrapping_add(1) as usize)] = sentinel;
                    tree.slice_mut()[(node_index as usize)] = sentinel;
                    node_index = node_index.wrapping_add(2);
                    k = n - 1i32;
                    while k > 0i32 {
                        {
                            let left: i32;
                            let right: i32;
                            if (tree.slice()[(i as usize)]).total_count_
                                <= (tree.slice()[(j as usize)]).total_count_
                            {
                                left = i;
                                i += 1;
                            } else {
                                left = j;
                                j += 1;
                            }
                            if (tree.slice()[(i as usize)]).total_count_
                                <= (tree.slice()[(j as usize)]).total_count_
                            {
                                right = i;
                                i += 1;
                            } else {
                                right = j;
                                j += 1;
                            }
                            let sum_total = (tree.slice()[(left as usize)])
                                .total_count_
                                .wrapping_add((tree.slice()[(right as usize)]).total_count_);
                            let tree_ind = (node_index.wrapping_sub(1) as usize);
                            (tree.slice_mut()[tree_ind]).total_count_ = sum_total;
                            (tree.slice_mut()[tree_ind]).index_left_ = left as i16;
                            (tree.slice_mut()[tree_ind]).index_right_or_value_ = right as i16;
                            tree.slice_mut()[(node_index as usize)] = sentinel;
                            node_index = node_index.wrapping_add(1);
                        }
                        k -= 1;
                    }
                    if BrotliSetDepth(2i32 * n - 1i32, tree.slice_mut(), depth, 14i32) {
                        break 'break11;
                    }
                }
            }
            count_limit = count_limit.wrapping_mul(2);
        }
        {
            m.free_cell(core::mem::take(&mut tree));
        }
    }
    BrotliConvertBitDepthsToSymbols(depth, length as usize, bits);
    if count <= 4 {
        BrotliWriteBits(2, 1, storage_ix, storage);
        BrotliWriteBits(2, count.wrapping_sub(1), storage_ix, storage);
        for i in 0..count as usize {
            for j in i + 1..count as usize {
                if depth[symbols[j] as usize] < depth[symbols[i] as usize] {
                    symbols.swap(j, i);
                }
            }
        }
        if count == 2 {
            BrotliWriteBits(max_bits as u8, symbols[0], storage_ix, storage);
            BrotliWriteBits(max_bits as u8, symbols[1], storage_ix, storage);
        } else if count == 3 {
            BrotliWriteBits(max_bits as u8, symbols[0], storage_ix, storage);
            BrotliWriteBits(max_bits as u8, symbols[1], storage_ix, storage);
            BrotliWriteBits(max_bits as u8, symbols[2], storage_ix, storage);
        } else {
            BrotliWriteBits(max_bits as u8, symbols[0], storage_ix, storage);
            BrotliWriteBits(max_bits as u8, symbols[1], storage_ix, storage);
            BrotliWriteBits(max_bits as u8, symbols[2], storage_ix, storage);
            BrotliWriteBits(max_bits as u8, symbols[3], storage_ix, storage);
            BrotliWriteBits(
                1,
                if depth[(symbols[0] as usize)] as i32 == 1i32 {
                    1i32
                } else {
                    0i32
                } as (u64),
                storage_ix,
                storage,
            );
        }
    } else {
        let mut previous_value: u8 = 8u8;
        let mut i: u64;
        StoreStaticCodeLengthCode(storage_ix, storage);
        i = 0;
        while i < length {
            let value: u8 = depth[(i as usize)];
            let mut reps: u64 = 1;
            let mut k: u64;
            k = i.wrapping_add(1);
            while k < length && (depth[(k as usize)] as i32 == value as i32) {
                {
                    reps = reps.wrapping_add(1);
                }
                k = k.wrapping_add(1);
            }
            i = i.wrapping_add(reps);
            if value as i32 == 0i32 {
                BrotliWriteBits(
                    kZeroRepsDepth[reps as usize] as u8,
                    kZeroRepsBits[reps as usize] as u64,
                    storage_ix,
                    storage,
                );
            } else {
                if previous_value as i32 != value as i32 {
                    BrotliWriteBits(
                        kCodeLengthDepth[value as usize],
                        kCodeLengthBits[value as usize] as (u64),
                        storage_ix,
                        storage,
                    );
                    reps = reps.wrapping_sub(1);
                }
                if reps < 3 {
                    while reps != 0 {
                        reps = reps.wrapping_sub(1);
                        BrotliWriteBits(
                            kCodeLengthDepth[value as usize],
                            kCodeLengthBits[value as usize] as (u64),
                            storage_ix,
                            storage,
                        );
                    }
                } else {
                    reps = reps.wrapping_sub(3);
                    BrotliWriteBits(
                        kNonZeroRepsDepth[reps as usize] as u8,
                        kNonZeroRepsBits[reps as usize] as u64,
                        storage_ix,
                        storage,
                    );
                }
                previous_value = value;
            }
        }
    }
}

pub struct MetaBlockSplit<
    Alloc: alloc::Allocator<u8>
        + alloc::Allocator<u32>
        + alloc::Allocator<HistogramLiteral>
        + alloc::Allocator<HistogramCommand>
        + alloc::Allocator<HistogramDistance>,
> {
    pub literal_split: BlockSplit<Alloc>,
    pub command_split: BlockSplit<Alloc>,
    pub distance_split: BlockSplit<Alloc>,
    pub literal_context_map: <Alloc as Allocator<u32>>::AllocatedMemory,
    pub literal_context_map_size: usize,
    pub distance_context_map: <Alloc as Allocator<u32>>::AllocatedMemory,
    pub distance_context_map_size: usize,
    pub literal_histograms: <Alloc as Allocator<HistogramLiteral>>::AllocatedMemory,
    pub literal_histograms_size: usize,
    pub command_histograms: <Alloc as Allocator<HistogramCommand>>::AllocatedMemory,
    pub command_histograms_size: usize,
    pub distance_histograms: <Alloc as Allocator<HistogramDistance>>::AllocatedMemory,
    pub distance_histograms_size: usize,
}
impl<
        Alloc: alloc::Allocator<u8>
            + alloc::Allocator<u32>
            + alloc::Allocator<HistogramLiteral>
            + alloc::Allocator<HistogramCommand>
            + alloc::Allocator<HistogramDistance>,
    > Default for MetaBlockSplit<Alloc>
{
    fn default() -> Self {
        Self {
            literal_split: BlockSplit::default(),
            command_split: BlockSplit::default(),
            distance_split: BlockSplit::default(),
            literal_context_map: alloc_default::<u32, Alloc>(),
            literal_context_map_size: 0,
            distance_context_map: alloc_default::<u32, Alloc>(),
            distance_context_map_size: 0,
            literal_histograms: alloc_default::<HistogramLiteral, Alloc>(),
            literal_histograms_size: 0,
            command_histograms: alloc_default::<HistogramCommand, Alloc>(),
            command_histograms_size: 0,
            distance_histograms: alloc_default::<HistogramDistance, Alloc>(),
            distance_histograms_size: 0,
        }
    }
}

impl<
        Alloc: alloc::Allocator<u8>
            + alloc::Allocator<u32>
            + alloc::Allocator<HistogramLiteral>
            + alloc::Allocator<HistogramCommand>
            + alloc::Allocator<HistogramDistance>,
    > MetaBlockSplit<Alloc>
{
    pub fn new() -> Self {
        Self::default()
    }

    pub fn destroy(&mut self, alloc: &mut Alloc) {
        self.literal_split.destroy(alloc);
        self.command_split.destroy(alloc);
        self.distance_split.destroy(alloc);
        <Alloc as Allocator<u32>>::free_cell(alloc, core::mem::take(&mut self.literal_context_map));
        self.literal_context_map_size = 0;
        <Alloc as Allocator<u32>>::free_cell(
            alloc,
            core::mem::take(&mut self.distance_context_map),
        );
        self.distance_context_map_size = 0;
        <Alloc as Allocator<HistogramLiteral>>::free_cell(
            alloc,
            core::mem::take(&mut self.literal_histograms),
        );

