1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
use crate::convert::*;
#[allow(unused)]
use zerocopy::transmute;

///This constant comes from Kunth's prng (Empirically it works better than those from splitmix32).
pub(crate) const MULTIPLE: u64 = 6364136223846793005;

/// This is a constant with a lot of special properties found by automated search.
/// See the unit tests below. (Below are alternative values)
#[cfg(all(target_feature = "ssse3", not(miri)))]
const SHUFFLE_MASK: u128 = 0x020a0700_0c01030e_050f0d08_06090b04_u128;
//const SHUFFLE_MASK: u128 = 0x000d0702_0a040301_05080f0c_0e0b0609_u128;
//const SHUFFLE_MASK: u128 = 0x040A0700_030E0106_0D050F08_020B0C09_u128;

#[inline(always)]
#[cfg(feature = "folded_multiply")]
pub(crate) const fn folded_multiply(s: u64, by: u64) -> u64 {
    let result = (s as u128).wrapping_mul(by as u128);
    ((result & 0xffff_ffff_ffff_ffff) as u64) ^ ((result >> 64) as u64)
}

#[inline(always)]
#[cfg(not(feature = "folded_multiply"))]
pub(crate) const fn folded_multiply(s: u64, by: u64) -> u64 {
    let b1 = s.wrapping_mul(by.swap_bytes());
    let b2 = s.swap_bytes().wrapping_mul(!by);
    b1 ^ b2.swap_bytes()
}

/// Given a small (less than 8 byte slice) returns the same data stored in two u32s.
/// (order of and non-duplication of bytes is NOT guaranteed)
#[inline(always)]
pub(crate) fn read_small(data: &[u8]) -> [u64; 2] {
    debug_assert!(data.len() <= 8);
    if data.len() >= 2 {
        if data.len() >= 4 {
            //len 4-8
            [data.read_u32().0 as u64, data.read_last_u32() as u64]
        } else {
            //len 2-3
            [data.read_u16().0 as u64, data[data.len() - 1] as u64]
        }
    } else {
        if data.len() > 0 {
            [data[0] as u64, data[0] as u64]
        } else {
            [0, 0]
        }
    }
}

#[inline(always)]
pub(crate) fn shuffle(a: u128) -> u128 {
    #[cfg(all(target_feature = "ssse3", not(miri)))]
    {
        #[cfg(target_arch = "x86")]
        use core::arch::x86::*;
        #[cfg(target_arch = "x86_64")]
        use core::arch::x86_64::*;
        unsafe { transmute!(_mm_shuffle_epi8(transmute!(a), transmute!(SHUFFLE_MASK))) }
    }
    #[cfg(not(all(target_feature = "ssse3", not(miri))))]
    {
        a.swap_bytes()
    }
}

#[allow(unused)] //not used by fallback
#[inline(always)]
pub(crate) fn add_and_shuffle(a: u128, b: u128) -> u128 {
    let sum = add_by_64s(a.convert(), b.convert());
    shuffle(sum.convert())
}

#[allow(unused)] //not used by fallback
#[inline(always)]
pub(crate) fn shuffle_and_add(base: u128, to_add: u128) -> u128 {
    let shuffled: [u64; 2] = shuffle(base).convert();
    add_by_64s(shuffled, to_add.convert()).convert()
}

#[cfg(all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "sse2", not(miri)))]
#[inline(always)]
pub(crate) fn add_by_64s(a: [u64; 2], b: [u64; 2]) -> [u64; 2] {
    unsafe {
        #[cfg(target_arch = "x86")]
        use core::arch::x86::*;
        #[cfg(target_arch = "x86_64")]
        use core::arch::x86_64::*;
        transmute!(_mm_add_epi64(transmute!(a), transmute!(b)))
    }
}

#[cfg(not(all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "sse2", not(miri))))]
#[inline(always)]
pub(crate) fn add_by_64s(a: [u64; 2], b: [u64; 2]) -> [u64; 2] {
    [a[0].wrapping_add(b[0]), a[1].wrapping_add(b[1])]
}

#[cfg(all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "aes", not(miri)))]
#[allow(unused)]
#[inline(always)]
pub(crate) fn aesenc(value: u128, xor: u128) -> u128 {
    #[cfg(target_arch = "x86")]
    use core::arch::x86::*;
    #[cfg(target_arch = "x86_64")]
    use core::arch::x86_64::*;
    unsafe {
        let value = transmute!(value);
        transmute!(_mm_aesenc_si128(value, transmute!(xor)))
    }
}

