1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkPackBits.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,411 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2011 Google Inc.
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +#include "SkPackBits.h"
1.12 +
1.13 +#define GATHER_STATSx
1.14 +
1.15 +static inline void small_memcpy(void* SK_RESTRICT dst,
1.16 + const void* SK_RESTRICT src, int n) {
1.17 + SkASSERT(n > 0 && n <= 15);
1.18 + uint8_t* d = (uint8_t*)dst;
1.19 + const uint8_t* s = (const uint8_t*)src;
1.20 + switch (n) {
1.21 + case 15: *d++ = *s++;
1.22 + case 14: *d++ = *s++;
1.23 + case 13: *d++ = *s++;
1.24 + case 12: *d++ = *s++;
1.25 + case 11: *d++ = *s++;
1.26 + case 10: *d++ = *s++;
1.27 + case 9: *d++ = *s++;
1.28 + case 8: *d++ = *s++;
1.29 + case 7: *d++ = *s++;
1.30 + case 6: *d++ = *s++;
1.31 + case 5: *d++ = *s++;
1.32 + case 4: *d++ = *s++;
1.33 + case 3: *d++ = *s++;
1.34 + case 2: *d++ = *s++;
1.35 + case 1: *d++ = *s++;
1.36 + case 0: break;
1.37 + }
1.38 +}
1.39 +
1.40 +static inline void small_memset(void* dst, uint8_t value, int n) {
1.41 + SkASSERT(n > 0 && n <= 15);
1.42 + uint8_t* d = (uint8_t*)dst;
1.43 + switch (n) {
1.44 + case 15: *d++ = value;
1.45 + case 14: *d++ = value;
1.46 + case 13: *d++ = value;
1.47 + case 12: *d++ = value;
1.48 + case 11: *d++ = value;
1.49 + case 10: *d++ = value;
1.50 + case 9: *d++ = value;
1.51 + case 8: *d++ = value;
1.52 + case 7: *d++ = value;
1.53 + case 6: *d++ = value;
1.54 + case 5: *d++ = value;
1.55 + case 4: *d++ = value;
1.56 + case 3: *d++ = value;
1.57 + case 2: *d++ = value;
1.58 + case 1: *d++ = value;
1.59 + case 0: break;
1.60 + }
1.61 +}
1.62 +
1.63 +// can we do better for small counts with our own inlined memcpy/memset?
1.64 +
1.65 +#define PB_MEMSET(addr, value, count) \
1.66 +do { \
1.67 +if ((count) > 15) { \
1.68 +memset(addr, value, count); \
1.69 +} else { \
1.70 +small_memset(addr, value, count); \
1.71 +} \
1.72 +} while (0)
1.73 +
1.74 +#define PB_MEMCPY(dst, src, count) \
1.75 +do { \
1.76 + if ((count) > 15) { \
1.77 + memcpy(dst, src, count); \
1.78 + } else { \
1.79 + small_memcpy(dst, src, count); \
1.80 + } \
1.81 +} while (0)
1.82 +
1.83 +///////////////////////////////////////////////////////////////////////////////
1.84 +
1.85 +#ifdef GATHER_STATS
1.86 + static int gMemSetBuckets[129];
1.87 + static int gMemCpyBuckets[129];
1.88 + static int gCounter;
1.89 +
1.90 +static void register_memset_count(int n) {
1.91 + SkASSERT((unsigned)n <= 128);
1.92 + gMemSetBuckets[n] += 1;
1.93 + gCounter += 1;
1.94 +
1.95 + if ((gCounter & 0xFF) == 0) {
1.96 + SkDebugf("----- packbits memset stats: ");
1.97 + for (size_t i = 0; i < SK_ARRAY_COUNT(gMemSetBuckets); i++) {
1.98 + if (gMemSetBuckets[i]) {
1.99 + SkDebugf(" %d:%d", i, gMemSetBuckets[i]);
1.100 + }
1.101 + }
1.102 + }
1.103 +}
1.104 +static void register_memcpy_count(int n) {
1.105 + SkASSERT((unsigned)n <= 128);
1.106 + gMemCpyBuckets[n] += 1;
1.107 + gCounter += 1;
1.108 +
1.109 + if ((gCounter & 0x1FF) == 0) {
1.110 + SkDebugf("----- packbits memcpy stats: ");
1.111 + for (size_t i = 0; i < SK_ARRAY_COUNT(gMemCpyBuckets); i++) {
1.112 + if (gMemCpyBuckets[i]) {
1.113 + SkDebugf(" %d:%d", i, gMemCpyBuckets[i]);
1.114 + }
1.115 + }
1.116 + }
1.117 +}
1.118 +#else
1.119 +#define register_memset_count(n)
1.120 +#define register_memcpy_count(n)
1.121 +#endif
1.122 +
1.123 +
1.124 +///////////////////////////////////////////////////////////////////////////////
1.125 +
1.126 +size_t SkPackBits::ComputeMaxSize16(int count) {
1.127 + // worst case is the number of 16bit values (times 2) +
1.128 + // 1 byte per (up to) 128 entries.
