1 /*
2 * Copyright 2014
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 #include "SkTextureCompressor.h"
9 #include "SkTextureCompression_opts.h"
10
11 #include <arm_neon.h>
12
13 // Converts indices in each of the four bits of the register from
14 // 0, 1, 2, 3, 4, 5, 6, 7
15 // to
16 // 3, 2, 1, 0, 4, 5, 6, 7
17 //
18 // A more detailed explanation can be found in SkTextureCompressor::convert_indices
convert_indices(const uint8x16_t & x)19 static inline uint8x16_t convert_indices(const uint8x16_t &x) {
20 static const int8x16_t kThree = {
21 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
22 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
23 };
24
25 static const int8x16_t kZero = {
26 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
27 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
28 };
29
30 // Take top three bits
31 int8x16_t sx = vreinterpretq_s8_u8(x);
32
33 // Negate ...
34 sx = vnegq_s8(sx);
35
36 // Add three...
37 sx = vaddq_s8(sx, kThree);
38
39 // Generate negatives mask
40 const int8x16_t mask = vreinterpretq_s8_u8(vcltq_s8(sx, kZero));
41
42 // Absolute value
43 sx = vabsq_s8(sx);
44
45 // Add three to the values that were negative...
46 return vreinterpretq_u8_s8(vaddq_s8(sx, vandq_s8(mask, kThree)));
47 }
48
49 template<unsigned shift>
shift_swap(const uint64x2_t & x,const uint64x2_t & mask)50 static inline uint64x2_t shift_swap(const uint64x2_t &x, const uint64x2_t &mask) {
51 uint64x2_t t = vandq_u64(mask, veorq_u64(x, vshrq_n_u64(x, shift)));
52 return veorq_u64(x, veorq_u64(t, vshlq_n_u64(t, shift)));
53 }
54
pack_indices(const uint64x2_t & x)55 static inline uint64x2_t pack_indices(const uint64x2_t &x) {
56 // x: 00 a e 00 b f 00 c g 00 d h 00 i m 00 j n 00 k o 00 l p
57
58 static const uint64x2_t kMask1 = { 0x3FC0003FC00000ULL, 0x3FC0003FC00000ULL };
59 uint64x2_t ret = shift_swap<10>(x, kMask1);
60
61 // x: b f 00 00 00 a e c g i m 00 00 00 d h j n 00 k o 00 l p
62 static const uint64x2_t kMask2 = { (0x3FULL << 52), (0x3FULL << 52) };
63 static const uint64x2_t kMask3 = { (0x3FULL << 28), (0x3FULL << 28) };
64 const uint64x2_t x1 = vandq_u64(vshlq_n_u64(ret, 52), kMask2);
65 const uint64x2_t x2 = vandq_u64(vshlq_n_u64(ret, 20), kMask3);
66 ret = vshrq_n_u64(vorrq_u64(ret, vorrq_u64(x1, x2)), 16);
67
68 // x: 00 00 00 00 00 00 00 00 b f l p a e c g i m k o d h j n
69
70 static const uint64x2_t kMask4 = { 0xFC0000ULL, 0xFC0000ULL };
71 ret = shift_swap<6>(ret, kMask4);
72
73 #if defined (SK_CPU_BENDIAN)
74 // x: 00 00 00 00 00 00 00 00 b f l p a e i m c g k o d h j n
75
76 static const uint64x2_t kMask5 = { 0x3FULL, 0x3FULL };
77 ret = shift_swap<36>(ret, kMask5);
78
79 // x: 00 00 00 00 00 00 00 00 b f j n a e i m c g k o d h l p
80
81 static const uint64x2_t kMask6 = { 0xFFF000000ULL, 0xFFF000000ULL };
82 ret = shift_swap<12>(ret, kMask6);