#[cfg(any(
    all(feature = "nightly-arm-aes", target_arch = "aarch64", target_feature = "aes", not(miri)),
    all(feature = "nightly-arm-aes", target_arch = "arm", target_feature = "aes", not(miri)),
))]
#[allow(unused)]
#[inline(always)]
pub(crate) fn aesenc(value: u128, xor: u128) -> u128 {
    #[cfg(target_arch = "aarch64")]
    use core::arch::aarch64::*;
    #[cfg(target_arch = "arm")]
    use core::arch::arm::*;
    let res = unsafe { vaesmcq_u8(vaeseq_u8(transmute!(value), transmute!(0u128))) };
    let value: u128 = transmute!(res);
    xor ^ value
}

#[cfg(all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "aes", not(miri)))]
#[allow(unused)]
#[inline(always)]
pub(crate) fn aesdec(value: u128, xor: u128) -> u128 {
    #[cfg(target_arch = "x86")]
    use core::arch::x86::*;
    #[cfg(target_arch = "x86_64")]
    use core::arch::x86_64::*;
    unsafe {
        let value = transmute!(value);
        transmute!(_mm_aesdec_si128(value, transmute!(xor)))
    }
}

#[cfg(any(
    all(feature = "nightly-arm-aes", target_arch = "aarch64", target_feature = "aes", not(miri)),
    all(feature = "nightly-arm-aes", target_arch = "arm", target_feature = "aes", not(miri)),
))]
#[allow(unused)]
#[inline(always)]
pub(crate) fn aesdec(value: u128, xor: u128) -> u128 {
    #[cfg(target_arch = "aarch64")]
    use core::arch::aarch64::*;
    #[cfg(target_arch = "arm")]
    use core::arch::arm::*;
    let res = unsafe { vaesimcq_u8(vaesdq_u8(transmute!(value), transmute!(0u128))) };
    let value: u128 = transmute!(res);
    xor ^ value
}

#[allow(unused)]
#[inline(always)]
pub(crate) fn add_in_length(enc: &mut u128, len: u64) {
    #[cfg(all(target_arch = "x86_64", target_feature = "sse2", not(miri)))]
    {
        #[cfg(target_arch = "x86_64")]
        use core::arch::x86_64::*;

        unsafe {
            let enc = enc as *mut u128;
            let len = _mm_cvtsi64_si128(len as i64);
            let data = _mm_loadu_si128(enc.cast());
            let sum = _mm_add_epi64(data, len);
            _mm_storeu_si128(enc.cast(), sum);
        }
    }
    #[cfg(not(all(target_arch = "x86_64", target_feature = "sse2", not(miri))))]
    {
        let mut t: [u64; 2] = enc.convert();
        t[0] = t[0].wrapping_add(len);
        *enc = t.convert();
    }
}

#[cfg(test)]
mod test {
    use super::*;

    // This is code to search for the shuffle constant
    //
    //thread_local! { static MASK: Cell<u128> = Cell::new(0); }
    //
    // fn shuffle(a: u128) -> u128 {
    //     use std::intrinsics::transmute;
    //     #[cfg(target_arch = "x86")]
    //     use core::arch::x86::*;
    //     #[cfg(target_arch = "x86_64")]
    //     use core::arch::x86_64::*;
    //     MASK.with(|mask| {
    //         unsafe { transmute!(_mm_shuffle_epi8(transmute!(a), transmute!(mask.get()))) }
    //     })
    // }
    //
    // #[test]
    // fn find_shuffle() {
    //     use rand::prelude::*;
    //     use SliceRandom;
    //     use std::panic;
    //     use std::io::Write;
    //
    //     let mut value: [u8; 16] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ,13, 14, 15];
    //     let mut rand = thread_rng();
    //     let mut successful_list = HashMap::new();
    //     for _attempt in 0..10000000 {
    //         rand.shuffle(&mut value);
    //         let test_val = value.convert();
    //         MASK.with(|mask| {
    //             mask.set(test_val);
    //         });
    //         if let Ok(successful) = panic::catch_unwind(|| {
    //             test_shuffle_does_not_collide_with_aes();
    //             test_shuffle_moves_high_bits();
    //             test_shuffle_moves_every_value();
    //             //test_shuffle_does_not_loop();
    //             value
    //         }) {
    //             let successful: u128 = successful.convert();
    //             successful_list.insert(successful, iters_before_loop());
    //         }
    //     }
    //     let write_file = File::create("/tmp/output").unwrap();
    //     let mut writer = BufWriter::new(&write_file);
    //
    //     for success in successful_list {
    //         writeln!(writer, "Found successful: {:x?} - {:?}", success.0, success.1);
    //     }
    // }
    //
    // fn iters_before_loop() -> u32 {
    //     let numbered = 0x00112233_44556677_8899AABB_CCDDEEFF;
    //     let mut shuffled = shuffle(numbered);
    //     let mut count = 0;
    //     loop {
    //         // println!("{:>16x}", shuffled);
    //         if numbered == shuffled {
    //             break;
    //         }
    //         count += 1;
    //         shuffled = shuffle(shuffled);
    //     }
    //     count
    // }

