| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkSwizzler_opts_DEFINED |
| #define SkSwizzler_opts_DEFINED |
| |
| #include "SkColorPriv.h" |
| |
| namespace SK_OPTS_NS { |
| |
| // These variable names in these functions just pretend the input is BGRA. |
| // They work fine with both RGBA and BGRA. |
| |
| static void premul_xxxa_portable(uint32_t dst[], const uint32_t src[], int count) { |
| for (int i = 0; i < count; i++) { |
| uint8_t a = src[i] >> 24, |
| r = src[i] >> 16, |
| g = src[i] >> 8, |
| b = src[i] >> 0; |
| r = (r*a+127)/255; |
| g = (g*a+127)/255; |
| b = (b*a+127)/255; |
| dst[i] = (uint32_t)a << 24 |
| | (uint32_t)r << 16 |
| | (uint32_t)g << 8 |
| | (uint32_t)b << 0; |
| } |
| } |
| |
| static void premul_swaprb_xxxa_portable(uint32_t dst[], const uint32_t src[], int count) { |
| for (int i = 0; i < count; i++) { |
| uint8_t a = src[i] >> 24, |
| r = src[i] >> 16, |
| g = src[i] >> 8, |
| b = src[i] >> 0; |
| r = (r*a+127)/255; |
| g = (g*a+127)/255; |
| b = (b*a+127)/255; |
| dst[i] = (uint32_t)a << 24 |
| | (uint32_t)b << 16 |
| | (uint32_t)g << 8 |
| | (uint32_t)r << 0; |
| } |
| } |
| |
| #if defined(SK_ARM_HAS_NEON) |
| |
| // Rounded divide by 255, (x + 127) / 255 |
| static uint8x8_t div255_round(uint16x8_t x) { |
| // result = (x + 127) / 255 |
| // result = (x + 127) / 256 + error1 |
| // |
| // error1 = (x + 127) / (255 * 256) |
| // error1 = (x + 127) / (256 * 256) + error2 |
| // |
| // error2 = (x + 127) / (255 * 256 * 256) |
| // |
| // The maximum value of error2 is too small to matter. Thus: |
| // result = (x + 127) / 256 + (x + 127) / (256 * 256) |
| // result = ((x + 127) / 256 + x + 127) / 256 |
| // result = ((x + 127) >> 8 + x + 127) >> 8 |
| // |
| // Use >>> to represent "rounded right shift" which, conveniently, |
| // NEON supports in one instruction. |
| // result = ((x >>> 8) + x) >>> 8 |
| // |
| // Note that the second right shift is actually performed as an |
| // "add, round, and narrow back to 8-bits" instruction. |
| return vraddhn_u16(x, vrshrq_n_u16(x, 8)); |
| } |
| |
| // Scale a byte by another, (x * y + 127) / 255 |
| static uint8x8_t scale(uint8x8_t x, uint8x8_t y) { |
| return div255_round(vmull_u8(x, y)); |
| } |
| |
| template <bool kSwapRB> |
| static void premul_xxxa_should_swaprb(uint32_t dst[], const uint32_t src[], int count) { |
| while (count >= 8) { |
| // Load 8 pixels. |
| uint8x8x4_t bgra = vld4_u8((const uint8_t*) src); |
| |
| uint8x8_t a = bgra.val[3], |
| r = bgra.val[2], |
| g = bgra.val[1], |
| b = bgra.val[0]; |
| |
| // Premultiply. |
| r = scale(r, a); |
| g = scale(g, a); |
| b = scale(b, a); |
| |
| // Store 8 premultiplied pixels. |
| if (kSwapRB) { |
| bgra.val[2] = b; |
| bgra.val[1] = g; |
| bgra.val[0] = r; |
| } else { |
| bgra.val[2] = r; |
| bgra.val[1] = g; |
| bgra.val[0] = b; |
| } |
| vst4_u8((uint8_t*) dst, bgra); |
| src += 8; |
| dst += 8; |
| count -= 8; |
| } |
| |
| // Call portable code to finish up the tail of [0,8) pixels. |
| auto proc = kSwapRB ? premul_swaprb_xxxa_portable : premul_xxxa_portable; |
| proc(dst, src, count); |
| } |
| |
| static void premul_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| premul_xxxa_should_swaprb<false>(dst, src, count); |
| } |
| |
| static void premul_swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| premul_xxxa_should_swaprb<true>(dst, src, count); |
| } |
| |
| #else |
| |
| static void premul_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| premul_xxxa_portable(dst, src, count); |
| } |
| |
| static void premul_swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| premul_swaprb_xxxa_portable(dst, src, count); |
| } |
| |
| #endif |
| |
| static void swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| for (int i = 0; i < count; i++) { |
| uint8_t a = src[i] >> 24, |
| r = src[i] >> 16, |
| g = src[i] >> 8, |
| b = src[i] >> 0; |
| dst[i] = (uint32_t)a << 24 |
| | (uint32_t)b << 16 |
| | (uint32_t)g << 8 |
| | (uint32_t)r << 0; |
| } |
| } |
| |
| } |
| |
| #endif // SkSwizzler_opts_DEFINED |