simd_adler32/imp/
sse2.rs

1use super::Adler32Imp;
2
3/// Resolves update implementation if CPU supports sse2 instructions.
4pub fn get_imp() -> Option<Adler32Imp> {
5  get_imp_inner()
6}
7
8#[inline]
9#[cfg(all(feature = "std", any(target_arch = "x86", target_arch = "x86_64")))]
10fn get_imp_inner() -> Option<Adler32Imp> {
11  if std::is_x86_feature_detected!("sse2") {
12    Some(imp::update)
13  } else {
14    None
15  }
16}
17
18#[inline]
19#[cfg(all(
20  target_feature = "sse2",
21  not(all(feature = "std", any(target_arch = "x86", target_arch = "x86_64")))
22))]
23fn get_imp_inner() -> Option<Adler32Imp> {
24  Some(imp::update)
25}
26
27#[inline]
28#[cfg(all(
29  not(target_feature = "sse2"),
30  not(all(feature = "std", any(target_arch = "x86", target_arch = "x86_64")))
31))]
32fn get_imp_inner() -> Option<Adler32Imp> {
33  None
34}
35
36#[cfg(all(
37  any(target_arch = "x86", target_arch = "x86_64"),
38  any(feature = "std", target_feature = "sse2")
39))]
40mod imp {
41  const MOD: u32 = 65521;
42  const NMAX: usize = 5552;
43  const BLOCK_SIZE: usize = 32;
44  const CHUNK_SIZE: usize = NMAX / BLOCK_SIZE * BLOCK_SIZE;
45
46  #[cfg(target_arch = "x86")]
47  use core::arch::x86::*;
48  #[cfg(target_arch = "x86_64")]
49  use core::arch::x86_64::*;
50
51  pub fn update(a: u16, b: u16, data: &[u8]) -> (u16, u16) {
52    unsafe { update_imp(a, b, data) }
53  }
54
55  #[inline]
56  #[target_feature(enable = "sse2")]
57  unsafe fn update_imp(a: u16, b: u16, data: &[u8]) -> (u16, u16) {
58    let mut a = a as u32;
59    let mut b = b as u32;
60
61    let chunks = data.chunks_exact(CHUNK_SIZE);
62    let remainder = chunks.remainder();
63    for chunk in chunks {
64      update_chunk_block(&mut a, &mut b, chunk);
65    }
66
67    update_block(&mut a, &mut b, remainder);
68
69    (a as u16, b as u16)
70  }
71
72  unsafe fn update_chunk_block(a: &mut u32, b: &mut u32, chunk: &[u8]) {
73    debug_assert_eq!(
74      chunk.len(),
75      CHUNK_SIZE,
76      "Unexpected chunk size (expected {}, got {})",
77      CHUNK_SIZE,
78      chunk.len()
79    );
80
81    reduce_add_blocks(a, b, chunk);
82
83    *a %= MOD;
84    *b %= MOD;
85  }
86
87  unsafe fn update_block(a: &mut u32, b: &mut u32, chunk: &[u8]) {
88    debug_assert!(
89      chunk.len() <= CHUNK_SIZE,
90      "Unexpected chunk size (expected <= {}, got {})",
91      CHUNK_SIZE,
92      chunk.len()
93    );
94
95    for byte in reduce_add_blocks(a, b, chunk) {
96      *a += *byte as u32;
97      *b += *a;
98    }
99
100    *a %= MOD;
101    *b %= MOD;
102  }
103
104  #[inline(always)]
105  unsafe fn reduce_add_blocks<'a>(a: &mut u32, b: &mut u32, chunk: &'a [u8]) -> &'a [u8] {
106    if chunk.len() < BLOCK_SIZE {
107      return chunk;
108    }
109
110    let blocks = chunk.chunks_exact(BLOCK_SIZE);
111    let blocks_remainder = blocks.remainder();
112
113    let zero_v = _mm_setzero_si128();
114    let weight_hi_v = get_weight_hi();
115    let weight_lo_v = get_weight_lo();
116
117    let mut p_v = _mm_set_epi32(0, 0, 0, (*a * blocks.len() as u32) as _);
118    let mut a_v = _mm_setzero_si128();
119    let mut b_v = _mm_set_epi32(0, 0, 0, *b as _);
120
121    for block in blocks {
122      let block_ptr = block.as_ptr() as *const _;
123      let left_v = _mm_loadu_si128(block_ptr);
124      let right_v = _mm_loadu_si128(block_ptr.add(1));
125
