| 210 | } |
| 211 | |
| 212 | uint32 Extend(uint32 crc, const char *buf, size_t size) { |
| 213 | static bool can_accelerate = CanAccelerate(); |
| 214 | if (can_accelerate) { |
| 215 | return AcceleratedExtend(crc, buf, size); |
| 216 | } |
| 217 | |
| 218 | const uint8 *p = reinterpret_cast<const uint8 *>(buf); |
| 219 | const uint8 *e = p + size; |
| 220 | uint32 l = crc ^ 0xffffffffu; |
| 221 | |
| 222 | #define STEP1 \ |
| 223 | do { \ |
| 224 | int c = (l & 0xff) ^ *p++; \ |
| 225 | l = table0_[c] ^ (l >> 8); \ |
| 226 | } while (0) |
| 227 | |
| 228 | #define STEP4 \ |
| 229 | do { \ |
| 230 | uint32 c = l ^ LE_LOAD32(p); \ |
| 231 | p += 4; \ |
| 232 | l = table3_[c & 0xff] ^ table2_[(c >> 8) & 0xff] ^ \ |
| 233 | table1_[(c >> 16) & 0xff] ^ table0_[c >> 24]; \ |
| 234 | } while (0) |
| 235 | |
| 236 | // Point x at first 4-byte aligned byte in string. This might be |
| 237 | // just past the end of the string. |
| 238 | const uintptr_t pval = reinterpret_cast<uintptr_t>(p); |
| 239 | const uint8 *x = reinterpret_cast<const uint8 *>(((pval + 3) >> 2) << 2); |
| 240 | if (x <= e) { |
| 241 | // Process bytes until finished or p is 4-byte aligned |
| 242 | while (p != x) { |
| 243 | STEP1; |
| 244 | } |
| 245 | } |
| 246 | // Process bytes 16 at a time |
| 247 | while ((e - p) >= 16) { |
| 248 | STEP4; |
| 249 | STEP4; |
| 250 | STEP4; |
| 251 | STEP4; |
| 252 | } |
| 253 | // Process bytes 4 at a time |
| 254 | while ((e - p) >= 4) { |
| 255 | STEP4; |
| 256 | } |
| 257 | // Process the last few bytes |
| 258 | while (p != e) { |
| 259 | STEP1; |
| 260 | } |
| 261 | #undef STEP4 |
| 262 | #undef STEP1 |
| 263 | return l ^ 0xffffffffu; |
| 264 | } |
| 265 | |
| 266 | #if defined(PLATFORM_GOOGLE) |
| 267 | uint32 Extend(uint32 crc, const absl::Cord &cord) { |