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-rw-r--r--contrib/intel/filter_sse2_intrinsics.c379
1 files changed, 0 insertions, 379 deletions
diff --git a/contrib/intel/filter_sse2_intrinsics.c b/contrib/intel/filter_sse2_intrinsics.c
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--- a/contrib/intel/filter_sse2_intrinsics.c
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-
-/* filter_sse2_intrinsics.c - SSE2 optimized filter functions
- *
- * Copyright (c) 2016 Google, Inc.
- * Written by Mike Klein and Matt Sarett
- * Derived from arm/filter_neon_intrinsics.c, which was
- * Copyright (c) 2014,2016 Glenn Randers-Pehrson
- *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
- */
-
-#include "../../pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-
-#if PNG_INTEL_SSE_IMPLEMENTATION > 0
-
-#include <immintrin.h>
-
-/* Functions in this file look at most 3 pixels (a,b,c) to predict the 4th (d).
- * They're positioned like this:
- * prev: c b
- * row: a d
- * The Sub filter predicts d=a, Avg d=(a+b)/2, and Paeth predicts d to be
- * whichever of a, b, or c is closest to p=a+b-c.
- */
-
-static __m128i load4(const void* p) {
- return _mm_cvtsi32_si128(*(const int*)p);
-}
-
-static void store4(void* p, __m128i v) {
- *(int*)p = _mm_cvtsi128_si32(v);
-}
-
-static __m128i load3(const void* p) {
- /* We'll load 2 bytes, then 1 byte,
- * then mask them together, and finally load into SSE.
- */
- const png_uint_16* p01 = p;
- const png_byte* p2 = (const png_byte*)(p01+1);
-
- png_uint_32 v012 = (png_uint_32)(*p01)
- | (png_uint_32)(*p2) << 16;
- return load4(&v012);
-}
-
-static void store3(void* p, __m128i v) {
- /* We'll pull from SSE as a 32-bit int, then write
- * its bottom two bytes, then its third byte.
- */
- png_uint_32 v012;
- store4(&v012, v);
-
- png_uint_16* p01 = p;
- png_byte* p2 = (png_byte*)(p01+1);
- *p01 = v012;
- *p2 = v012 >> 16;
-}
-
-void png_read_filter_row_sub3_sse2(png_row_infop row_info, png_bytep row,
- png_const_bytep prev)
-{
- /* The Sub filter predicts each pixel as the previous pixel, a.
- * There is no pixel to the left of the first pixel. It's encoded directly.
- * That works with our main loop if we just say that left pixel was zero.
- */
- png_debug(1, "in png_read_filter_row_sub3_sse2");
- __m128i a, d = _mm_setzero_si128();
-
- int rb = row_info->rowbytes;
- while (rb >= 4) {
- a = d; d = load4(row);
- d = _mm_add_epi8(d, a);
- store3(row, d);
-
- row += 3;
- rb -= 3;
- }
- if (rb > 0) {
- a = d; d = load3(row);
- d = _mm_add_epi8(d, a);
- store3(row, d);
-
- row += 3;
- rb -= 3;
- }
-}
-
-void png_read_filter_row_sub4_sse2(png_row_infop row_info, png_bytep row,
- png_const_bytep prev)
-{
- /* The Sub filter predicts each pixel as the previous pixel, a.
- * There is no pixel to the left of the first pixel. It's encoded directly.
- * That works with our main loop if we just say that left pixel was zero.
- */
- png_debug(1, "in png_read_filter_row_sub4_sse2");
- __m128i a, d = _mm_setzero_si128();
-
- int rb = row_info->rowbytes;
- while (rb > 0) {
- a = d; d = load4(row);
- d = _mm_add_epi8(d, a);
- store4(row, d);
-
- row += 4;
- rb -= 4;
- }
-}
-
-void png_read_filter_row_avg3_sse2(png_row_infop row_info, png_bytep row,
- png_const_bytep prev)
-{
- /* The Avg filter predicts each pixel as the (truncated) average of a and b.
- * There's no pixel to the left of the first pixel. Luckily, it's
- * predicted to be half of the pixel above it. So again, this works
- * perfectly with our loop if we make sure a starts at zero.