        self.literal_histograms_size = 0;
        <Alloc as Allocator<HistogramCommand>>::free_cell(
            alloc,
            core::mem::take(&mut self.command_histograms),
        );
        self.command_histograms_size = 0;
        <Alloc as Allocator<HistogramDistance>>::free_cell(
            alloc,
            core::mem::take(&mut self.distance_histograms),
        );
        self.distance_histograms_size = 0;
    }
}
#[derive(Clone, Copy)]
pub struct BlockTypeCodeCalculator {
    pub last_type: usize,
    pub second_last_type: usize,
}

pub struct BlockSplitCode {
    pub type_code_calculator: BlockTypeCodeCalculator,
    pub type_depths: [u8; 258],
    pub type_bits: [u16; 258],
    pub length_depths: [u8; 26],
    pub length_bits: [u16; 26],
}

pub struct BlockEncoder<'a, Alloc: alloc::Allocator<u8> + alloc::Allocator<u16>> {
    /*    pub alloc_u8 : AllocU8,
    pub alloc_u16 : AllocU16,
    pub alloc_u32 : AllocU32,
    pub alloc_ht : AllocHT,*/
    pub histogram_length_: usize,
    pub num_block_types_: usize,
    pub block_types_: &'a [u8],
    pub block_lengths_: &'a [u32],
    pub num_blocks_: usize,
    pub block_split_code_: BlockSplitCode,
    pub block_ix_: usize,
    pub block_len_: usize,
    pub entropy_ix_: usize,
    pub depths_: <Alloc as Allocator<u8>>::AllocatedMemory,
    pub bits_: <Alloc as Allocator<u16>>::AllocatedMemory,
}

fn Log2FloorNonZero(mut n: u64) -> u32 {
    let mut result: u32 = 0u32;
    'loop1: loop {
        if {
            n >>= 1i32;
            n
        } != 0
        {
            result = result.wrapping_add(1);
            continue 'loop1;
        } else {
            break 'loop1;
        }
    }
    result
}

fn BrotliEncodeMlen(length: u32, bits: &mut u64, numbits: &mut u32, nibblesbits: &mut u32) {
    let lg: u32 = (if length == 1u32 {
        1u32
    } else {
        Log2FloorNonZero(length.wrapping_sub(1) as (u64)).wrapping_add(1)
    });
    let mnibbles: u32 = (if lg < 16u32 {
        16u32
    } else {
        lg.wrapping_add(3)
    })
    .wrapping_div(4);
    assert!(length > 0);
    assert!(length <= (1 << 24));
    assert!(lg <= 24);
    *nibblesbits = mnibbles.wrapping_sub(4);
    *numbits = mnibbles.wrapping_mul(4);
    *bits = length.wrapping_sub(1) as u64;
}

fn StoreCompressedMetaBlockHeader(
    is_final_block: bool,
    length: usize,
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut lenbits: u64 = 0;
    let mut nlenbits: u32 = 0;
    let mut nibblesbits: u32 = 0;
    BrotliWriteBits(1, is_final_block.into(), storage_ix, storage);
    if is_final_block {
        BrotliWriteBits(1, 0, storage_ix, storage);
    }
    BrotliEncodeMlen(length as u32, &mut lenbits, &mut nlenbits, &mut nibblesbits);
    BrotliWriteBits(2, nibblesbits as u64, storage_ix, storage);
    BrotliWriteBits(nlenbits as u8, lenbits, storage_ix, storage);
    if !is_final_block {
        BrotliWriteBits(1, 0, storage_ix, storage);
    }
}

impl BlockTypeCodeCalculator {
    fn new() -> Self {
        Self {
            last_type: 1,
            second_last_type: 0,
        }
    }
}

impl<'a, Alloc: Allocator<u8> + Allocator<u16>> BlockEncoder<'a, Alloc> {
    fn new(
        histogram_length: usize,
        num_block_types: usize,
        block_types: &'a [u8],
        block_lengths: &'a [u32],
        num_blocks: usize,
    ) -> Self {
        let block_len = if num_blocks != 0 && !block_lengths.is_empty() {
            block_lengths[0] as usize
        } else {
            0
        };
        Self {
            histogram_length_: histogram_length,
            num_block_types_: num_block_types,
            block_types_: block_types,
            block_lengths_: block_lengths,
            num_blocks_: num_blocks,
            block_split_code_: BlockSplitCode {
                type_code_calculator: BlockTypeCodeCalculator::new(),
                type_depths: [0; 258],
                type_bits: [0; 258],
                length_depths: [0; 26],
                length_bits: [0; 26],
            },
            block_ix_: 0,
            block_len_: block_len,
            entropy_ix_: 0,
            depths_: alloc_default::<u8, Alloc>(),
            bits_: alloc_default::<u16, Alloc>(),
        }
    }
}

fn NextBlockTypeCode(calculator: &mut BlockTypeCodeCalculator, type_: u8) -> usize {
    let type_code: usize = (if type_ as usize == calculator.last_type.wrapping_add(1) {
        1u32
    } else if type_ as usize == calculator.second_last_type {
        0u32
    } else {
        (type_ as u32).wrapping_add(2)
    }) as usize;
    calculator.second_last_type = calculator.last_type;
    calculator.last_type = type_ as usize;
    type_code
}

fn BlockLengthPrefixCode(len: u32) -> u32 {
    let mut code: u32 = (if len >= 177u32 {
        if len >= 753u32 {
            20i32
        } else {
            14i32
        }
    } else if len >= 41u32 {
        7i32
    } else {
        0i32
    }) as u32;
    while code < (26i32 - 1i32) as u32
        && (len >= kBlockLengthPrefixCode[code.wrapping_add(1) as usize].offset)
    {
        code = code.wrapping_add(1);
    }
    code
}

fn StoreVarLenUint8(n: u64, storage_ix: &mut usize, storage: &mut [u8]) {
    if n == 0 {
        BrotliWriteBits(1, 0, storage_ix, storage);
    } else {
        let nbits: u8 = Log2FloorNonZero(n) as u8;
        BrotliWriteBits(1, 1, storage_ix, storage);
        BrotliWriteBits(3, nbits as u64, storage_ix, storage);
        BrotliWriteBits(nbits, n.wrapping_sub(1u64 << nbits), storage_ix, storage);
    }
}

fn StoreSimpleHuffmanTree(
    depths: &[u8],
    symbols: &mut [usize],
    num_symbols: usize,
    max_bits: usize,
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    BrotliWriteBits(2, 1, storage_ix, storage);
    BrotliWriteBits(2, num_symbols.wrapping_sub(1) as u64, storage_ix, storage);
    {
        for i in 0..num_symbols {
            for j in i + 1..num_symbols {
                if depths[symbols[j]] < depths[symbols[i]] {
                    symbols.swap(j, i);
                }
            }
        }
    }
    if num_symbols == 2usize {
        BrotliWriteBits(max_bits as u8, symbols[0] as u64, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[1] as u64, storage_ix, storage);
    } else if num_symbols == 3usize {
        BrotliWriteBits(max_bits as u8, symbols[0] as u64, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[1] as u64, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[2] as u64, storage_ix, storage);
    } else {
        BrotliWriteBits(max_bits as u8, symbols[0] as u64, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[1] as u64, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[2] as u64, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, symbols[3] as u64, storage_ix, storage);
        BrotliWriteBits(
            1,
            if depths[symbols[0]] as i32 == 1i32 {
                1i32
            } else {
                0i32
            } as (u64),
            storage_ix,
            storage,
        );
    }
}

fn BuildAndStoreHuffmanTree(
    histogram: &[u32],
    histogram_length: usize,
    alphabet_size: usize,
    tree: &mut [HuffmanTree],
    depth: &mut [u8],
    bits: &mut [u16],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut count: usize = 0usize;
    let mut s4 = [0usize; 4];
    let mut i: usize;
    let mut max_bits: usize = 0usize;
    i = 0usize;
    'break31: while i < histogram_length {
        {
            if histogram[i] != 0 {
                if count < 4usize {
                    s4[count] = i;
                } else if count > 4usize {
                    break 'break31;
                }
                count = count.wrapping_add(1);
            }
        }
        i = i.wrapping_add(1);
    }
    {
        let mut max_bits_counter: usize = alphabet_size.wrapping_sub(1);
        while max_bits_counter != 0 {
            max_bits_counter >>= 1i32;
            max_bits = max_bits.wrapping_add(1);
        }
    }
    if count <= 1 {
        BrotliWriteBits(4, 1, storage_ix, storage);
        BrotliWriteBits(max_bits as u8, s4[0] as u64, storage_ix, storage);
        depth[s4[0]] = 0u8;
        bits[s4[0]] = 0u16;
        return;
    }

