diff --git a/Makefile b/Makefile index b0a3dcc..d979100 100644 --- a/Makefile +++ b/Makefile @@ -14,6 +14,7 @@ endif CFLAGS += -std=c99 CFLAGS += -pipe CFLAGS += -Wall +CFLAGS += -mssse3 CFLAGS += -O2 CPPFLAGS += -D_GNU_SOURCE CPPFLAGS += -DXKBCOMPOSE=$(shell if test -e /usr/include/xkbcommon/xkbcommon-compose.h ; then echo 1 ; else echo 0 ; fi ) diff --git a/blur.c b/blur.c index d91f57d..a5b0bd3 100644 --- a/blur.c +++ b/blur.c @@ -70,7 +70,8 @@ blur_image_surface (cairo_surface_t *surface, int radius) dst_stride = cairo_image_surface_get_stride (tmp); //blur_impl_naive(src, dst, width, height, src_stride, dst_stride, 10000); - blur_impl_sse2(src, dst, width, height, 4.5); + //blur_impl_sse2(src, dst, width, height, 4.5); + blur_impl_ssse3(src, dst, width, height, 4.5); cairo_surface_destroy (tmp); cairo_surface_flush (surface); diff --git a/blur.h b/blur.h index 2a5f45c..478e2f0 100644 --- a/blur.h +++ b/blur.h @@ -8,6 +8,8 @@ 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_ssse3(uint32_t* src, uint32_t* dst, int width, int height, float sigma); +void blur_impl_horizontal_pass_ssse3(uint32_t *src, uint32_t *dst, int8_t *kernel, int width, int height); #endif diff --git a/blur_simd.c b/blur_simd.c index 4cacb9a..7dcd9a4 100644 --- a/blur_simd.c +++ b/blur_simd.c @@ -10,6 +10,7 @@ #include "blur.h" #include #include +#include #define ALIGN16 __attribute__((aligned(16))) #define KERNEL_SIZE 15 @@ -19,6 +20,11 @@ // input pixels for given kernel size #define REGISTERS_CNT (KERNEL_SIZE + 4/2) / 4 +// scaling factor for kernel coefficients. +// higher values cause desaturation. +// used in SSSE3 implementation. +#define SCALE_FACTOR 7 + void blur_impl_sse2(uint32_t *src, uint32_t *dst, int width, int height, float sigma) { // prepare kernel float kernel[KERNEL_SIZE]; @@ -117,3 +123,128 @@ void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, float *kernel, } } } + +void blur_impl_ssse3(uint32_t *src, uint32_t *dst, int width, int height, float sigma) { + // prepare kernel + float kernelf[KERNEL_SIZE]; + int8_t kernel[KERNEL_SIZE + 1]; + 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; + kernelf[i] = coeff * expf(-x * x / (2.0 * sigma * sigma)); + sum += kernelf[i]; + } + + // normalize kernel + for (int i = 0; i < KERNEL_SIZE; i++) + kernelf[i] /= sum; + + // round to nearest integer and convert to int + for (int i = 0; i < KERNEL_SIZE; i++) + kernel[i] = (int8_t)rintf(kernelf[i] * (1 << SCALE_FACTOR)); + kernel[KERNEL_SIZE] = 0; + + // 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_ssse3(src, dst, kernel, width, height); + blur_impl_horizontal_pass_ssse3(dst, src, kernel, height, width); +} + + +void blur_impl_horizontal_pass_ssse3(uint32_t *src, uint32_t *dst, int8_t *kernel, int width, int height) { + __m128i _kern = _mm_loadu_si128((__m128i*)kernel); + __m128i rgbaIn[REGISTERS_CNT]; + + for (int row = 0; row < height; row++) { + for (int column = 0; column < width; column++, src++) { + uint32_t _rgbaIn[KERNEL_SIZE] ALIGN16; + // handle borders + int leftBorder = column < HALF_KERNEL; + int rightBorder = column > width - HALF_KERNEL; + if (leftBorder || rightBorder) { + int i = 0; + if (leftBorder) { + // for kernel size 7x7 and column == 0, we have: + // x x x P0 P1 P2 P3 + // first loop mirrors P{0..3} to fill x's, + // second one loads P{0..3} + for (; i < HALF_KERNEL - column; i++) + _rgbaIn[i] = *(src + (HALF_KERNEL - i)); + for (; i < KERNEL_SIZE; i++) + _rgbaIn[i] = *(src - (HALF_KERNEL - i)); + } else { + for (; i < width - column; i++) + _rgbaIn[i] = *(src + i); + for (int k = 0; i < KERNEL_SIZE; i++, k++) + _rgbaIn[i] = *(src - k); + } + + for (int k = 0; k < REGISTERS_CNT; k++) + rgbaIn[k] = _mm_load_si128((__m128i*)(_rgbaIn + 4*k)); + } else { + for (int k = 0; k < REGISTERS_CNT; k++) + rgbaIn[k] = _mm_loadu_si128((__m128i*)(src + 4*k - HALF_KERNEL)); + } + + // basis of this implementation is _mm_maddubs_epi16 (aka pmaddubsw). + // 'rgba' holds 16 unsigned bytes, so 4 pixels. + // 'kern' holds 16 signed bytes kernel values multiplied by (1 << SCALE_FACTOR). + // before multiplication takes place, vectors need to be prepared: + // 'rgba' is shuffled from R1B1G1A1...R4B4G4A4 to R1R2R3R4...A1A2A3A4 + // 'kern' is shuffled from w1w2w3w4...w13w14w15w16 to w1w2w3w4 repeated 4 times + // then we call _mm_maddubs_epi16 and we get: + // -------------------------------------------------------------------------------------- + // | R1*w1 + R2*w2 | R3*w3 + R4*w4 | G1*w1 + G2*w2 | G3*w3 + G4*w4 | repeat for B and A | + // -------------------------------------------------------------------------------------- + // each 'rectangle' is a 16-byte signed int. + // then we repeat the process for the rest of input pixels, + // call _mm_hadds_epi16 to add adjacent ints and shift right to scale by SCALE_FACTOR. + + __m128i rgba, kern; + __m128i zero = _mm_setzero_si128(); + __m128i acc = _mm_setzero_si128(); + + const __m128i rgba_shuf_mask = _mm_setr_epi8(0, 4, 8, 12, + 1, 5, 9, 13, + 2, 6, 10, 14, + 3, 7, 11, 15); + + const __m128i kern_shuf_mask = _mm_setr_epi8(0, 1, 2, 3, + 0, 1, 2, 3, + 0, 1, 2, 3, + 0, 1, 2, 3); + + rgba = _mm_shuffle_epi8(rgbaIn[0], rgba_shuf_mask); + kern = _mm_shuffle_epi8(_kern, kern_shuf_mask); + acc = _mm_adds_epi16(acc, _mm_maddubs_epi16(rgba, kern)); + + rgba = _mm_shuffle_epi8(rgbaIn[1], rgba_shuf_mask); + kern = _mm_shuffle_epi8(_mm_srli_si128(_kern, 4), kern_shuf_mask); + acc = _mm_adds_epi16(acc, _mm_maddubs_epi16(rgba, kern)); + + rgba = _mm_shuffle_epi8(rgbaIn[2], rgba_shuf_mask); + kern = _mm_shuffle_epi8(_mm_srli_si128(_kern, 8), kern_shuf_mask); + acc = _mm_adds_epi16(acc, _mm_maddubs_epi16(rgba, kern)); + + rgba = _mm_shuffle_epi8(rgbaIn[3], rgba_shuf_mask); + kern = _mm_shuffle_epi8(_mm_srli_si128(_kern, 12), kern_shuf_mask); + acc = _mm_adds_epi16(acc, _mm_maddubs_epi16(rgba, kern)); + + acc = _mm_hadds_epi16(acc, zero); + acc = _mm_srai_epi16(acc, SCALE_FACTOR); + + // Cairo sets alpha channel to 255 + // (or -1, depending how you look at it) + // this quickly overflows accumulator, + // and alpha is calculated completely wrong. + // I assume most people don't use semi-transparent + // lock screen images, so no one will mind if we + // 'correct it' by setting alpha to 255. + *(dst + height * column + row) = + _mm_cvtsi128_si32(_mm_packus_epi16(acc, zero)) | 0xFF000000; + } + } +}