1.129 + return ((count + 127) >> 7) + (count << 1);
1.130 +}
1.131 +
1.132 +size_t SkPackBits::ComputeMaxSize8(int count) {
1.133 + // worst case is the number of 8bit values + 1 byte per (up to) 128 entries.
1.134 + return ((count + 127) >> 7) + count;
1.135 +}
1.136 +
1.137 +static uint8_t* flush_same16(uint8_t dst[], uint16_t value, int count) {
1.138 + while (count > 0) {
1.139 + int n = count;
1.140 + if (n > 128) {
1.141 + n = 128;
1.142 + }
1.143 + *dst++ = (uint8_t)(n - 1);
1.144 + *dst++ = (uint8_t)(value >> 8);
1.145 + *dst++ = (uint8_t)value;
1.146 + count -= n;
1.147 + }
1.148 + return dst;
1.149 +}
1.150 +
1.151 +static uint8_t* flush_same8(uint8_t dst[], uint8_t value, int count) {
1.152 + while (count > 0) {
1.153 + int n = count;
1.154 + if (n > 128) {
1.155 + n = 128;
1.156 + }
1.157 + *dst++ = (uint8_t)(n - 1);
1.158 + *dst++ = (uint8_t)value;
1.159 + count -= n;
1.160 + }
1.161 + return dst;
1.162 +}
1.163 +
1.164 +static uint8_t* flush_diff16(uint8_t* SK_RESTRICT dst,
1.165 + const uint16_t* SK_RESTRICT src, int count) {
1.166 + while (count > 0) {
1.167 + int n = count;
1.168 + if (n > 128) {
1.169 + n = 128;
1.170 + }
1.171 + *dst++ = (uint8_t)(n + 127);
1.172 + PB_MEMCPY(dst, src, n * sizeof(uint16_t));
1.173 + src += n;
1.174 + dst += n * sizeof(uint16_t);
1.175 + count -= n;
1.176 + }
1.177 + return dst;
1.178 +}
1.179 +
1.180 +static uint8_t* flush_diff8(uint8_t* SK_RESTRICT dst,
1.181 + const uint8_t* SK_RESTRICT src, int count) {
1.182 + while (count > 0) {
1.183 + int n = count;
1.184 + if (n > 128) {
1.185 + n = 128;
1.186 + }
1.187 + *dst++ = (uint8_t)(n + 127);
1.188 + PB_MEMCPY(dst, src, n);
1.189 + src += n;
1.190 + dst += n;
1.191 + count -= n;
1.192 + }
1.193 + return dst;
1.194 +}
1.195 +
1.196 +size_t SkPackBits::Pack16(const uint16_t* SK_RESTRICT src, int count,
1.197 + uint8_t* SK_RESTRICT dst) {
1.198 + uint8_t* origDst = dst;
1.199 + const uint16_t* stop = src + count;
1.200 +
1.201 + for (;;) {
1.202 + count = stop - src;
1.203 + SkASSERT(count >= 0);
1.204 + if (count == 0) {
1.205 + return dst - origDst;
1.206 + }
1.207 + if (1 == count) {
1.208 + *dst++ = 0;
1.209 + *dst++ = (uint8_t)(*src >> 8);
1.210 + *dst++ = (uint8_t)*src;
1.211 + return dst - origDst;
1.212 + }
1.213 +
1.214 + unsigned value = *src;
1.215 + const uint16_t* s = src + 1;
1.216 +
1.217 + if (*s == value) { // accumulate same values...
