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117 lines
4.6 KiB
117 lines
4.6 KiB
8 years ago
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/*
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* vim:ts=4:sw=4:expandtab
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*
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* © 2016 Sebastian Frysztak
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*
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* See LICENSE for licensing information
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*
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*/
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#include "blur.h"
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#include <math.h>
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#include <xmmintrin.h>
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#define ALIGN16 __attribute__((aligned(16)))
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#define KERNEL_SIZE 7
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#define HALF_KERNEL KERNEL_SIZE / 2
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void blur_impl_sse2(uint32_t *src, uint32_t *dst, int width, int height, float sigma) {
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// prepare kernel
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float kernel[KERNEL_SIZE];
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float coeff = 1.0 / sqrtf(2 * M_PI * sigma * sigma), sum = 0;
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for (int i = 0; i < KERNEL_SIZE; i++) {
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float x = HALF_KERNEL - i;
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kernel[i] = coeff * expf(-x * x / (2.0 * sigma * sigma));
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sum += kernel[i];
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}
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// normalize kernel
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for (int i = 0; i < KERNEL_SIZE; i++)
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kernel[i] /= sum;
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// horizontal pass includes image transposition:
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// instead of writing pixel src[x] to dst[x],
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// we write it to transposed location.
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// (to be exact: dst[height * current_column + current_row])
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blur_impl_horizontal_pass_sse2(src, dst, kernel, width, height);
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blur_impl_horizontal_pass_sse2(dst, src, kernel, height, width);
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}
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void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, float *kernel, int width, int height) {
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for (int row = 0; row < height; row++) {
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// remember first and last pixel in a row
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// (used to handle borders)
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uint32_t firstPixel = *src;
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uint32_t lastPixel = *(src + width - 1);
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for (int column = 0; column < width; column++, src++) {
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__m128i rgbaIn1, rgbaIn2;
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// handle borders
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int leftBorder = column < HALF_KERNEL;
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int rightBorder = column + HALF_KERNEL >= width;
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if (leftBorder || rightBorder) {
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uint32_t rgbaIn[KERNEL_SIZE] ALIGN16;
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int i = 0;
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if (leftBorder) {
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// for kernel size 7x7 and column == 0, we have:
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// x x x P0 P1 P2 P3
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// first loop fills x's with P0, second one loads P{0..3}
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for (; i < HALF_KERNEL - column; i++)
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rgbaIn[i] = firstPixel;
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for (; i < KERNEL_SIZE; i++)
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rgbaIn[i] = *(src + i - HALF_KERNEL);
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} else {
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for (; width < column; i++)
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rgbaIn[i] = *(src - i - HALF_KERNEL);
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for (; i < KERNEL_SIZE; i++)
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rgbaIn[i] = lastPixel;
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}
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rgbaIn1 = _mm_load_si128((__m128i *)(rgbaIn));
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rgbaIn2 = _mm_load_si128((__m128i *)(rgbaIn + 4));
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} else {
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rgbaIn1 = _mm_loadu_si128((__m128i *)(src - 3));
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rgbaIn2 = _mm_loadu_si128((__m128i *)(src + 1));
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}
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// unpack each pixel, convert to float,
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// multiply by corresponding kernel value
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// and add to accumulator
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__m128i tmp;
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__m128i zero = _mm_setzero_si128();
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__m128 rgba_ps;
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__m128 acc = _mm_setzero_ps();
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int counter = 0;
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tmp = _mm_unpacklo_epi8(rgbaIn1, zero);
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rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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rgba_ps = _mm_cvtepi32_ps(_mm_unpackhi_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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tmp = _mm_unpackhi_epi8(rgbaIn1, zero);
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rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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rgba_ps = _mm_cvtepi32_ps(_mm_unpackhi_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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tmp = _mm_unpacklo_epi8(rgbaIn2, zero);
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rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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rgba_ps = _mm_cvtepi32_ps(_mm_unpackhi_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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tmp = _mm_unpackhi_epi8(rgbaIn2, zero);
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rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
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acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
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__m128i rgbaOut = _mm_cvtps_epi32(acc);
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rgbaOut = _mm_packs_epi32(rgbaOut, zero);
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rgbaOut = _mm_packus_epi16(rgbaOut, zero);
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*(dst + height * column + row) = _mm_cvtsi128_si32(rgbaOut);
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}
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}
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}
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