/* * vim:ts=4:sw=4:expandtab * * © 2016 Sebastian Frysztak * * See LICENSE for licensing information * */ #include "blur.h" #include #include #include #include #define ALIGN16 __attribute__((aligned(16))) #define KERNEL_SIZE 15 #define HALF_KERNEL KERNEL_SIZE / 2 // number of xmm registers needed to store // 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]; 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) { uint32_t* o_src = src; for (int row = 0; row < height; row++) { for (int column = 0; column < width; column++, src++) { __m128i rgbaIn[REGISTERS_CNT]; // handle borders int leftBorder = column < HALF_KERNEL; int rightBorder = column > width - HALF_KERNEL; if (leftBorder || rightBorder) { uint32_t _rgbaIn[KERNEL_SIZE + 1] ALIGN16; 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++) { #if 0 printf("%p -> %p (%ld) || %p->%p\n", o_src, o_src + (height * width), o_src + (height * width) - src, src + 4*k - HALF_KERNEL, ((__m128i*)src + 4*k - HALF_KERNEL) + 1 ); #endif // if this copy would go out of bounds, break if ((long long) (((__m128i*) src + 4*k - HALF_KERNEL) + 1) > (long long) (o_src + (height * width))) break; rgbaIn[k] = _mm_loadu_si128((__m128i*)(src + 4*k - HALF_KERNEL)); } } // 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; for (int i = 0; i < 3; i++) { tmp = _mm_unpacklo_epi8(rgbaIn[i], 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(rgbaIn[i], 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(rgbaIn[3], 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(rgbaIn[3], 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); } } } 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) { uint32_t* o_src = src; __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 + 1] ALIGN16; #if 0 for (int j = 0; j < KERNEL_SIZE; ++j) { printf("_rgbaIn[%d]: %p->%p\n", j, &_rgbaIn[j], &_rgbaIn[j] + 1); } #endif // 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++) { #if 0 printf("K: %d; p: %p, p+4*k: %p, end of p: %p\n", k, _rgbaIn, _rgbaIn+4*k, ((__m128i*) (_rgbaIn +4*k)) + 1); #endif rgbaIn[k] = _mm_load_si128((__m128i*)(_rgbaIn + 4*k)); } } else { for (int k = 0; k < REGISTERS_CNT; k++) { if ((long long) (((__m128i*) src + 4*k - HALF_KERNEL) + 1) > (long long) (o_src + (height * width))) break; #if 0 printf("K: %d; p: %p -> %p\n", k, src+4*k - HALF_KERNEL, ((__m128i*) (src +4*k - HALF_KERNEL)) + 1); printf("%p->%p, %p->%p (%ld)\n", (__m128i*) src + 4*k - HALF_KERNEL, ((__m128i*) src + 4*k - HALF_KERNEL) + 1, o_src, o_src + (width * height), o_src + (width * height) - src); #endif 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; } } }