1.218 + do {
1.219 + s++;
1.220 + if (s == stop) {
1.221 + break;
1.222 + }
1.223 + } while (*s == value);
1.224 + dst = flush_same16(dst, value, s - src);
1.225 + } else { // accumulate diff values...
1.226 + do {
1.227 + if (++s == stop) {
1.228 + goto FLUSH_DIFF;
1.229 + }
1.230 + } while (*s != s[-1]);
1.231 + s -= 1; // back up so we don't grab one of the "same" values that follow
1.232 + FLUSH_DIFF:
1.233 + dst = flush_diff16(dst, src, s - src);
1.234 + }
1.235 + src = s;
1.236 + }
1.237 +}
1.238 +
1.239 +size_t SkPackBits::Pack8(const uint8_t* SK_RESTRICT src, int count,
1.240 + uint8_t* SK_RESTRICT dst) {
1.241 + uint8_t* origDst = dst;
1.242 + const uint8_t* stop = src + count;
1.243 +
1.244 + for (;;) {
1.245 + count = stop - src;
1.246 + SkASSERT(count >= 0);
1.247 + if (count == 0) {
1.248 + return dst - origDst;
1.249 + }
1.250 + if (1 == count) {
1.251 + *dst++ = 0;
1.252 + *dst++ = *src;
1.253 + return dst - origDst;
1.254 + }
1.255 +
1.256 + unsigned value = *src;
1.257 + const uint8_t* s = src + 1;
1.258 +
1.259 + if (*s == value) { // accumulate same values...
1.260 + do {
1.261 + s++;
1.262 + if (s == stop) {
1.263 + break;
1.264 + }
1.265 + } while (*s == value);
1.266 + dst = flush_same8(dst, value, s - src);
1.267 + } else { // accumulate diff values...
1.268 + do {
1.269 + if (++s == stop) {
1.270 + goto FLUSH_DIFF;
1.271 + }
1.272 + // only stop if we hit 3 in a row,
1.273 + // otherwise we get bigger than compuatemax
1.274 + } while (*s != s[-1] || s[-1] != s[-2]);
1.275 + s -= 2; // back up so we don't grab the "same" values that follow
1.276 + FLUSH_DIFF:
1.277 + dst = flush_diff8(dst, src, s - src);
1.278 + }
1.279 + src = s;
1.280 + }
1.281 +}
1.282 +
1.283 +#include "SkUtils.h"
1.284 +
1.285 +int SkPackBits::Unpack16(const uint8_t* SK_RESTRICT src, size_t srcSize,
1.286 + uint16_t* SK_RESTRICT dst) {
1.287 + uint16_t* origDst = dst;
1.288 + const uint8_t* stop = src + srcSize;
1.289 +
1.290 + while (src < stop) {
1.291 + unsigned n = *src++;
1.292 + if (n <= 127) { // repeat count (n + 1)
1.293 + n += 1;
1.294 + sk_memset16(dst, (src[0] << 8) | src[1], n);
1.295 + src += 2;
1.296 + } else { // same count (n - 127)
1.297 + n -= 127;
1.298 + PB_MEMCPY(dst, src, n * sizeof(uint16_t));
1.299 + src += n * sizeof(uint16_t);
1.300 + }
1.301 + dst += n;
1.302 + }
1.303 + SkASSERT(src == stop);
1.304 + return dst - origDst;
1.305 +}
1.306 +
1.307 +int SkPackBits::Unpack8(const uint8_t* SK_RESTRICT src, size_t srcSize,
1.308 + uint8_t* SK_RESTRICT dst) {
1.309 + uint8_t* origDst = dst;
1.310 + const uint8_t* stop = src + srcSize;
1.311 +
1.312 + while (src < stop) {
1.313 + unsigned n = *src++;