    #[cfg(all(
        any(target_arch = "x86", target_arch = "x86_64"),
        target_feature = "ssse3",
        target_feature = "aes",
        not(miri)
    ))]
    #[test]
    fn test_shuffle_does_not_collide_with_aes() {
        let mut value: [u8; 16] = [0; 16];
        let zero_mask_enc = aesenc(0, 0);
        let zero_mask_dec = aesdec(0, 0);
        for index in 0..16 {
            value[index] = 1;
            let excluded_positions_enc: [u8; 16] = aesenc(value.convert(), zero_mask_enc).convert();
            let excluded_positions_dec: [u8; 16] = aesdec(value.convert(), zero_mask_dec).convert();
            let actual_location: [u8; 16] = shuffle(value.convert()).convert();
            for pos in 0..16 {
                if actual_location[pos] != 0 {
                    assert_eq!(
                        0, excluded_positions_enc[pos],
                        "Forward Overlap between {:?} and {:?} at {}",
                        excluded_positions_enc, actual_location, index
                    );
                    assert_eq!(
                        0, excluded_positions_dec[pos],
                        "Reverse Overlap between {:?} and {:?} at {}",
                        excluded_positions_dec, actual_location, index
                    );
                }
            }
            value[index] = 0;
        }
    }

    #[test]
    fn test_shuffle_contains_each_value() {
        let value: [u8; 16] = 0x00010203_04050607_08090A0B_0C0D0E0F_u128.convert();
        let shuffled: [u8; 16] = shuffle(value.convert()).convert();
        for index in 0..16_u8 {
            assert!(shuffled.contains(&index), "Value is missing {}", index);
        }
    }

    #[test]
    fn test_shuffle_moves_every_value() {
        let mut value: [u8; 16] = [0; 16];
        for index in 0..16 {
            value[index] = 1;
            let shuffled: [u8; 16] = shuffle(value.convert()).convert();
            assert_eq!(0, shuffled[index], "Value is not moved {}", index);
            value[index] = 0;
        }
    }

    #[test]
    fn test_shuffle_moves_high_bits() {
        assert!(
            shuffle(1) > (1_u128 << 80),
            "Low bits must be moved to other half {:?} -> {:?}",
            0,
            shuffle(1)
        );

        assert!(
            shuffle(1_u128 << 58) >= (1_u128 << 64),
            "High bits must be moved to other half {:?} -> {:?}",
            7,
            shuffle(1_u128 << 58)
        );
        assert!(
            shuffle(1_u128 << 58) < (1_u128 << 112),
            "High bits must not remain high {:?} -> {:?}",
            7,
            shuffle(1_u128 << 58)
        );
        assert!(
            shuffle(1_u128 << 64) < (1_u128 << 64),
            "Low bits must be moved to other half {:?} -> {:?}",
            8,
            shuffle(1_u128 << 64)
        );
        assert!(
            shuffle(1_u128 << 64) >= (1_u128 << 16),
            "Low bits must not remain low {:?} -> {:?}",
            8,
            shuffle(1_u128 << 64)
        );

        assert!(
            shuffle(1_u128 << 120) < (1_u128 << 50),
            "High bits must be moved to low half {:?} -> {:?}",
            15,
            shuffle(1_u128 << 120)
        );
    }

    #[cfg(all(
        any(target_arch = "x86", target_arch = "x86_64"),
        target_feature = "ssse3",
        not(miri)
    ))]
    #[test]
    fn test_shuffle_does_not_loop() {
        let numbered = 0x00112233_44556677_8899AABB_CCDDEEFF;
        let mut shuffled = shuffle(numbered);
        for count in 0..100 {
            // println!("{:>16x}", shuffled);
            assert_ne!(numbered, shuffled, "Equal after {} vs {:x}", count, shuffled);
            shuffled = shuffle(shuffled);
        }
    }

    #[test]
    fn test_add_length() {
        let mut enc = (u64::MAX as u128) << 64 | 50;
        add_in_length(&mut enc, u64::MAX);
        assert_eq!(enc >> 64, u64::MAX as u128);
        assert_eq!(enc as u64, 49);
    }
}