    for depth_elem in depth[..histogram_length].iter_mut() {
        *depth_elem = 0; // memset
    }
    BrotliCreateHuffmanTree(histogram, histogram_length, 15i32, tree, depth);
    BrotliConvertBitDepthsToSymbols(depth, histogram_length, bits);
    if count <= 4usize {
        StoreSimpleHuffmanTree(depth, &mut s4[..], count, max_bits, storage_ix, storage);
    } else {
        BrotliStoreHuffmanTree(depth, histogram_length, tree, storage_ix, storage);
    }
}

fn GetBlockLengthPrefixCode(len: u32, code: &mut usize, n_extra: &mut u32, extra: &mut u32) {
    *code = BlockLengthPrefixCode(len) as usize;
    *n_extra = kBlockLengthPrefixCode[*code].nbits;
    *extra = len.wrapping_sub(kBlockLengthPrefixCode[*code].offset);
}

fn StoreBlockSwitch(
    code: &mut BlockSplitCode,
    block_len: u32,
    block_type: u8,
    is_first_block: bool,
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let typecode: usize = NextBlockTypeCode(&mut code.type_code_calculator, block_type);
    let mut lencode: usize = 0;
    let mut len_nextra: u32 = 0;
    let mut len_extra: u32 = 0;
    if !is_first_block {
        BrotliWriteBits(
            code.type_depths[typecode] as u8,
            code.type_bits[typecode] as (u64),
            storage_ix,
            storage,
        );
    }
    GetBlockLengthPrefixCode(block_len, &mut lencode, &mut len_nextra, &mut len_extra);
    BrotliWriteBits(
        code.length_depths[lencode],
        code.length_bits[lencode] as (u64),
        storage_ix,
        storage,
    );
    BrotliWriteBits(len_nextra as u8, len_extra as (u64), storage_ix, storage);
}

fn BuildAndStoreBlockSplitCode(
    types: &[u8],
    lengths: &[u32],
    num_blocks: usize,
    num_types: usize,
    tree: &mut [HuffmanTree],
    code: &mut BlockSplitCode,
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut type_histo: [u32; 258] = [0; 258];
    let mut length_histo: [u32; 26] = [0; 26];
    let mut i: usize;
    let mut type_code_calculator = BlockTypeCodeCalculator::new();
    i = 0usize;
    while i < num_blocks {
        {
            let type_code: usize = NextBlockTypeCode(&mut type_code_calculator, types[i]);
            if i != 0usize {
                let _rhs = 1;
                let _lhs = &mut type_histo[type_code];
                *_lhs = (*_lhs).wrapping_add(_rhs as u32);
            }
            {
                let _rhs = 1;
                let _lhs = &mut length_histo[BlockLengthPrefixCode(lengths[i]) as usize];
                *_lhs = (*_lhs).wrapping_add(_rhs as u32);
            }
        }
        i = i.wrapping_add(1);
    }
    StoreVarLenUint8(num_types.wrapping_sub(1) as u64, storage_ix, storage);
    if num_types > 1 {
        BuildAndStoreHuffmanTree(
            &mut type_histo[0..],
            num_types.wrapping_add(2),
            num_types.wrapping_add(2),
            tree,
            &mut code.type_depths[0..],
            &mut code.type_bits[0..],
            storage_ix,
            storage,
        );
        BuildAndStoreHuffmanTree(
            &mut length_histo[0..],
            super::constants::BROTLI_NUM_BLOCK_LEN_SYMBOLS, // 26
            super::constants::BROTLI_NUM_BLOCK_LEN_SYMBOLS,
            tree,
            &mut code.length_depths[0..],
            &mut code.length_bits[0..],
            storage_ix,
            storage,
        );
        StoreBlockSwitch(code, lengths[0], types[0], true, storage_ix, storage);
    }
}

impl<Alloc: Allocator<u8> + Allocator<u16>> BlockEncoder<'_, Alloc> {
    fn build_and_store_block_switch_entropy_codes(
        &mut self,
        tree: &mut [HuffmanTree],
        storage_ix: &mut usize,
        storage: &mut [u8],
    ) {
        BuildAndStoreBlockSplitCode(
            self.block_types_,
            self.block_lengths_,
            self.num_blocks_,
            self.num_block_types_,
            tree,
            &mut self.block_split_code_,
            storage_ix,
            storage,
        );
    }
}

fn StoreTrivialContextMap(
    num_types: usize,
    context_bits: usize,
    tree: &mut [HuffmanTree],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    StoreVarLenUint8(num_types.wrapping_sub(1) as u64, storage_ix, storage);
    if num_types > 1 {
        let repeat_code: usize = context_bits.wrapping_sub(1u32 as usize);
        let repeat_bits: usize = (1u32 << repeat_code).wrapping_sub(1) as usize;
        let alphabet_size: usize = num_types.wrapping_add(repeat_code);
        let mut histogram: [u32; 272] = [0; 272];
        let mut depths: [u8; 272] = [0; 272];
        let mut bits: [u16; 272] = [0; 272];
        BrotliWriteBits(1u8, 1u64, storage_ix, storage);
        BrotliWriteBits(4u8, repeat_code.wrapping_sub(1) as u64, storage_ix, storage);
        histogram[repeat_code] = num_types as u32;
        histogram[0] = 1;
        for i in context_bits..alphabet_size {
            histogram[i] = 1;
        }
        BuildAndStoreHuffmanTree(
            &mut histogram[..],
            alphabet_size,
            alphabet_size,
            tree,
            &mut depths[..],
            &mut bits[..],
            storage_ix,
            storage,
        );
        for i in 0usize..num_types {
            let code: usize = if i == 0usize {
                0usize
            } else {
                i.wrapping_add(context_bits).wrapping_sub(1)
            };
            BrotliWriteBits(depths[code], bits[code] as (u64), storage_ix, storage);
            BrotliWriteBits(
                depths[repeat_code],
                bits[repeat_code] as (u64),
                storage_ix,
                storage,
            );
            BrotliWriteBits(repeat_code as u8, repeat_bits as u64, storage_ix, storage);
        }
        BrotliWriteBits(1, 1, storage_ix, storage);
    }
}

fn IndexOf(v: &[u8], v_size: usize, value: u8) -> usize {
    let mut i: usize = 0usize;
    while i < v_size {
        {
            if v[i] as i32 == value as i32 {
                return i;
            }
        }
        i = i.wrapping_add(1);
    }
    i
}

fn MoveToFront(v: &mut [u8], index: usize) {
    let value: u8 = v[index];
    let mut i: usize;
    i = index;
    while i != 0usize {
        {
            v[i] = v[i.wrapping_sub(1)];
        }
        i = i.wrapping_sub(1);
    }
    v[0] = value;
}

fn MoveToFrontTransform(v_in: &[u32], v_size: usize, v_out: &mut [u32]) {
    let mut mtf: [u8; 256] = [0; 256];
    let mut max_value: u32;
    if v_size == 0usize {
        return;
    }
    max_value = v_in[0];
    for i in 1..v_size {
        if v_in[i] > max_value {
            max_value = v_in[i];
        }
    }
    for i in 0..=max_value as usize {
        mtf[i] = i as u8;
    }
    {
        let mtf_size: usize = max_value.wrapping_add(1) as usize;
        for i in 0usize..v_size {
            let index: usize = IndexOf(&mtf[..], mtf_size, v_in[i] as u8);
            v_out[i] = index as u32;
            MoveToFront(&mut mtf[..], index);
        }
    }
}