126      p_v = _mm_add_epi32(p_v, a_v);
127
128      a_v = _mm_add_epi32(a_v, _mm_sad_epu8(left_v, zero_v));
129      let mad = maddubs(left_v, weight_hi_v);
130      b_v = _mm_add_epi32(b_v, mad);
131
132      a_v = _mm_add_epi32(a_v, _mm_sad_epu8(right_v, zero_v));
133      let mad = maddubs(right_v, weight_lo_v);
134      b_v = _mm_add_epi32(b_v, mad);
135    }
136
137    b_v = _mm_add_epi32(b_v, _mm_slli_epi32(p_v, 5));
138
139    *a += reduce_add(a_v);
140    *b = reduce_add(b_v);
141
142    blocks_remainder
143  }
144
145  #[inline(always)]
146  unsafe fn maddubs(a: __m128i, b: __m128i) -> __m128i {
147    let a_lo = _mm_unpacklo_epi8(a, _mm_setzero_si128());
148    let a_hi = _mm_unpackhi_epi8(a, _mm_setzero_si128());
149
150    let b_lo = _mm_unpacklo_epi8(b, _mm_setzero_si128());
151    let b_hi = _mm_unpackhi_epi8(b, _mm_setzero_si128());
152
153    let lo = _mm_madd_epi16(a_lo, b_lo);
154    let hi = _mm_madd_epi16(a_hi, b_hi);
155
156    _mm_add_epi32(lo, hi)
157  }
158
159  #[inline(always)]
160  unsafe fn reduce_add(v: __m128i) -> u32 {
161    let hi = _mm_unpackhi_epi64(v, v);
162    let sum = _mm_add_epi32(hi, v);
163    let hi = _mm_shuffle_epi32(sum, crate::imp::_MM_SHUFFLE(2, 3, 0, 1));
164
165    let sum = _mm_add_epi32(sum, hi);
166
167    _mm_cvtsi128_si32(sum) as _
168  }
169
170  #[inline(always)]
171  unsafe fn get_weight_lo() -> __m128i {
172    _mm_set_epi8(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
173  }
174
175  #[inline(always)]
176  unsafe fn get_weight_hi() -> __m128i {
177    _mm_set_epi8(
178      17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
179    )
180  }
181}
182
183#[cfg(test)]
184mod tests {
185  use rand::{Rng, SeedableRng, rngs::SmallRng};
186
187  #[test]
188  fn zeroes() {
189    assert_sum_eq(&[]);
190    assert_sum_eq(&[0]);
191    assert_sum_eq(&[0, 0]);
192    assert_sum_eq(&[0; 100]);
193    assert_sum_eq(&[0; 1024]);
194    assert_sum_eq(&[0; 1024 - 5]);
195    #[cfg(not(miri))]
196    assert_sum_eq(&[0; 1024 * 1024]);
197  }
198
199  #[test]
200  fn ones() {
201    assert_sum_eq(&[]);
202    assert_sum_eq(&[1]);
203    assert_sum_eq(&[1, 1]);
204    assert_sum_eq(&[1; 100]);
205    assert_sum_eq(&[1; 1024]);
206    assert_sum_eq(&[1; 1024 - 5]); // non-power-of-2 to test remainder handling
207    #[cfg(not(miri))]
208    assert_sum_eq(&[1; 1024 * 1024]);
209  }
210
211  #[test]
212  fn random() {
213    if super::get_imp().is_none() { return; } // don't do any work if we're not on this target
214    let mut random = [0; 1024 * 10];
215    SmallRng::from_entropy().fill(&mut random[..]);
216
217    assert_sum_eq(&random[..1]);
218    assert_sum_eq(&random[..100]);
219    assert_sum_eq(&random[..1024]);
220    assert_sum_eq(&random[..1024 - 5]); // non-power-of-2 to test remainder handling
221    assert_sum_eq(&random[..1024 * 10]);
222  }
223
224  /// Example calculation from https://en.wikipedia.org/wiki/Adler-32.
225  #[test]
226  fn wiki() {
227    assert_sum_eq(b"Wikipedia");
228  }
229
230  fn assert_sum_eq(data: &[u8]) {
231    if let Some(update) = super::get_imp() {
232      let (a, b) = update(1, 0, data);
233      let left = u32::from(b) << 16 | u32::from(a);
234      let right = adler::adler32_slice(data);
235
236      assert_eq!(left, right, "len({})", data.len());
237    }
238  }
239}
simd_adler32/imp/sse2.rs

simd_adler32/imp/
sse2.rs