83 #else
84 // x: 00 00 00 00 00 00 00 00 c g i m d h l p b f j n a e k o
85
86 static const uint64x2_t kMask5 = { 0xFC0ULL, 0xFC0ULL };
87 ret = shift_swap<36>(ret, kMask5);
88
89 // x: 00 00 00 00 00 00 00 00 a e i m d h l p b f j n c g k o
90
91 static const uint64x2_t kMask6 = { (0xFFFULL << 36), (0xFFFULL << 36) };
92 static const uint64x2_t kMask7 = { 0xFFFFFFULL, 0xFFFFFFULL };
93 static const uint64x2_t kMask8 = { 0xFFFULL, 0xFFFULL };
94 const uint64x2_t y1 = vandq_u64(ret, kMask6);
95 const uint64x2_t y2 = vshlq_n_u64(vandq_u64(ret, kMask7), 12);
96 const uint64x2_t y3 = vandq_u64(vshrq_n_u64(ret, 24), kMask8);
97 ret = vorrq_u64(y1, vorrq_u64(y2, y3));
98 #endif
99
100 // x: 00 00 00 00 00 00 00 00 a e i m b f j n c g k o d h l p
101
102 // Set the header
103 static const uint64x2_t kHeader = { 0x8490000000000000ULL, 0x8490000000000000ULL };
104 return vorrq_u64(kHeader, ret);
105 }
106
107 // Takes a row of alpha values and places the most significant three bits of each byte into
108 // the least significant bits of the same byte
make_index_row(const uint8x16_t & x)109 static inline uint8x16_t make_index_row(const uint8x16_t &x) {
110 static const uint8x16_t kTopThreeMask = {
111 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0,
112 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0,
113 };
114 return vshrq_n_u8(vandq_u8(x, kTopThreeMask), 5);
115 }
116
117 // Returns true if all of the bits in x are 0.
is_zero(uint8x16_t x)118 static inline bool is_zero(uint8x16_t x) {
119 // First experiments say that this is way slower than just examining the lanes
120 // but it might need a little more investigation.
121 #if 0
122 // This code path tests the system register for overflow. We trigger
123 // overflow by adding x to a register with all of its bits set. The
124 // first instruction sets the bits.
125 int reg;
126 asm ("VTST.8 %%q0, %q1, %q1\n"
127 "VQADD.u8 %q1, %%q0\n"
128 "VMRS %0, FPSCR\n"
129 : "=r"(reg) : "w"(vreinterpretq_f32_u8(x)) : "q0", "q1");
130
131 // Bit 21 corresponds to the overflow flag.
132 return reg & (0x1 << 21);
133 #else
134 const uint64x2_t cvt = vreinterpretq_u64_u8(x);
135 const uint64_t l1 = vgetq_lane_u64(cvt, 0);
136 return (l1 == 0) && (l1 == vgetq_lane_u64(cvt, 1));
137 #endif
138 }
139
140 #if defined (SK_CPU_BENDIAN)
fix_endianness(uint64x2_t x)141 static inline uint64x2_t fix_endianness(uint64x2_t x) {
142 return x;
143 }
144 #else
fix_endianness(uint64x2_t x)145 static inline uint64x2_t fix_endianness(uint64x2_t x) {
146 return vreinterpretq_u64_u8(vrev64q_u8(vreinterpretq_u8_u64(x)));
147 }
148 #endif
149
compress_r11eac_blocks(uint64_t * dst,const uint8_t * src,size_t rowBytes)150 static void compress_r11eac_blocks(uint64_t* dst, const uint8_t* src, size_t rowBytes) {
151
152 // Try to avoid switching between vector and non-vector ops...