fn RunLengthCodeZeros(
    in_size: usize,
    v: &mut [u32],
    out_size: &mut usize,
    max_run_length_prefix: &mut u32,
) {
    let mut max_reps: u32 = 0u32;
    let mut i: usize;
    let mut max_prefix: u32;
    i = 0usize;
    while i < in_size {
        let mut reps: u32 = 0u32;
        while i < in_size && (v[i] != 0u32) {
            i = i.wrapping_add(1);
        }
        while i < in_size && (v[i] == 0u32) {
            {
                reps = reps.wrapping_add(1);
            }
            i = i.wrapping_add(1);
        }
        max_reps = max(reps, max_reps);
    }
    max_prefix = if max_reps > 0u32 {
        Log2FloorNonZero(max_reps as (u64))
    } else {
        0u32
    };
    max_prefix = min(max_prefix, *max_run_length_prefix);
    *max_run_length_prefix = max_prefix;
    *out_size = 0usize;
    i = 0usize;
    while i < in_size {
        if v[i] != 0u32 {
            v[*out_size] = (v[i]).wrapping_add(*max_run_length_prefix);
            i = i.wrapping_add(1);
            *out_size = out_size.wrapping_add(1);
        } else {
            let mut reps: u32 = 1u32;
            let mut k: usize;
            k = i.wrapping_add(1);
            while k < in_size && (v[k] == 0u32) {
                {
                    reps = reps.wrapping_add(1);
                }
                k = k.wrapping_add(1);
            }
            i = i.wrapping_add(reps as usize);
            while reps != 0u32 {
                if reps < 2u32 << max_prefix {
                    let run_length_prefix: u32 = Log2FloorNonZero(reps as (u64));
                    let extra_bits: u32 = reps.wrapping_sub(1u32 << run_length_prefix);
                    v[*out_size] = run_length_prefix.wrapping_add(extra_bits << 9);
                    *out_size = out_size.wrapping_add(1);
                    {
                        break;
                    }
                } else {
                    let extra_bits: u32 = (1u32 << max_prefix).wrapping_sub(1);
                    v[*out_size] = max_prefix.wrapping_add(extra_bits << 9);
                    reps = reps.wrapping_sub((2u32 << max_prefix).wrapping_sub(1));
                    *out_size = out_size.wrapping_add(1);
                }
            }
        }
    }
}

fn EncodeContextMap<AllocU32: alloc::Allocator<u32>>(
    m: &mut AllocU32,
    context_map: &[u32],
    context_map_size: usize,
    num_clusters: usize,
    tree: &mut [HuffmanTree],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut rle_symbols: AllocU32::AllocatedMemory;
    let mut max_run_length_prefix: u32 = 6u32;
    let mut num_rle_symbols: usize = 0usize;
    static kSymbolMask: u32 = (1u32 << 9) - 1;
    let mut depths: [u8; 272] = [0; 272];
    let mut bits: [u16; 272] = [0; 272];
    StoreVarLenUint8(num_clusters.wrapping_sub(1) as u64, storage_ix, storage);
    if num_clusters == 1 {
        return;
    }
    rle_symbols = alloc_or_default::<u32, _>(m, context_map_size);
    MoveToFrontTransform(context_map, context_map_size, rle_symbols.slice_mut());
    RunLengthCodeZeros(
        context_map_size,
        rle_symbols.slice_mut(),
        &mut num_rle_symbols,
        &mut max_run_length_prefix,
    );
    let mut histogram: [u32; 272] = [0; 272];
    for i in 0usize..num_rle_symbols {
        let _rhs = 1;
        let _lhs = &mut histogram[(rle_symbols.slice()[i] & kSymbolMask) as usize];
        *_lhs = (*_lhs).wrapping_add(_rhs as u32);
    }
    {
        let use_rle = max_run_length_prefix > 0;
        BrotliWriteBits(1, u64::from(use_rle), storage_ix, storage);
        if use_rle {
            BrotliWriteBits(
                4,
                max_run_length_prefix.wrapping_sub(1) as (u64),
                storage_ix,
                storage,
            );
        }
    }
    BuildAndStoreHuffmanTree(
        &mut histogram[..],
        num_clusters.wrapping_add(max_run_length_prefix as usize),
        num_clusters.wrapping_add(max_run_length_prefix as usize),
        tree,
        &mut depths[..],
        &mut bits[..],
        storage_ix,
        storage,
    );
    for i in 0usize..num_rle_symbols {
        let rle_symbol: u32 = rle_symbols.slice()[i] & kSymbolMask;
        let extra_bits_val: u32 = rle_symbols.slice()[i] >> 9;
        BrotliWriteBits(
            depths[rle_symbol as usize],
            bits[rle_symbol as usize] as (u64),
            storage_ix,
            storage,
        );
        if rle_symbol > 0u32 && (rle_symbol <= max_run_length_prefix) {
            BrotliWriteBits(
                rle_symbol as u8,
                extra_bits_val as (u64),
                storage_ix,
                storage,
            );
        }
    }
    BrotliWriteBits(1, 1, storage_ix, storage);
    m.free_cell(rle_symbols);
}

impl<Alloc: Allocator<u8> + Allocator<u16>> BlockEncoder<'_, Alloc> {
    fn build_and_store_entropy_codes<HistogramType: SliceWrapper<u32>>(
        &mut self,
        m: &mut Alloc,
        histograms: &[HistogramType],
        histograms_size: usize,
        alphabet_size: usize,
        tree: &mut [HuffmanTree],
        storage_ix: &mut usize,
        storage: &mut [u8],
    ) {
        let table_size: usize = histograms_size.wrapping_mul(self.histogram_length_);
        self.depths_ = alloc_or_default::<u8, _>(m, table_size);
        self.bits_ = alloc_or_default::<u16, _>(m, table_size);
        {
            for i in 0usize..histograms_size {
                let ix: usize = i.wrapping_mul(self.histogram_length_);
                BuildAndStoreHuffmanTree(
                    &(histograms[i]).slice()[0..],
                    self.histogram_length_,
                    alphabet_size,
                    tree,
                    &mut self.depths_.slice_mut()[ix..],
                    &mut self.bits_.slice_mut()[ix..],
                    storage_ix,
                    storage,
                );
            }
        }
    }

    fn store_symbol(&mut self, symbol: usize, storage_ix: &mut usize, storage: &mut [u8]) {
        if self.block_len_ == 0usize {
            let block_ix: usize = {
                self.block_ix_ = self.block_ix_.wrapping_add(1);
                self.block_ix_
            };
            let block_len: u32 = self.block_lengths_[block_ix];
            let block_type: u8 = self.block_types_[block_ix];
            self.block_len_ = block_len as usize;
            self.entropy_ix_ = (block_type as usize).wrapping_mul(self.histogram_length_);
            StoreBlockSwitch(
                &mut self.block_split_code_,
                block_len,
                block_type,
                false,
                storage_ix,
                storage,
            );
        }
        self.block_len_ = self.block_len_.wrapping_sub(1);
        {
            let ix: usize = self.entropy_ix_.wrapping_add(symbol);
            BrotliWriteBits(
                self.depths_.slice()[ix],
                self.bits_.slice()[ix] as (u64),
                storage_ix,
                storage,
            );
        }
    }
}

impl Command {
    fn copy_len_code(&self) -> u32 {
        let modifier = self.copy_len_ >> 25;
        let delta: i32 = ((modifier | ((modifier & 0x40) << 1)) as u8) as i8 as i32;
        ((self.copy_len_ & 0x01ff_ffff) as i32 + delta) as u32
    }
}

fn GetInsertExtra(inscode: u16) -> u32 {
    kInsExtra[inscode as usize]
}

fn GetInsertBase(inscode: u16) -> u32 {
    kInsBase[inscode as usize]
}

fn GetCopyBase(copycode: u16) -> u32 {
    kCopyBase[copycode as usize]
}

fn GetCopyExtra(copycode: u16) -> u32 {
    kCopyExtra[copycode as usize]
}

fn StoreCommandExtra(cmd: &Command, storage_ix: &mut usize, storage: &mut [u8]) {
    let copylen_code = cmd.copy_len_code();
    let inscode: u16 = GetInsertLengthCode(cmd.insert_len_ as usize);
    let copycode: u16 = GetCopyLengthCode(copylen_code as usize);
    let insnumextra: u32 = GetInsertExtra(inscode);
    let insextraval: u64 = cmd.insert_len_.wrapping_sub(GetInsertBase(inscode)) as (u64);
    let copyextraval: u64 = copylen_code.wrapping_sub(GetCopyBase(copycode)) as (u64);
    let bits: u64 = copyextraval << insnumextra | insextraval;
    BrotliWriteBits(
        insnumextra.wrapping_add(GetCopyExtra(copycode)) as u8,
        bits,
        storage_ix,
        storage,
    );
}

