PolytreeDE/i3lock-color
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Clean up a bit.

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Sebastian Frysztak 2016-11-11 18:45:20 +01:00
parent 020af692e6
commit 6029c8e0b5
2 changed files with 24 additions and 20 deletions
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2
blur.h
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@ -8,7 +8,7 @@ void blur_image_surface (cairo_surface_t *surface, int radius);
void blur_impl_naive(uint32_t* src, uint32_t* dst, int width, int height, int src_stride, int dst_stride, int radius);
void blur_impl_sse2(uint32_t* src, uint32_t* dst, int width, int height, float sigma);
void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, float *kernel, int width, int height);
void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, int width, int height);
#endif

42
blur_simd.c
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@ -13,6 +13,7 @@
#define ALIGN16 __attribute__((aligned(16)))
#define KERNEL_SIZE 7
#define SIGMA_AV 2
#define HALF_KERNEL KERNEL_SIZE / 2
// number of xmm registers needed to store
@ -20,29 +21,31 @@
#define REGISTERS_CNT (KERNEL_SIZE + 4/2) / 4
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;
// according to a paper by Peter Kovesi [1], box filter of width w, equals to Gaussian blur of following sigma:
// σ_av = sqrt((w*w-1)/12)
// for our 7x7 filter we have σ_av = 2.0.
// applying the same Gaussian filter n times results in σ_n = sqrt(n*σ_av*σ_av) [2]
// after some trivial math, we arrive at n = ((σ_d)/(σ_av))^2
// since it's a box blur filter, n >= 3
//
// [1]: http://www.peterkovesi.com/papers/FastGaussianSmoothing.pdf
// [2]: https://en.wikipedia.org/wiki/Gaussian_blur#Mathematics
int n = lrintf((sigma*sigma)/(SIGMA_AV*SIGMA_AV));
if (n < 3) n = 3;
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];
for (int i = 0; i < n; i++)
{
// 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, width, height);
blur_impl_horizontal_pass_sse2(dst, src, height, width);
}
// 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) {
void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, int width, int height) {
for (int row = 0; row < height; row++) {
for (int column = 0; column < width; column++, src++) {
__m128i rgbaIn[REGISTERS_CNT];
@ -91,6 +94,7 @@ void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, float *kernel,
acc = _mm_add_epi32(_mm_unpacklo_epi16(acc, zero),
_mm_unpackhi_epi16(acc, zero));
// multiplication is significantly faster than division
acc = _mm_cvtps_epi32(_mm_mul_ps(_mm_cvtepi32_ps(acc),
_mm_set1_ps(1/((float)KERNEL_SIZE))));