- */
- png_debug(1, "in png_read_filter_row_avg3_sse2");
- const __m128i zero = _mm_setzero_si128();
- __m128i b;
- __m128i a, d = zero;
-
- int rb = row_info->rowbytes;
- while (rb >= 4) {
- b = load4(prev);
- a = d; d = load4(row );
-
- /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
- __m128i avg = _mm_avg_epu8(a,b);
- /* ...but we can fix it up by subtracting off 1 if it rounded up. */
- avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
- _mm_set1_epi8(1)));
- d = _mm_add_epi8(d, avg);
- store3(row, d);
-
- prev += 3;
- row += 3;
- rb -= 3;
- }
- if (rb > 0) {
- b = load3(prev);
- a = d; d = load3(row );
-
- /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
- __m128i avg = _mm_avg_epu8(a,b);
- /* ...but we can fix it up by subtracting off 1 if it rounded up. */
- avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
- _mm_set1_epi8(1)));
-
- d = _mm_add_epi8(d, avg);
- store3(row, d);
-
- prev += 3;
- row += 3;
- rb -= 3;
- }
-}
-
-void png_read_filter_row_avg4_sse2(png_row_infop row_info, png_bytep row,
- png_const_bytep prev)
-{
- /* The Avg filter predicts each pixel as the (truncated) average of a and b.
- * There's no pixel to the left of the first pixel. Luckily, it's
- * predicted to be half of the pixel above it. So again, this works
- * perfectly with our loop if we make sure a starts at zero.
- */
- png_debug(1, "in png_read_filter_row_avg4_sse2");
- const __m128i zero = _mm_setzero_si128();
- __m128i b;
- __m128i a, d = zero;
-
- int rb = row_info->rowbytes;
- while (rb > 0) {
- b = load4(prev);
- a = d; d = load4(row );
-
- /* PNG requires a truncating average, so we can't just use _mm_avg_epu8 */
- __m128i avg = _mm_avg_epu8(a,b);
- /* ...but we can fix it up by subtracting off 1 if it rounded up. */
- avg = _mm_sub_epi8(avg, _mm_and_si128(_mm_xor_si128(a,b),
- _mm_set1_epi8(1)));
-
- d = _mm_add_epi8(d, avg);
- store4(row, d);
-
- prev += 4;
- row += 4;
- rb -= 4;
- }
-}
-
-/* Returns |x| for 16-bit lanes. */
-static __m128i abs_i16(__m128i x) {
-#if PNG_INTEL_SSE_IMPLEMENTATION >= 2
- return _mm_abs_epi16(x);
-#else
- /* Read this all as, return x<0 ? -x : x.
- * To negate two's complement, you flip all the bits then add 1.
- */
- __m128i is_negative = _mm_cmplt_epi16(x, _mm_setzero_si128());
-
- /* Flip negative lanes. */
- x = _mm_xor_si128(x, is_negative);
-
- /* +1 to negative lanes, else +0. */
- x = _mm_sub_epi16(x, is_negative);
- return x;
-#endif
-}
-
-/* Bytewise c ? t : e. */
-static __m128i if_then_else(__m128i c, __m128i t, __m128i e) {
-#if PNG_INTEL_SSE_IMPLEMENTATION >= 3
- return _mm_blendv_epi8(e,t,c);
-#else
- return _mm_or_si128(_mm_and_si128(c, t), _mm_andnot_si128(c, e));
-#endif
-}
-
-void png_read_filter_row_paeth3_sse2(png_row_infop row_info, png_bytep row,
- png_const_bytep prev)
-{
- /* Paeth tries to predict pixel d using the pixel to the left of it, a,
- * and two pixels from the previous row, b and c:
- * prev: c b
- * row: a d
- * The Paeth function predicts d to be whichever of a, b, or c is nearest to
- * p=a+b-c.
- *
- * The first pixel has no left context, and so uses an Up filter, p = b.
- * This works naturally with our main loop's p = a+b-c if we force a and c
- * to zero.
- * Here we zero b and d, which become c and a respectively at the start of
- * the loop.
- */
- png_debug(1, "in png_read_filter_row_paeth3_sse2");
- const __m128i zero = _mm_setzero_si128();
- __m128i c, b = zero,
- a, d = zero;
-
- int rb = row_info->rowbytes;
- while (rb >= 4) {
- /* It's easiest to do this math (particularly, deal with pc) with 16-bit
- * intermediates.