fn Context(p1: u8, p2: u8, mode: ContextType) -> u8 {
    match mode {
        ContextType::CONTEXT_LSB6 => (p1 as i32 & 0x3fi32) as u8,
        ContextType::CONTEXT_MSB6 => (p1 as i32 >> 2) as u8,
        ContextType::CONTEXT_UTF8 => {
            (kUTF8ContextLookup[p1 as usize] as i32
                | kUTF8ContextLookup[(p2 as i32 + 256i32) as usize] as i32) as u8
        }
        ContextType::CONTEXT_SIGNED => {
            (((kSigned3BitContextLookup[p1 as usize] as i32) << 3)
                + kSigned3BitContextLookup[p2 as usize] as i32) as u8
        }
    }
    //  0u8
}

impl<Alloc: Allocator<u8> + Allocator<u16>> BlockEncoder<'_, Alloc> {
    fn store_symbol_with_context(
        &mut self,
        symbol: usize,
        context: usize,
        context_map: &[u32],
        storage_ix: &mut usize,
        storage: &mut [u8],
        context_bits: usize,
    ) {
        if self.block_len_ == 0 {
            let block_ix: usize = {
                self.block_ix_ = self.block_ix_.wrapping_add(1);
                self.block_ix_
            };
            let block_len: u32 = self.block_lengths_[block_ix];
            let block_type: u8 = self.block_types_[block_ix];
            self.block_len_ = block_len as usize;
            self.entropy_ix_ = (block_type as usize) << context_bits;
            StoreBlockSwitch(
                &mut self.block_split_code_,
                block_len,
                block_type,
                false,
                storage_ix,
                storage,
            );
        }
        self.block_len_ = self.block_len_.wrapping_sub(1);
        {
            let histo_ix: usize = context_map[self.entropy_ix_.wrapping_add(context)] as usize;
            let ix: usize = histo_ix
                .wrapping_mul(self.histogram_length_)
                .wrapping_add(symbol);
            BrotliWriteBits(
                self.depths_.slice()[ix],
                self.bits_.slice()[ix] as (u64),
                storage_ix,
                storage,
            );
        }
    }
}

impl<Alloc: Allocator<u8> + Allocator<u16>> BlockEncoder<'_, Alloc> {
    fn cleanup(&mut self, m: &mut Alloc) {
        <Alloc as Allocator<u8>>::free_cell(m, core::mem::take(&mut self.depths_));
        <Alloc as Allocator<u16>>::free_cell(m, core::mem::take(&mut self.bits_));
    }
}

pub fn JumpToByteBoundary(storage_ix: &mut usize, storage: &mut [u8]) {
    *storage_ix = storage_ix.wrapping_add(7u32 as usize) & !7u32 as usize;
    storage[(*storage_ix >> 3)] = 0u8;
}

pub(crate) fn store_meta_block<Alloc: BrotliAlloc, Cb>(
    alloc: &mut Alloc,
    input: &[u8],
    start_pos: usize,
    length: usize,
    mask: usize,
    mut prev_byte: u8,
    mut prev_byte2: u8,
    is_last: bool,
    params: &BrotliEncoderParams,
    literal_context_mode: ContextType,
    distance_cache: &[i32; kNumDistanceCacheEntries],
    commands: &[Command],
    n_commands: usize,
    mb: &mut MetaBlockSplit<Alloc>,
    recoder_state: &mut RecoderState,
    storage_ix: &mut usize,
    storage: &mut [u8],
    callback: &mut Cb,
) where
    Cb: FnMut(
        &mut interface::PredictionModeContextMap<InputReferenceMut>,
        &mut [interface::StaticCommand],
        InputPair,
        &mut Alloc,
    ),
{
    let (input0, input1) = InputPairFromMaskedInput(input, start_pos, length, mask);
    if params.log_meta_block {
        LogMetaBlock(
            alloc,
            commands.split_at(n_commands).0,
            input0,
            input1,
            distance_cache,
            recoder_state,
            block_split_reference(mb),
            params,
            Some(literal_context_mode),
            callback,
        );
    }
    let mut pos: usize = start_pos;
    let num_distance_symbols = params.dist.alphabet_size;
    let mut num_effective_distance_symbols = num_distance_symbols as usize;
    let _literal_context_lut = BROTLI_CONTEXT_LUT(literal_context_mode);
    let mut literal_enc: BlockEncoder<Alloc>;
    let mut command_enc: BlockEncoder<Alloc>;
    let mut distance_enc: BlockEncoder<Alloc>;
    let dist = &params.dist;
    if params.large_window && num_effective_distance_symbols > BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS
    {
        num_effective_distance_symbols = BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS;
    }
    StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
    let mut tree = allocate::<HuffmanTree, _>(alloc, 2 * 704 + 1);
    literal_enc = BlockEncoder::new(
        BROTLI_NUM_LITERAL_SYMBOLS,
        mb.literal_split.num_types,
        mb.literal_split.types.slice(),
        mb.literal_split.lengths.slice(),
        mb.literal_split.num_blocks,
    );
    command_enc = BlockEncoder::new(
        BROTLI_NUM_COMMAND_SYMBOLS,
        mb.command_split.num_types,
        mb.command_split.types.slice(),
        mb.command_split.lengths.slice(),
        mb.command_split.num_blocks,
    );
    distance_enc = BlockEncoder::new(
        num_effective_distance_symbols,
        mb.distance_split.num_types,
        mb.distance_split.types.slice(),
        mb.distance_split.lengths.slice(),
        mb.distance_split.num_blocks,
    );
    literal_enc.build_and_store_block_switch_entropy_codes(tree.slice_mut(), storage_ix, storage);
    command_enc.build_and_store_block_switch_entropy_codes(tree.slice_mut(), storage_ix, storage);
    distance_enc.build_and_store_block_switch_entropy_codes(tree.slice_mut(), storage_ix, storage);
    BrotliWriteBits(2, dist.distance_postfix_bits as (u64), storage_ix, storage);
    BrotliWriteBits(
        4,
        (dist.num_direct_distance_codes >> dist.distance_postfix_bits) as (u64),
        storage_ix,
        storage,
    );
    for _i in 0usize..mb.literal_split.num_types {
        BrotliWriteBits(2, literal_context_mode as (u64), storage_ix, storage);
    }
    if mb.literal_context_map_size == 0usize {
        StoreTrivialContextMap(
            mb.literal_histograms_size,
            6,
            tree.slice_mut(),
            storage_ix,
            storage,
        );
    } else {
        EncodeContextMap(
            alloc,
            mb.literal_context_map.slice(),
            mb.literal_context_map_size,
            mb.literal_histograms_size,
            tree.slice_mut(),
            storage_ix,
            storage,
        );
    }
    if mb.distance_context_map_size == 0usize {
        StoreTrivialContextMap(
            mb.distance_histograms_size,
            2usize,
            tree.slice_mut(),
            storage_ix,
            storage,
        );
    } else {
        EncodeContextMap(
            alloc,
            mb.distance_context_map.slice(),
            mb.distance_context_map_size,
            mb.distance_histograms_size,
            tree.slice_mut(),
            storage_ix,
            storage,
        );
    }
    literal_enc.build_and_store_entropy_codes(
        alloc,
        mb.literal_histograms.slice(),
        mb.literal_histograms_size,
        BROTLI_NUM_LITERAL_SYMBOLS,
        tree.slice_mut(),
        storage_ix,
        storage,
    );
    command_enc.build_and_store_entropy_codes(
        alloc,
        mb.command_histograms.slice(),
        mb.command_histograms_size,
        BROTLI_NUM_COMMAND_SYMBOLS,
        tree.slice_mut(),
        storage_ix,
        storage,
    );
    distance_enc.build_and_store_entropy_codes(
        alloc,
        mb.distance_histograms.slice(),
        mb.distance_histograms_size,
        num_distance_symbols as usize,
        tree.slice_mut(),
        storage_ix,
        storage,
    );
    {
        <Alloc as Allocator<HuffmanTree>>::free_cell(alloc, core::mem::take(&mut tree));
    }
    for i in 0usize..n_commands {
        let cmd: Command = commands[i];
        let cmd_code: usize = cmd.cmd_prefix_ as usize;
        command_enc.store_symbol(cmd_code, storage_ix, storage);
        StoreCommandExtra(&cmd, storage_ix, storage);
        if mb.literal_context_map_size == 0usize {
            let mut j: usize;
            j = cmd.insert_len_ as usize;
            while j != 0usize {
                {
                    literal_enc.store_symbol(input[(pos & mask)] as usize, storage_ix, storage);
                    pos = pos.wrapping_add(1);
                }
                j = j.wrapping_sub(1);
            }
        } else {
            let mut j: usize;
            j = cmd.insert_len_ as usize;
            while j != 0usize {
                {
                    let context: usize =
                        Context(prev_byte, prev_byte2, literal_context_mode) as usize;
                    let literal: u8 = input[(pos & mask)];
                    literal_enc.store_symbol_with_context(
                        literal as usize,
                        context,
                        mb.literal_context_map.slice(),
                        storage_ix,
                        storage,
                        6usize,
                    );
                    prev_byte2 = prev_byte;
                    prev_byte = literal;
                    pos = pos.wrapping_add(1);
                }
                j = j.wrapping_sub(1);
            }
        }
        pos = pos.wrapping_add(cmd.copy_len() as usize);
        if cmd.copy_len() != 0 {
            prev_byte2 = input[(pos.wrapping_sub(2) & mask)];
            prev_byte = input[(pos.wrapping_sub(1) & mask)];
            if cmd.cmd_prefix_ as i32 >= 128i32 {
                let dist_code: usize = cmd.dist_prefix_ as usize & 0x03ff;
                let distnumextra: u32 = u32::from(cmd.dist_prefix_) >> 10; //FIXME: from command
                let distextra: u64 = cmd.dist_extra_ as (u64);
                if mb.distance_context_map_size == 0usize {
                    distance_enc.store_symbol(dist_code, storage_ix, storage);
                } else {
                    distance_enc.store_symbol_with_context(
                        dist_code,
                        cmd.distance_context() as usize,
                        mb.distance_context_map.slice(),
                        storage_ix,
                        storage,
                        2usize,
                    );
                }
                BrotliWriteBits(distnumextra as u8, distextra, storage_ix, storage);
            }
        }
    }
    distance_enc.cleanup(alloc);
    command_enc.cleanup(alloc);
    literal_enc.cleanup(alloc);
    if is_last {
        JumpToByteBoundary(storage_ix, storage);
    }
}

