tesseract  5.0.0
dotproductavx.cpp
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1 // File: dotproductavx.cpp
3 // Description: Architecture-specific dot-product function.
4 // Author: Ray Smith
5 //
6 // (C) Copyright 2015, Google Inc.
7 // Licensed under the Apache License, Version 2.0 (the "License");
8 // you may not use this file except in compliance with the License.
9 // You may obtain a copy of the License at
10 // http://www.apache.org/licenses/LICENSE-2.0
11 // Unless required by applicable law or agreed to in writing, software
12 // distributed under the License is distributed on an "AS IS" BASIS,
13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 // See the License for the specific language governing permissions and
15 // limitations under the License.
17 
18 #if !defined(__AVX__)
19 # if defined(__i686__) || defined(__x86_64__)
20 # error Implementation only for AVX capable architectures
21 # endif
22 #else
23 
24 # include <immintrin.h>
25 # include <cstdint>
26 # include "dotproduct.h"
27 
28 namespace tesseract {
29 
30 // Computes and returns the dot product of the n-vectors u and v.
31 // Uses Intel AVX intrinsics to access the SIMD instruction set.
32 #if defined(FAST_FLOAT)
33 float DotProductAVX(const float *u, const float *v, int n) {
34  const unsigned quot = n / 8;
35  const unsigned rem = n % 8;
36  __m256 t0 = _mm256_setzero_ps();
37  for (unsigned k = 0; k < quot; k++) {
38  __m256 f0 = _mm256_loadu_ps(u);
39  __m256 f1 = _mm256_loadu_ps(v);
40  f0 = _mm256_mul_ps(f0, f1);
41  t0 = _mm256_add_ps(t0, f0);
42  u += 8;
43  v += 8;
44  }
45  alignas(32) float tmp[8];
46  _mm256_store_ps(tmp, t0);
47  float result = tmp[0] + tmp[1] + tmp[2] + tmp[3] + tmp[4] + tmp[5] + tmp[6] + tmp[7];
48  for (unsigned k = 0; k < rem; k++) {
49  result += *u++ * *v++;
50  }
51  return result;
52 }
53 #else
54 double DotProductAVX(const double *u, const double *v, int n) {
55  const unsigned quot = n / 8;
56  const unsigned rem = n % 8;
57  __m256d t0 = _mm256_setzero_pd();
58  __m256d t1 = _mm256_setzero_pd();
59  for (unsigned k = 0; k < quot; k++) {
60  __m256d f0 = _mm256_loadu_pd(u);
61  __m256d f1 = _mm256_loadu_pd(v);
62  f0 = _mm256_mul_pd(f0, f1);
63  t0 = _mm256_add_pd(t0, f0);
64  u += 4;
65  v += 4;
66  __m256d f2 = _mm256_loadu_pd(u);
67  __m256d f3 = _mm256_loadu_pd(v);
68  f2 = _mm256_mul_pd(f2, f3);
69  t1 = _mm256_add_pd(t1, f2);
70  u += 4;
71  v += 4;
72  }
73  t0 = _mm256_hadd_pd(t0, t1);
74  alignas(32) double tmp[4];
75  _mm256_store_pd(tmp, t0);
76  double result = tmp[0] + tmp[1] + tmp[2] + tmp[3];
77  for (unsigned k = 0; k < rem; k++) {
78  result += *u++ * *v++;
79  }
80  return result;
81 }
82 #endif
83 
84 } // namespace tesseract.
85 
86 #endif
TFloat DotProductAVX(const TFloat *u, const TFloat *v, int n)