1 /*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 // It is not safe to #include any header file here unless it has been vetted for ODR safety:
9 // all symbols used must be file-scoped static or in an anonymous namespace. This applies
10 // to _all_ header files: C standard library, C++ standard library, Skia... everything.
11
12 #include <immintrin.h> // ODR safe
13 #include <stdint.h> // ODR safe
14
15 #if defined(__AVX2__)
16
17 namespace hsw {
18
convolve_vertically(const int16_t * filter,int filterLen,uint8_t * const * srcRows,int width,uint8_t * out,bool hasAlpha)19 void convolve_vertically(const int16_t* filter, int filterLen,
20 uint8_t* const* srcRows, int width,
21 uint8_t* out, bool hasAlpha) {
22 // It's simpler to work with the output array in terms of 4-byte pixels.
23 auto dst = (int*)out;
24
25 // Output up to eight pixels per iteration.
26 for (int x = 0; x < width; x += 8) {
27 // Accumulated result for 4 (non-adjacent) pairs of pixels,
28 // with each channel in signed 17.14 fixed point.
29 auto accum04 = _mm256_setzero_si256(),
30 accum15 = _mm256_setzero_si256(),
31 accum26 = _mm256_setzero_si256(),
32 accum37 = _mm256_setzero_si256();
33
34 // Convolve with the filter. (This inner loop is where we spend ~all our time.)
35 // While we can, we consume 2 filter coefficients and 2 rows of 8 pixels each at a time.
36 auto convolve_16_pixels = [&](__m256i interlaced_coeffs,
37 __m256i pixels_01234567, __m256i pixels_89ABCDEF) {
38 // Interlaced R0R8 G0G8 B0B8 A0A8 R1R9 G1G9... 32 8-bit values each.
39 auto _08194C5D = _mm256_unpacklo_epi8(pixels_01234567, pixels_89ABCDEF),
40 _2A3B6E7F = _mm256_unpackhi_epi8(pixels_01234567, pixels_89ABCDEF);
41
42 // Still interlaced R0R8 G0G8... as above, each channel expanded to 16-bit lanes.
43 auto _084C = _mm256_unpacklo_epi8(_08194C5D, _mm256_setzero_si256()),
44 _195D = _mm256_unpackhi_epi8(_08194C5D, _mm256_setzero_si256()),
45 _2A6E = _mm256_unpacklo_epi8(_2A3B6E7F, _mm256_setzero_si256()),
46 _3B7F = _mm256_unpackhi_epi8(_2A3B6E7F, _mm256_setzero_si256());
47
48 // accum0_R += R0*coeff0 + R8*coeff1, etc.
49 accum04 = _mm256_add_epi32(accum04, _mm256_madd_epi16(_084C, interlaced_coeffs));
50 accum15 = _mm256_add_epi32(accum15, _mm256_madd_epi16(_195D, interlaced_coeffs));
51 accum26 = _mm256_add_epi32(accum26, _mm256_madd_epi16(_2A6E, interlaced_coeffs));
52 accum37 = _mm256_add_epi32(accum37, _mm256_madd_epi16(_3B7F, interlaced_coeffs));
53 };
54
55 int i = 0;
56 for (; i < filterLen/2*2; i += 2) {
57 convolve_16_pixels(_mm256_set1_epi32(*(const int32_t*)(filter+i)),
58 _mm256_loadu_si256((const __m256i*)(srcRows[i+0] + x*4)),
59 _mm256_loadu_si256((const __m256i*)(srcRows[i+1] + x*4)));
60 }
61 if (i < filterLen) {
62 convolve_16_pixels(_mm256_set1_epi32(*(const int16_t*)(filter+i)),
63 _mm256_loadu_si256((const __m256i*)(srcRows[i] + x*4)),
64 _mm256_setzero_si256());
65 }
66
67 // Trim the fractional parts off the accumulators.
68 accum04 = _mm256_srai_epi32(accum04, 14);
69 accum15 = _mm256_srai_epi32(accum15, 14);
70 accum26 = _mm256_srai_epi32(accum26, 14);
71 accum37 = _mm256_srai_epi32(accum37, 14);
72
73 // Pack back down to 8-bit channels.
74 auto pixels = _mm256_packus_epi16(_mm256_packs_epi32(accum04, accum15),
75 _mm256_packs_epi32(accum26, accum37));
76
77 if (hasAlpha) {
78 // Clamp alpha to the max of r,g,b to make sure we stay premultiplied.
79 __m256i max_rg = _mm256_max_epu8(pixels, _mm256_srli_epi32(pixels, 8)),
80 max_rgb = _mm256_max_epu8(max_rg, _mm256_srli_epi32(pixels, 16));
81 pixels = _mm256_max_epu8(pixels, _mm256_slli_epi32(max_rgb, 24));
82 } else {
83 // Force opaque.
84 pixels = _mm256_or_si256(pixels, _mm256_set1_epi32(0xff000000));
85 }
86
87 // Normal path to store 8 pixels.
88 if (x + 8 <= width) {
89 _mm256_storeu_si256((__m256i*)dst, pixels);
90 dst += 8;
91 continue;
92 }
93
94 // Store one pixel at a time on the last iteration.
95 for (int i = x; i < width; i++) {
96 *dst++ = _mm_cvtsi128_si32(_mm256_castsi256_si128(pixels));
97 pixels = _mm256_permutevar8x32_epi32(pixels, _mm256_setr_epi32(1,2,3,4,5,6,7,0));
98 }
99 }
100 }
101
102 }
103
104 namespace SkOpts {
105 // See SkOpts.h, writing SkConvolutionFilter1D::ConvolutionFixed as the underlying type.
106 extern void (*convolve_vertically)(const int16_t* filter, int filterLen,
107 uint8_t* const* srcRows, int width,
108 uint8_t* out, bool hasAlpha);
Init_hsw()109 void Init_hsw() {
110 convolve_vertically = hsw::convolve_vertically;
111 }
112 }
113
114 #else // defined(__AVX2__) is not true...
115
Init_hsw()116 namespace SkOpts { void Init_hsw() {} }
117
118 #endif
119