fn BuildHistograms(
    input: &[u8],
    start_pos: usize,
    mask: usize,
    commands: &[Command],
    n_commands: usize,
    lit_histo: &mut HistogramLiteral,
    cmd_histo: &mut HistogramCommand,
    dist_histo: &mut HistogramDistance,
) {
    let mut pos: usize = start_pos;
    for i in 0usize..n_commands {
        let cmd: Command = commands[i];
        let mut j: usize;
        HistogramAddItem(cmd_histo, cmd.cmd_prefix_ as usize);
        j = cmd.insert_len_ as usize;
        while j != 0usize {
            {
                HistogramAddItem(lit_histo, input[(pos & mask)] as usize);
                pos = pos.wrapping_add(1);
            }
            j = j.wrapping_sub(1);
        }
        pos = pos.wrapping_add(cmd.copy_len() as usize);
        if cmd.copy_len() != 0 && cmd.cmd_prefix_ >= 128 {
            HistogramAddItem(dist_histo, cmd.dist_prefix_ as usize & 0x03ff);
        }
    }
}
fn StoreDataWithHuffmanCodes(
    input: &[u8],
    start_pos: usize,
    mask: usize,
    commands: &[Command],
    n_commands: usize,
    lit_depth: &[u8],
    lit_bits: &[u16],
    cmd_depth: &[u8],
    cmd_bits: &[u16],
    dist_depth: &[u8],
    dist_bits: &[u16],
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut pos: usize = start_pos;
    for i in 0usize..n_commands {
        let cmd: Command = commands[i];
        let cmd_code: usize = cmd.cmd_prefix_ as usize;
        let mut j: usize;
        BrotliWriteBits(
            cmd_depth[cmd_code],
            cmd_bits[cmd_code] as (u64),
            storage_ix,
            storage,
        );
        StoreCommandExtra(&cmd, storage_ix, storage);
        j = cmd.insert_len_ as usize;
        while j != 0usize {
            {
                let literal: u8 = input[(pos & mask)];
                BrotliWriteBits(
                    lit_depth[(literal as usize)],
                    lit_bits[(literal as usize)] as (u64),
                    storage_ix,
                    storage,
                );
                pos = pos.wrapping_add(1);
            }
            j = j.wrapping_sub(1);
        }
        pos = pos.wrapping_add(cmd.copy_len() as usize);
        if cmd.copy_len() != 0 && cmd.cmd_prefix_ >= 128 {
            let dist_code: usize = cmd.dist_prefix_ as usize & 0x03ff;
            let distnumextra: u32 = u32::from(cmd.dist_prefix_) >> 10;
            let distextra: u32 = cmd.dist_extra_;
            BrotliWriteBits(
                dist_depth[dist_code],
                dist_bits[dist_code] as (u64),
                storage_ix,
                storage,
            );
            BrotliWriteBits(distnumextra as u8, distextra as (u64), storage_ix, storage);
        }
    }
}

pub(crate) fn store_meta_block_trivial<Alloc: BrotliAlloc, Cb>(
    alloc: &mut Alloc,
    input: &[u8],
    start_pos: usize,
    length: usize,
    mask: usize,
    is_last: bool,
    params: &BrotliEncoderParams,
    distance_cache: &[i32; kNumDistanceCacheEntries],
    commands: &[Command],
    n_commands: usize,
    recoder_state: &mut RecoderState,
    storage_ix: &mut usize,
    storage: &mut [u8],
    f: &mut Cb,
) where
    Cb: FnMut(
        &mut interface::PredictionModeContextMap<InputReferenceMut>,
        &mut [interface::StaticCommand],
        InputPair,
        &mut Alloc,
    ),
{
    let (input0, input1) = InputPairFromMaskedInput(input, start_pos, length, mask);
    if params.log_meta_block {
        LogMetaBlock(
            alloc,
            commands.split_at(n_commands).0,
            input0,
            input1,
            distance_cache,
            recoder_state,
            block_split_nop(),
            params,
            Some(ContextType::CONTEXT_LSB6),
            f,
        );
    }
    let mut lit_histo: HistogramLiteral = HistogramLiteral::default();
    let mut cmd_histo: HistogramCommand = HistogramCommand::default();
    let mut dist_histo: HistogramDistance = HistogramDistance::default();
    let mut lit_depth: [u8; 256] = [0; 256];
    let mut lit_bits: [u16; 256] = [0; 256];
    let mut cmd_depth: [u8; 704] = [0; 704];
    let mut cmd_bits: [u16; 704] = [0; 704];
    let mut dist_depth: [u8; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE] =
        [0; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
    let mut dist_bits: [u16; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE] =
        [0; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
    const MAX_HUFFMAN_TREE_SIZE: usize = (2i32 * 704i32 + 1i32) as usize;
    let mut tree: [HuffmanTree; MAX_HUFFMAN_TREE_SIZE] = [HuffmanTree {
        total_count_: 0,
        index_left_: 0,
        index_right_or_value_: 0,
    }; MAX_HUFFMAN_TREE_SIZE];
    let num_distance_symbols = params.dist.alphabet_size;
    StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
    BuildHistograms(
        input,
        start_pos,
        mask,
        commands,
        n_commands,
        &mut lit_histo,
        &mut cmd_histo,
        &mut dist_histo,
    );
    BrotliWriteBits(13, 0, storage_ix, storage);
    BuildAndStoreHuffmanTree(
        lit_histo.slice_mut(),
        BROTLI_NUM_LITERAL_SYMBOLS,
        BROTLI_NUM_LITERAL_SYMBOLS,
        &mut tree[..],
        &mut lit_depth[..],
        &mut lit_bits[..],
        storage_ix,
        storage,
    );
    BuildAndStoreHuffmanTree(
        cmd_histo.slice_mut(),
        BROTLI_NUM_COMMAND_SYMBOLS,
        BROTLI_NUM_COMMAND_SYMBOLS,
        &mut tree[..],
        &mut cmd_depth[..],
        &mut cmd_bits[..],
        storage_ix,
        storage,
    );
    BuildAndStoreHuffmanTree(
        dist_histo.slice_mut(),
        MAX_SIMPLE_DISTANCE_ALPHABET_SIZE,
        num_distance_symbols as usize,
        &mut tree[..],
        &mut dist_depth[..],
        &mut dist_bits[..],
        storage_ix,
        storage,
    );
    StoreDataWithHuffmanCodes(
        input,
        start_pos,
        mask,
        commands,
        n_commands,
        &mut lit_depth[..],
        &mut lit_bits[..],
        &mut cmd_depth[..],
        &mut cmd_bits[..],
        &mut dist_depth[..],
        &mut dist_bits[..],
        storage_ix,
        storage,
    );
    if is_last {
        JumpToByteBoundary(storage_ix, storage);
    }
}

