PAM-less i3lock-color fork
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/*
* vim:ts=4:sw=4:expandtab
*
* © 2016 Sebastian Frysztak
*
* See LICENSE for licensing information
*
*/
#include "blur.h"
#include <math.h>
#include <xmmintrin.h>
#define ALIGN16 __attribute__((aligned(16)))
#define KERNEL_SIZE 7
#define HALF_KERNEL KERNEL_SIZE / 2
void blur_impl_sse2(uint32_t *src, uint32_t *dst, int width, int height, float sigma) {
// prepare kernel
float kernel[KERNEL_SIZE];
float coeff = 1.0 / sqrtf(2 * M_PI * sigma * sigma), sum = 0;
for (int i = 0; i < KERNEL_SIZE; i++) {
float x = HALF_KERNEL - i;
kernel[i] = coeff * expf(-x * x / (2.0 * sigma * sigma));
sum += kernel[i];
}
// normalize kernel
for (int i = 0; i < KERNEL_SIZE; i++)
kernel[i] /= sum;
// horizontal pass includes image transposition:
// instead of writing pixel src[x] to dst[x],
// we write it to transposed location.
// (to be exact: dst[height * current_column + current_row])
blur_impl_horizontal_pass_sse2(src, dst, kernel, width, height);
blur_impl_horizontal_pass_sse2(dst, src, kernel, height, width);
}
void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, float *kernel, int width, int height) {
for (int row = 0; row < height; row++) {
// remember first and last pixel in a row
// (used to handle borders)
uint32_t firstPixel = *src;
uint32_t lastPixel = *(src + width - 1);
for (int column = 0; column < width; column++, src++) {
__m128i rgbaIn1, rgbaIn2;
// handle borders
int leftBorder = column < HALF_KERNEL;
int rightBorder = column + HALF_KERNEL >= width;
if (leftBorder || rightBorder) {
uint32_t rgbaIn[KERNEL_SIZE] ALIGN16;
int i = 0;
if (leftBorder) {
// for kernel size 7x7 and column == 0, we have:
// x x x P0 P1 P2 P3
// first loop fills x's with P0, second one loads P{0..3}
for (; i < HALF_KERNEL - column; i++)
rgbaIn[i] = firstPixel;
for (; i < KERNEL_SIZE; i++)
rgbaIn[i] = *(src + i - HALF_KERNEL);
} else {
for (; width < column; i++)
rgbaIn[i] = *(src - i - HALF_KERNEL);
for (; i < KERNEL_SIZE; i++)
rgbaIn[i] = lastPixel;
}
rgbaIn1 = _mm_load_si128((__m128i *)(rgbaIn));
rgbaIn2 = _mm_load_si128((__m128i *)(rgbaIn + 4));
} else {
rgbaIn1 = _mm_loadu_si128((__m128i *)(src - 3));
rgbaIn2 = _mm_loadu_si128((__m128i *)(src + 1));
}
// unpack each pixel, convert to float,
// multiply by corresponding kernel value
// and add to accumulator
__m128i tmp;
__m128i zero = _mm_setzero_si128();
__m128 rgba_ps;
__m128 acc = _mm_setzero_ps();
int counter = 0;
tmp = _mm_unpacklo_epi8(rgbaIn1, zero);
rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
rgba_ps = _mm_cvtepi32_ps(_mm_unpackhi_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
tmp = _mm_unpackhi_epi8(rgbaIn1, zero);
rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
rgba_ps = _mm_cvtepi32_ps(_mm_unpackhi_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
tmp = _mm_unpacklo_epi8(rgbaIn2, zero);
rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
rgba_ps = _mm_cvtepi32_ps(_mm_unpackhi_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
tmp = _mm_unpackhi_epi8(rgbaIn2, zero);
rgba_ps = _mm_cvtepi32_ps(_mm_unpacklo_epi16(tmp, zero));
acc = _mm_add_ps(acc, _mm_mul_ps(rgba_ps, _mm_set1_ps(kernel[counter++])));
__m128i rgbaOut = _mm_cvtps_epi32(acc);
rgbaOut = _mm_packs_epi32(rgbaOut, zero);
rgbaOut = _mm_packus_epi16(rgbaOut, zero);
*(dst + height * column + row) = _mm_cvtsi128_si32(rgbaOut);
}
}
}