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/*
* 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;
}
}
static void 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;
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);
}
static void swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) {
while (count >= 16) {
// Load 16 pixels.
uint8x16x4_t bgra = vld4q_u8((const uint8_t*) src);
// Swap r and b.
SkTSwap(bgra.val[0], bgra.val[2]);
// Store 16 pixels.
vst4q_u8((uint8_t*) dst, bgra);
src += 16;
dst += 16;
count -= 16;
}
if (count >= 8) {
// Load 8 pixels.
uint8x8x4_t bgra = vld4_u8((const uint8_t*) src);
// Swap r and b.
SkTSwap(bgra.val[0], bgra.val[2]);
// Store 8 pixels.
vst4_u8((uint8_t*) dst, bgra);
src += 8;
dst += 8;
count -= 8;
}
swaprb_xxxa_portable(dst, src, count);
}
#elif SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSSE3
template <bool kSwapRB>
static void premul_xxxa_should_swaprb(uint32_t dst[], const uint32_t src[], int count) {
auto premul8 = [](__m128i* lo, __m128i* hi) {
const __m128i zeros = _mm_setzero_si128();
const __m128i _128 = _mm_set1_epi16(128);
const __m128i _257 = _mm_set1_epi16(257);
__m128i planar;
if (kSwapRB) {
planar = _mm_setr_epi8(2,6,10,14, 1,5,9,13, 0,4,8,12, 3,7,11,15);
} else {
planar = _mm_setr_epi8(0,4,8,12, 1,5,9,13, 2,6,10,14, 3,7,11,15);
}
// Swizzle the pixels to 8-bit planar.
*lo = _mm_shuffle_epi8(*lo, planar); // bbbbgggg rrrraaaa
*hi = _mm_shuffle_epi8(*hi, planar); // BBBBGGGG RRRRAAAA
__m128i bg = _mm_unpacklo_epi32(*lo, *hi), // bbbbBBBB ggggGGGG
ra = _mm_unpackhi_epi32(*lo, *hi); // rrrrRRRR aaaaAAAA
// Unpack to 16-bit planar.
__m128i b = _mm_unpacklo_epi8(bg, zeros), // b_b_b_b_ B_B_B_B_
g = _mm_unpackhi_epi8(bg, zeros), // g_g_g_g_ G_G_G_G_
r = _mm_unpacklo_epi8(ra, zeros), // r_r_r_r_ R_R_R_R_
a = _mm_unpackhi_epi8(ra, zeros); // a_a_a_a_ A_A_A_A_
// Premultiply! (x+127)/255 == ((x+128)*257)>>16 for 0 <= x <= 255*255.
b = _mm_mulhi_epu16(_mm_add_epi16(_mm_mullo_epi16(b, a), _128), _257);
g = _mm_mulhi_epu16(_mm_add_epi16(_mm_mullo_epi16(g, a), _128), _257);
r = _mm_mulhi_epu16(_mm_add_epi16(_mm_mullo_epi16(r, a), _128), _257);
// Repack into interlaced pixels.
bg = _mm_or_si128(b, _mm_slli_epi16(g, 8)); // bgbgbgbg BGBGBGBG
ra = _mm_or_si128(r, _mm_slli_epi16(a, 8)); // rararara RARARARA
*lo = _mm_unpacklo_epi16(bg, ra); // bgrabgra bgrabgra
*hi = _mm_unpackhi_epi16(bg, ra); // BRGABGRA BGRABGRA
};
while (count >= 8) {
__m128i lo = _mm_loadu_si128((const __m128i*) (src + 0)),
hi = _mm_loadu_si128((const __m128i*) (src + 4));
premul8(&lo, &hi);
_mm_storeu_si128((__m128i*) (dst + 0), lo);
_mm_storeu_si128((__m128i*) (dst + 4), hi);
src += 8;
dst += 8;
count -= 8;
}
if (count >= 4) {
__m128i lo = _mm_loadu_si128((const __m128i*) src),
hi = _mm_setzero_si128();
premul8(&lo, &hi);
_mm_storeu_si128((__m128i*) dst, lo);
src += 4;
dst += 4;
count -= 4;
}
// Call portable code to finish up the tail of [0,4) 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);
}
static void swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) {
const __m128i swapRB = _mm_setr_epi8(2,1,0,3, 6,5,4,7, 10,9,8,11, 14,13,12,15);
while (count >= 4) {
__m128i bgra = _mm_loadu_si128((const __m128i*) src);
__m128i rgba = _mm_shuffle_epi8(bgra, swapRB);
_mm_storeu_si128((__m128i*) dst, rgba);
src += 4;
dst += 4;
count -= 4;
}
swaprb_xxxa_portable(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);
}
static void swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) {
swaprb_xxxa_portable(dst, src, count);
}
#endif
}
#endif // SkSwizzler_opts_DEFINED
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