fn StoreStaticCommandHuffmanTree(storage_ix: &mut usize, storage: &mut [u8]) {
    BrotliWriteBits(56, 0x0092_6244_1630_7003, storage_ix, storage);
    BrotliWriteBits(3, 0, storage_ix, storage);
}

fn StoreStaticDistanceHuffmanTree(storage_ix: &mut usize, storage: &mut [u8]) {
    BrotliWriteBits(28, 0x0369_dc03, storage_ix, storage);
}

struct BlockSplitRef<'a> {
    types: &'a [u8],
    lengths: &'a [u32],
    num_types: u32,
}

impl<'a> Default for BlockSplitRef<'a> {
    fn default() -> Self {
        BlockSplitRef {
            types: &[],
            lengths: &[],
            num_types: 1,
        }
    }
}

#[derive(Default)]
struct MetaBlockSplitRefs<'a> {
    btypel: BlockSplitRef<'a>,
    literal_context_map: &'a [u32],
    btypec: BlockSplitRef<'a>,
    btyped: BlockSplitRef<'a>,
    distance_context_map: &'a [u32],
}

fn block_split_nop() -> MetaBlockSplitRefs<'static> {
    MetaBlockSplitRefs::default()
}

fn block_split_reference<'a, Alloc: BrotliAlloc>(
    mb: &'a MetaBlockSplit<Alloc>,
) -> MetaBlockSplitRefs<'a> {
    return MetaBlockSplitRefs::<'a> {
        btypel: BlockSplitRef {
            types: mb
                .literal_split
                .types
                .slice()
                .split_at(mb.literal_split.num_blocks)
                .0,
            lengths: mb
                .literal_split
                .lengths
                .slice()
                .split_at(mb.literal_split.num_blocks)
                .0,
            num_types: mb.literal_split.num_types as u32,
        },
        literal_context_map: mb
            .literal_context_map
            .slice()
            .split_at(mb.literal_context_map_size)
            .0,
        btypec: BlockSplitRef {
            types: mb
                .command_split
                .types
                .slice()
                .split_at(mb.command_split.num_blocks)
                .0,
            lengths: mb
                .command_split
                .lengths
                .slice()
                .split_at(mb.command_split.num_blocks)
                .0,
            num_types: mb.command_split.num_types as u32,
        },
        btyped: BlockSplitRef {
            types: mb
                .distance_split
                .types
                .slice()
                .split_at(mb.distance_split.num_blocks)
                .0,
            lengths: mb
                .distance_split
                .lengths
                .slice()
                .split_at(mb.distance_split.num_blocks)
                .0,
            num_types: mb.distance_split.num_types as u32,
        },
        distance_context_map: mb
            .distance_context_map
            .slice()
            .split_at(mb.distance_context_map_size)
            .0,
    };
}

#[derive(Clone, Copy, Default)]
pub struct RecoderState {
    pub num_bytes_encoded: usize,
}

impl RecoderState {
    pub fn new() -> Self {
        Self::default()
    }
}

pub(crate) fn store_meta_block_fast<Cb, Alloc: BrotliAlloc>(
    m: &mut Alloc,
    input: &[u8],
    start_pos: usize,
    length: usize,
    mask: usize,
    is_last: bool,
    params: &BrotliEncoderParams,
    dist_cache: &[i32; kNumDistanceCacheEntries],
    commands: &[Command],
    n_commands: usize,
    recoder_state: &mut RecoderState,
    storage_ix: &mut usize,
    storage: &mut [u8],
    cb: &mut Cb,
) where
    Cb: FnMut(
        &mut interface::PredictionModeContextMap<InputReferenceMut>,
        &mut [StaticCommand],
        InputPair,
        &mut Alloc,
    ),
{
    let (input0, input1) = InputPairFromMaskedInput(input, start_pos, length, mask);
    if params.log_meta_block {
        LogMetaBlock(
            m,
            commands.split_at(n_commands).0,
            input0,
            input1,
            dist_cache,
            recoder_state,
            block_split_nop(),
            params,
            Some(ContextType::CONTEXT_LSB6),
            cb,
        );
    }
    let num_distance_symbols = params.dist.alphabet_size;
    let distance_alphabet_bits = Log2FloorNonZero(u64::from(num_distance_symbols) - 1) + 1;
    StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
    BrotliWriteBits(13, 0, storage_ix, storage);
    if n_commands <= 128usize {
        let mut histogram: [u32; 256] = [0; 256];
        let mut pos: usize = start_pos;
        let mut num_literals: usize = 0usize;
        let mut lit_depth: [u8; 256] = [0; 256];
        let mut lit_bits: [u16; 256] = [0; 256];
        for i in 0usize..n_commands {
            let cmd: Command = commands[i];
            let mut j: usize;
            j = cmd.insert_len_ as usize;
            while j != 0usize {
                {
                    {
                        let _rhs = 1;
                        let _lhs = &mut histogram[input[(pos & mask)] as usize];
                        *_lhs = (*_lhs).wrapping_add(_rhs as u32);
                    }
                    pos = pos.wrapping_add(1);
                }
                j = j.wrapping_sub(1);
            }
            num_literals = num_literals.wrapping_add(cmd.insert_len_ as usize);
            pos = pos.wrapping_add(cmd.copy_len() as usize);
        }
        BrotliBuildAndStoreHuffmanTreeFast(
            m,
            &mut histogram[..],
            num_literals,
            8usize,
            &mut lit_depth[..],
            &mut lit_bits[..],
            storage_ix,
            storage,
        );
        StoreStaticCommandHuffmanTree(storage_ix, storage);
        StoreStaticDistanceHuffmanTree(storage_ix, storage);
        StoreDataWithHuffmanCodes(
            input,
            start_pos,
            mask,
            commands,
            n_commands,
            &mut lit_depth[..],
            &mut lit_bits[..],
            &kStaticCommandCodeDepth[..],
            &kStaticCommandCodeBits[..],
            &kStaticDistanceCodeDepth[..],
            &kStaticDistanceCodeBits[..],
            storage_ix,
            storage,
        );
    } else {
        let mut lit_histo: HistogramLiteral = HistogramLiteral::default();
        let mut cmd_histo: HistogramCommand = HistogramCommand::default();
        let mut dist_histo: HistogramDistance = HistogramDistance::default();
        let mut lit_depth: [u8; 256] = [0; 256];
        let mut lit_bits: [u16; 256] = [0; 256];
        let mut cmd_depth: [u8; 704] = [0; 704];
        let mut cmd_bits: [u16; 704] = [0; 704];
        let mut dist_depth: [u8; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE] =
            [0; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
        let mut dist_bits: [u16; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE] =
            [0; MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
        BuildHistograms(
            input,
            start_pos,
            mask,
            commands,
            n_commands,
            &mut lit_histo,
            &mut cmd_histo,
            &mut dist_histo,
        );
        BrotliBuildAndStoreHuffmanTreeFast(
            m,
            lit_histo.slice(),
            lit_histo.total_count_,
            8usize,
            &mut lit_depth[..],
            &mut lit_bits[..],
            storage_ix,
            storage,
        );
        BrotliBuildAndStoreHuffmanTreeFast(
            m,
            cmd_histo.slice(),
            cmd_histo.total_count_,
            10usize,
            &mut cmd_depth[..],
            &mut cmd_bits[..],
            storage_ix,
            storage,
        );
        BrotliBuildAndStoreHuffmanTreeFast(
            m,
            dist_histo.slice(),
            dist_histo.total_count_,
            distance_alphabet_bits as usize,
            &mut dist_depth[..],
            &mut dist_bits[..],
            storage_ix,
            storage,
        );
        StoreDataWithHuffmanCodes(
            input,
            start_pos,
            mask,
            commands,
            n_commands,
            &mut lit_depth[..],
            &mut lit_bits[..],
            &mut cmd_depth[..],
            &mut cmd_bits[..],
            &mut dist_depth[..],
            &mut dist_bits[..],
            storage_ix,
            storage,
        );
    }
    if is_last {
        JumpToByteBoundary(storage_ix, storage);
    }
}
fn BrotliStoreUncompressedMetaBlockHeader(
    length: usize,
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    let mut lenbits: u64 = 0;
    let mut nlenbits: u32 = 0;
    let mut nibblesbits: u32 = 0;
    BrotliWriteBits(1, 0, storage_ix, storage);
    BrotliEncodeMlen(length as u32, &mut lenbits, &mut nlenbits, &mut nibblesbits);
    BrotliWriteBits(2, nibblesbits as u64, storage_ix, storage);
    BrotliWriteBits(nlenbits as u8, lenbits, storage_ix, storage);
    BrotliWriteBits(1, 1, storage_ix, storage);
}