153 const uint8_t *const src1 = src;
154 const uint8_t *const src2 = src + rowBytes;
155 const uint8_t *const src3 = src + 2*rowBytes;
156 const uint8_t *const src4 = src + 3*rowBytes;
157 uint64_t *const dst1 = dst;
158 uint64_t *const dst2 = dst + 2;
159
160 const uint8x16_t alphaRow1 = vld1q_u8(src1);
161 const uint8x16_t alphaRow2 = vld1q_u8(src2);
162 const uint8x16_t alphaRow3 = vld1q_u8(src3);
163 const uint8x16_t alphaRow4 = vld1q_u8(src4);
164
165 const uint8x16_t cmp12 = vceqq_u8(alphaRow1, alphaRow2);
166 const uint8x16_t cmp34 = vceqq_u8(alphaRow3, alphaRow4);
167 const uint8x16_t cmp13 = vceqq_u8(alphaRow1, alphaRow3);
168
169 const uint8x16_t cmp = vandq_u8(vandq_u8(cmp12, cmp34), cmp13);
170 const uint8x16_t ncmp = vmvnq_u8(cmp);
171 const uint8x16_t nAlphaRow1 = vmvnq_u8(alphaRow1);
172 if (is_zero(ncmp)) {
173 if (is_zero(alphaRow1)) {
174 static const uint64x2_t kTransparent = { 0x0020000000002000ULL,
175 0x0020000000002000ULL };
176 vst1q_u64(dst1, kTransparent);
177 vst1q_u64(dst2, kTransparent);
178 return;
179 } else if (is_zero(nAlphaRow1)) {
180 vst1q_u64(dst1, vreinterpretq_u64_u8(cmp));
181 vst1q_u64(dst2, vreinterpretq_u64_u8(cmp));
182 return;
183 }
184 }
185
186 const uint8x16_t indexRow1 = convert_indices(make_index_row(alphaRow1));
187 const uint8x16_t indexRow2 = convert_indices(make_index_row(alphaRow2));
188 const uint8x16_t indexRow3 = convert_indices(make_index_row(alphaRow3));
189 const uint8x16_t indexRow4 = convert_indices(make_index_row(alphaRow4));
190
191 const uint64x2_t indexRow12 = vreinterpretq_u64_u8(
192 vorrq_u8(vshlq_n_u8(indexRow1, 3), indexRow2));
193 const uint64x2_t indexRow34 = vreinterpretq_u64_u8(
194 vorrq_u8(vshlq_n_u8(indexRow3, 3), indexRow4));
195
196 const uint32x4x2_t blockIndices = vtrnq_u32(vreinterpretq_u32_u64(indexRow12),
197 vreinterpretq_u32_u64(indexRow34));
198 const uint64x2_t blockIndicesLeft = vreinterpretq_u64_u32(vrev64q_u32(blockIndices.val[0]));
199 const uint64x2_t blockIndicesRight = vreinterpretq_u64_u32(vrev64q_u32(blockIndices.val[1]));
200
201 const uint64x2_t indicesLeft = fix_endianness(pack_indices(blockIndicesLeft));
202 const uint64x2_t indicesRight = fix_endianness(pack_indices(blockIndicesRight));
203
204 const uint64x2_t d1 = vcombine_u64(vget_low_u64(indicesLeft), vget_low_u64(indicesRight));
205 const uint64x2_t d2 = vcombine_u64(vget_high_u64(indicesLeft), vget_high_u64(indicesRight));
206 vst1q_u64(dst1, d1);
207 vst1q_u64(dst2, d2);
208 }
209
CompressA8toR11EAC_NEON(uint8_t * dst,const uint8_t * src,int width,int height,size_t rowBytes)210 bool CompressA8toR11EAC_NEON(uint8_t* dst, const uint8_t* src,
211 int width, int height, size_t rowBytes) {
212
213 // Since we're going to operate on 4 blocks at a time, the src width
214 // must be a multiple of 16. However, the height only needs to be a
215 // multiple of 4
216 if (0 == width || 0 == height || (width % 16) != 0 || (height % 4) != 0) {
217 return SkTextureCompressor::CompressBufferToFormat(
218 dst, src,
219 kAlpha_8_SkColorType,
220 width, height, rowBytes,
221 SkTextureCompressor::kR11_EAC_Format, false);
222 }
223
224 const int blocksX = width >> 2;
225 const int blocksY = height >> 2;
226
227 SkASSERT((blocksX % 4) == 0);
228
229 uint64_t* encPtr = reinterpret_cast<uint64_t*>(dst);
230 for (int y = 0; y < blocksY; ++y) {
231 for (int x = 0; x < blocksX; x+=4) {
232 // Compress it
233 compress_r11eac_blocks(encPtr, src + 4*x, rowBytes);
234 encPtr += 4;
235 }
236 src += 4 * rowBytes;
237 }
238 return true;
239 }
240