1.314 + if (n <= 127) { // repeat count (n + 1)
1.315 + n += 1;
1.316 + PB_MEMSET(dst, *src++, n);
1.317 + } else { // same count (n - 127)
1.318 + n -= 127;
1.319 + PB_MEMCPY(dst, src, n);
1.320 + src += n;
1.321 + }
1.322 + dst += n;
1.323 + }
1.324 + SkASSERT(src == stop);
1.325 + return dst - origDst;
1.326 +}
1.327 +
1.328 +enum UnpackState {
1.329 + CLEAN_STATE,
1.330 + REPEAT_BYTE_STATE,
1.331 + COPY_SRC_STATE
1.332 +};
1.333 +
1.334 +void SkPackBits::Unpack8(uint8_t* SK_RESTRICT dst, size_t dstSkip,
1.335 + size_t dstWrite, const uint8_t* SK_RESTRICT src) {
1.336 + if (dstWrite == 0) {
1.337 + return;
1.338 + }
1.339 +
1.340 + UnpackState state = CLEAN_STATE;
1.341 + size_t stateCount = 0;
1.342 +
1.343 + // state 1: do the skip-loop
1.344 + while (dstSkip > 0) {
1.345 + unsigned n = *src++;
1.346 + if (n <= 127) { // repeat count (n + 1)
1.347 + n += 1;
1.348 + if (n > dstSkip) {
1.349 + state = REPEAT_BYTE_STATE;
1.350 + stateCount = n - dstSkip;
1.351 + n = dstSkip;
1.352 + // we don't increment src here, since its needed in stage 2
1.353 + } else {
1.354 + src++; // skip the src byte
1.355 + }
1.356 + } else { // same count (n - 127)
1.357 + n -= 127;
1.358 + if (n > dstSkip) {
1.359 + state = COPY_SRC_STATE;
1.360 + stateCount = n - dstSkip;
1.361 + n = dstSkip;
1.362 + }
1.363 + src += n;
1.364 + }
1.365 + dstSkip -= n;
1.366 + }
1.367 +
1.368 + // stage 2: perform any catchup from the skip-stage
1.369 + if (stateCount > dstWrite) {
1.370 + stateCount = dstWrite;
1.371 + }
1.372 + switch (state) {
1.373 + case REPEAT_BYTE_STATE:
1.374 + SkASSERT(stateCount > 0);
1.375 + register_memset_count(stateCount);
1.376 + PB_MEMSET(dst, *src++, stateCount);
1.377 + break;
1.378 + case COPY_SRC_STATE:
1.379 + SkASSERT(stateCount > 0);
1.380 + register_memcpy_count(stateCount);
1.381 + PB_MEMCPY(dst, src, stateCount);
1.382 + src += stateCount;
1.383 + break;
1.384 + default:
1.385 + SkASSERT(stateCount == 0);
1.386 + break;
1.387 + }
1.388 + dst += stateCount;
1.389 + dstWrite -= stateCount;
1.390 +
1.391 + // copy at most dstWrite bytes into dst[]
1.392 + while (dstWrite > 0) {
1.393 + unsigned n = *src++;
1.394 + if (n <= 127) { // repeat count (n + 1)
1.395 + n += 1;
1.396 + if (n > dstWrite) {
1.397 + n = dstWrite;
1.398 + }
1.399 + register_memset_count(n);
1.400 + PB_MEMSET(dst, *src++, n);
1.401 + } else { // same count (n - 127)
1.402 + n -= 127;
1.403 + if (n > dstWrite) {
1.404 + n = dstWrite;
1.405 + }
1.406 + register_memcpy_count(n);
1.407 + PB_MEMCPY(dst, src, n);
1.408 + src += n;
1.409 + }
1.410 + dst += n;
1.411 + dstWrite -= n;
1.412 + }
1.413 + SkASSERT(0 == dstWrite);
1.414 +}