fn InputPairFromMaskedInput(
    input: &[u8],
    position: usize,
    len: usize,
    mask: usize,
) -> (&[u8], &[u8]) {
    let masked_pos: usize = position & mask;
    if masked_pos.wrapping_add(len) > mask.wrapping_add(1) {
        let len1: usize = mask.wrapping_add(1).wrapping_sub(masked_pos);
        return (
            &input[masked_pos..(masked_pos + len1)],
            &input[0..len.wrapping_sub(len1)],
        );
    }
    (&input[masked_pos..masked_pos + len], &[])
}

pub(crate) fn store_uncompressed_meta_block<Cb, Alloc: BrotliAlloc>(
    alloc: &mut Alloc,
    is_final_block: bool,
    input: &[u8],
    position: usize,
    mask: usize,
    params: &BrotliEncoderParams,
    len: usize,
    recoder_state: &mut RecoderState,
    storage_ix: &mut usize,
    storage: &mut [u8],
    suppress_meta_block_logging: bool,
    cb: &mut Cb,
) where
    Cb: FnMut(
        &mut interface::PredictionModeContextMap<InputReferenceMut>,
        &mut [StaticCommand],
        InputPair,
        &mut Alloc,
    ),
{
    let (input0, input1) = InputPairFromMaskedInput(input, position, len, mask);
    BrotliStoreUncompressedMetaBlockHeader(len, storage_ix, storage);
    JumpToByteBoundary(storage_ix, storage);
    let dst_start0 = (*storage_ix >> 3);
    storage[dst_start0..(dst_start0 + input0.len())].clone_from_slice(input0);
    *storage_ix = storage_ix.wrapping_add(input0.len() << 3);
    let dst_start1 = (*storage_ix >> 3);
    storage[dst_start1..(dst_start1 + input1.len())].clone_from_slice(input1);
    *storage_ix = storage_ix.wrapping_add(input1.len() << 3);
    BrotliWriteBitsPrepareStorage(*storage_ix, storage);
    if params.log_meta_block && !suppress_meta_block_logging {
        let cmds = [Command {
            insert_len_: len as u32,
            copy_len_: 0,
            dist_extra_: 0,
            cmd_prefix_: 0,
            dist_prefix_: 0,
        }];

        LogMetaBlock(
            alloc,
            &cmds,
            input0,
            input1,
            &[0, 0, 0, 0],
            recoder_state,
            block_split_nop(),
            params,
            None,
            cb,
        );
    }
    if is_final_block {
        BrotliWriteBits(1u8, 1u64, storage_ix, storage);
        BrotliWriteBits(1u8, 1u64, storage_ix, storage);
        JumpToByteBoundary(storage_ix, storage);
    }
}

pub fn BrotliStoreSyncMetaBlock(storage_ix: &mut usize, storage: &mut [u8]) {
    BrotliWriteBits(6, 6, storage_ix, storage);
    JumpToByteBoundary(storage_ix, storage);
}

pub fn BrotliWriteEmptyLastMetaBlock(storage_ix: &mut usize, storage: &mut [u8]) {
    BrotliWriteBits(1u8, 1u64, storage_ix, storage);
    BrotliWriteBits(1u8, 1u64, storage_ix, storage);
    JumpToByteBoundary(storage_ix, storage);
}

const MAX_SIZE_ENCODING: usize = 10;

fn encode_base_128(mut value: u64) -> (usize, [u8; MAX_SIZE_ENCODING]) {
    let mut ret = [0u8; MAX_SIZE_ENCODING];
    for index in 0..ret.len() {
        ret[index] = (value & 0x7f) as u8;
        value >>= 7;
        if value != 0 {
            ret[index] |= 0x80;
        } else {
            return (index + 1, ret);
        }
    }
    (ret.len(), ret)
}

pub fn BrotliWriteMetadataMetaBlock(
    params: &BrotliEncoderParams,
    storage_ix: &mut usize,
    storage: &mut [u8],
) {
    BrotliWriteBits(1u8, 0u64, storage_ix, storage); // not last
    BrotliWriteBits(2u8, 3u64, storage_ix, storage); // MNIBBLES = 0 (pattern 1,1)
    BrotliWriteBits(1u8, 0u64, storage_ix, storage); // reserved
    BrotliWriteBits(2u8, 1u64, storage_ix, storage); // num bytes for length of magic number header
    let (size_hint_count, size_hint_b128) = encode_base_128(params.size_hint as u64);

    BrotliWriteBits(8u8, 3 + size_hint_count as u64, storage_ix, storage); // 1 byte of data: writing 12 for the magic number header
    JumpToByteBoundary(storage_ix, storage);
    let magic_number: [u8; 3] = if params.catable && !params.use_dictionary {
        [0xe1, 0x97, 0x81]
    } else if params.appendable {
        [0xe1, 0x97, 0x82]
    } else {
        [0xe1, 0x97, 0x80]
    };
    for magic in magic_number.iter() {
        BrotliWriteBits(8u8, u64::from(*magic), storage_ix, storage);
    }
    BrotliWriteBits(8u8, u64::from(VERSION), storage_ix, storage);
    for sh in size_hint_b128[..size_hint_count].iter() {
        BrotliWriteBits(8u8, u64::from(*sh), storage_ix, storage);
    }
}

#[cfg(test)]
mod test {
    use crate::enc::brotli_bit_stream::{encode_base_128, MAX_SIZE_ENCODING};

    #[test]
    fn test_encode_base_128() {
        assert_eq!(encode_base_128(0), (1, [0u8; MAX_SIZE_ENCODING]));
        assert_eq!(encode_base_128(1), (1, [1, 0, 0, 0, 0, 0, 0, 0, 0, 0]));
        assert_eq!(encode_base_128(127), (1, [0x7f, 0, 0, 0, 0, 0, 0, 0, 0, 0]));
        assert_eq!(
            encode_base_128(128),
            (2, [0x80, 0x1, 0, 0, 0, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(16383),
            (2, [0xff, 0x7f, 0, 0, 0, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(16384),
            (3, [0x80, 0x80, 0x1, 0, 0, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(2097151),
            (3, [0xff, 0xff, 0x7f, 0, 0, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(2097152),
            (4, [0x80, 0x80, 0x80, 0x1, 0, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(4194303),
            (4, [0xff, 0xff, 0xff, 0x1, 0, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(4294967295),
            (5, [0xff, 0xff, 0xff, 0xff, 0xf, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(4294967296),
            (5, [0x80, 0x80, 0x80, 0x80, 0x10, 0, 0, 0, 0, 0])
        );
        assert_eq!(
            encode_base_128(9223372036854775808),
            (
                10,
                [0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x1]
            )
        );
        assert_eq!(
            encode_base_128(18446744073709551615),
            (
                10,
                [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1]
            )
        );
    }
}