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| 1 /* |
| 2 * Copyright 2016 Google Inc. |
| 3 * |
| 4 * Use of this source code is governed by a BSD-style license that can be |
| 5 * found in the LICENSE file. |
| 6 */ |
| 7 |
| 8 #ifndef SkSwizzler_opts_DEFINED |
| 9 #define SkSwizzler_opts_DEFINED |
| 10 |
| 11 #include "SkColorPriv.h" |
| 12 |
| 13 namespace SK_OPTS_NS { |
| 14 |
| 15 // These variable names in these functions just pretend the input is BGRA. |
| 16 // They work fine with both RGBA and BGRA. |
| 17 |
| 18 static void premul_xxxa_portable(uint32_t dst[], const uint32_t src[], int count
) { |
| 19 for (int i = 0; i < count; i++) { |
| 20 uint8_t a = src[i] >> 24, |
| 21 r = src[i] >> 16, |
| 22 g = src[i] >> 8, |
| 23 b = src[i] >> 0; |
| 24 r = (r*a+127)/255; |
| 25 g = (g*a+127)/255; |
| 26 b = (b*a+127)/255; |
| 27 dst[i] = (uint32_t)a << 24 |
| 28 | (uint32_t)r << 16 |
| 29 | (uint32_t)g << 8 |
| 30 | (uint32_t)b << 0; |
| 31 } |
| 32 } |
| 33 |
| 34 static void premul_swaprb_xxxa_portable(uint32_t dst[], const uint32_t src[], in
t count) { |
| 35 for (int i = 0; i < count; i++) { |
| 36 uint8_t a = src[i] >> 24, |
| 37 r = src[i] >> 16, |
| 38 g = src[i] >> 8, |
| 39 b = src[i] >> 0; |
| 40 r = (r*a+127)/255; |
| 41 g = (g*a+127)/255; |
| 42 b = (b*a+127)/255; |
| 43 dst[i] = (uint32_t)a << 24 |
| 44 | (uint32_t)b << 16 |
| 45 | (uint32_t)g << 8 |
| 46 | (uint32_t)r << 0; |
| 47 } |
| 48 } |
| 49 |
| 50 #if defined(SK_ARM_HAS_NEON) |
| 51 |
| 52 // Rounded divide by 255, (x + 127) / 255 |
| 53 static uint8x8_t div255_round(uint16x8_t x) { |
| 54 // result = (x + 127) / 255 |
| 55 // result = (x + 127) / 256 + error1 |
| 56 // |
| 57 // error1 = (x + 127) / (255 * 256) |
| 58 // error1 = (x + 127) / (256 * 256) + error2 |
| 59 // |
| 60 // error2 = (x + 127) / (255 * 256 * 256) |
| 61 // |
| 62 // The maximum value of error2 is too small to matter. Thus: |
| 63 // result = (x + 127) / 256 + (x + 127) / (256 * 256) |
| 64 // result = ((x + 127) / 256 + x + 127) / 256 |
| 65 // result = ((x + 127) >> 8 + x + 127) >> 8 |
| 66 // |
| 67 // Use >>> to represent "rounded right shift" which, conveniently, |
| 68 // NEON supports in one instruction. |
| 69 // result = ((x >>> 8) + x) >>> 8 |
| 70 // |
| 71 // Note that the second right shift is actually performed as an |
| 72 // "add, round, and narrow back to 8-bits" instruction. |
| 73 return vraddhn_u16(x, vrshrq_n_u16(x, 8)); |
| 74 } |
| 75 |
| 76 // Scale a byte by another, (x * y + 127) / 255 |
| 77 static uint8x8_t scale(uint8x8_t x, uint8x8_t y) { |
| 78 return div255_round(vmull_u8(x, y)); |
| 79 } |
| 80 |
| 81 template <bool kSwapRB> |
| 82 static void premul_xxxa_should_swaprb(uint32_t dst[], const uint32_t src[], int
count) { |
| 83 while (count >= 8) { |
| 84 // Load 8 pixels. |
| 85 uint8x8x4_t bgra = vld4_u8((const uint8_t*) src); |
| 86 |
| 87 uint8x8_t a = bgra.val[3], |
| 88 r = bgra.val[2], |
| 89 g = bgra.val[1], |
| 90 b = bgra.val[0]; |
| 91 |
| 92 // Premultiply. |
| 93 r = scale(r, a); |
| 94 g = scale(g, a); |
| 95 b = scale(b, a); |
| 96 |
| 97 // Store 8 premultiplied pixels. |
| 98 if (kSwapRB) { |
| 99 bgra.val[2] = b; |
| 100 bgra.val[1] = g; |
| 101 bgra.val[0] = r; |
| 102 } else { |
| 103 bgra.val[2] = r; |
| 104 bgra.val[1] = g; |
| 105 bgra.val[0] = b; |
| 106 } |
| 107 vst4_u8((uint8_t*) dst, bgra); |
| 108 src += 8; |
| 109 dst += 8; |
| 110 count -= 8; |
| 111 } |
| 112 |
| 113 // Call portable code to finish up the tail of [0,8) pixels. |
| 114 auto proc = kSwapRB ? premul_swaprb_xxxa_portable : premul_xxxa_portable; |
| 115 proc(dst, src, count); |
| 116 } |
| 117 |
| 118 static void premul_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| 119 premul_xxxa_should_swaprb<false>(dst, src, count); |
| 120 } |
| 121 |
| 122 static void premul_swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count)
{ |
| 123 premul_xxxa_should_swaprb<true>(dst, src, count); |
| 124 } |
| 125 |
| 126 #else |
| 127 |
| 128 static void premul_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| 129 premul_xxxa_portable(dst, src, count); |
| 130 } |
| 131 |
| 132 static void premul_swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count)
{ |
| 133 premul_swaprb_xxxa_portable(dst, src, count); |
| 134 } |
| 135 |
| 136 #endif |
| 137 |
| 138 static void swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) { |
| 139 for (int i = 0; i < count; i++) { |
| 140 uint8_t a = src[i] >> 24, |
| 141 r = src[i] >> 16, |
| 142 g = src[i] >> 8, |
| 143 b = src[i] >> 0; |
| 144 dst[i] = (uint32_t)a << 24 |
| 145 | (uint32_t)b << 16 |
| 146 | (uint32_t)g << 8 |
| 147 | (uint32_t)r << 0; |
| 148 } |
| 149 } |
| 150 |
| 151 } |
| 152 |
| 153 #endif // SkSwizzler_opts_DEFINED |
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