- */
- c = b; b = _mm_unpacklo_epi8(load4(prev), zero);
- a = d; d = _mm_unpacklo_epi8(load4(row ), zero);
-
- /* (p-a) == (a+b-c - a) == (b-c) */
- __m128i pa = _mm_sub_epi16(b,c);
-
- /* (p-b) == (a+b-c - b) == (a-c) */
- __m128i pb = _mm_sub_epi16(a,c);
-
- /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
- __m128i pc = _mm_add_epi16(pa,pb);
-
- pa = abs_i16(pa); /* |p-a| */
- pb = abs_i16(pb); /* |p-b| */
- pc = abs_i16(pc); /* |p-c| */
-
- __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
- /* Paeth breaks ties favoring a over b over c. */
- __m128i nearest = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
- if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
- c));
-
- /* Note `_epi8`: we need addition to wrap modulo 255. */
- d = _mm_add_epi8(d, nearest);
- store3(row, _mm_packus_epi16(d,d));
-
- prev += 3;
- row += 3;
- rb -= 3;
- }
- if (rb > 0) {
- /* It's easiest to do this math (particularly, deal with pc) with 16-bit
- * intermediates.
- */
- c = b; b = _mm_unpacklo_epi8(load3(prev), zero);
- a = d; d = _mm_unpacklo_epi8(load3(row ), zero);
-
- /* (p-a) == (a+b-c - a) == (b-c) */
- __m128i pa = _mm_sub_epi16(b,c);
-
- /* (p-b) == (a+b-c - b) == (a-c) */
- __m128i pb = _mm_sub_epi16(a,c);
-
- /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
- __m128i pc = _mm_add_epi16(pa,pb);
-
- pa = abs_i16(pa); /* |p-a| */
- pb = abs_i16(pb); /* |p-b| */
- pc = abs_i16(pc); /* |p-c| */
-
- __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
- /* Paeth breaks ties favoring a over b over c. */
- __m128i nearest = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
- if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
- c));
-
- /* Note `_epi8`: we need addition to wrap modulo 255. */
- d = _mm_add_epi8(d, nearest);
- store3(row, _mm_packus_epi16(d,d));
-
- prev += 3;
- row += 3;
- rb -= 3;
- }
-}
-
-void png_read_filter_row_paeth4_sse2(png_row_infop row_info, png_bytep row,
- png_const_bytep prev)
-{
- /* Paeth tries to predict pixel d using the pixel to the left of it, a,
- * and two pixels from the previous row, b and c:
- * prev: c b
- * row: a d
- * The Paeth function predicts d to be whichever of a, b, or c is nearest to
- * p=a+b-c.
- *
- * The first pixel has no left context, and so uses an Up filter, p = b.
- * This works naturally with our main loop's p = a+b-c if we force a and c
- * to zero.
- * Here we zero b and d, which become c and a respectively at the start of
- * the loop.
- */
- png_debug(1, "in png_read_filter_row_paeth4_sse2");
- const __m128i zero = _mm_setzero_si128();
- __m128i c, b = zero,
- a, d = zero;
-
- int rb = row_info->rowbytes;
- while (rb > 0) {
- /* It's easiest to do this math (particularly, deal with pc) with 16-bit
- * intermediates.
- */
- c = b; b = _mm_unpacklo_epi8(load4(prev), zero);
- a = d; d = _mm_unpacklo_epi8(load4(row ), zero);
-
- /* (p-a) == (a+b-c - a) == (b-c) */
- __m128i pa = _mm_sub_epi16(b,c);
-
- /* (p-b) == (a+b-c - b) == (a-c) */
- __m128i pb = _mm_sub_epi16(a,c);
-
- /* (p-c) == (a+b-c - c) == (a+b-c-c) == (b-c)+(a-c) */
- __m128i pc = _mm_add_epi16(pa,pb);
-
- pa = abs_i16(pa); /* |p-a| */
- pb = abs_i16(pb); /* |p-b| */
- pc = abs_i16(pc); /* |p-c| */
-
- __m128i smallest = _mm_min_epi16(pc, _mm_min_epi16(pa, pb));
-
- /* Paeth breaks ties favoring a over b over c. */
- __m128i nearest = if_then_else(_mm_cmpeq_epi16(smallest, pa), a,
- if_then_else(_mm_cmpeq_epi16(smallest, pb), b,
- c));
-
- /* Note `_epi8`: we need addition to wrap modulo 255. */
- d = _mm_add_epi8(d, nearest);
- store4(row, _mm_packus_epi16(d,d));
-
- prev += 4;
- row += 4;
- rb -= 4;
- }
-}
-
-#endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
-#endif /* READ */
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