projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 11b7501a SB |
1 | /* Copyright 2013 Google Inc. All Rights Reserved.\r |
| 2 | \r | |
| 3 | Distributed under MIT license.\r | |
| 4 | See file LICENSE for detail or copy at https://opensource.org/licenses/MIT\r | |
| 5 | */\r | |
| 6 | \r | |
| 7 | /* Functions for encoding of integers into prefix codes the amount of extra\r | |
| 8 | bits, and the actual values of the extra bits. */\r | |
| 9 | \r | |
| 10 | #ifndef BROTLI_ENC_PREFIX_H_\r | |
| 11 | #define BROTLI_ENC_PREFIX_H_\r | |
| 12 | \r | |
| 13 | #include "../common/constants.h"\r | |
| 14 | #include "../common/port.h"\r | |
| 15 | #include "../common/types.h"\r | |
| 16 | #include "./fast_log.h"\r | |
| 17 | \r | |
| 18 | #if defined(__cplusplus) || defined(c_plusplus)\r | |
| 19 | extern "C" {\r | |
| 20 | #endif\r | |
| 21 | \r | |
| 22 | static BROTLI_INLINE void PrefixEncodeCopyDistance(size_t distance_code,\r | |
| 23 | size_t num_direct_codes,\r | |
| 24 | size_t postfix_bits,\r | |
| 25 | uint16_t* code,\r | |
| 26 | uint32_t* extra_bits) {\r | |
| 27 | if (distance_code < BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_codes) {\r | |
| 28 | *code = (uint16_t)distance_code;\r | |
| 29 | *extra_bits = 0;\r | |
| 30 | return;\r | |
| 31 | } else {\r | |
| 32 | size_t dist = ((size_t)1 << (postfix_bits + 2u)) +\r | |
| 33 | (distance_code - BROTLI_NUM_DISTANCE_SHORT_CODES - num_direct_codes);\r | |
| 34 | size_t bucket = Log2FloorNonZero(dist) - 1;\r | |
| 35 | size_t postfix_mask = (1u << postfix_bits) - 1;\r | |
| 36 | size_t postfix = dist & postfix_mask;\r | |
| 37 | size_t prefix = (dist >> bucket) & 1;\r | |
| 38 | size_t offset = (2 + prefix) << bucket;\r | |
| 39 | size_t nbits = bucket - postfix_bits;\r | |
| 40 | *code = (uint16_t)(\r | |
| 41 | (BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_codes +\r | |
| 42 | ((2 * (nbits - 1) + prefix) << postfix_bits) + postfix));\r | |
| 43 | *extra_bits = (uint32_t)(\r | |
| 44 | (nbits << 24) | ((dist - offset) >> postfix_bits));\r | |
| 45 | }\r | |
| 46 | }\r | |
| 47 | \r | |
| 48 | #if defined(__cplusplus) || defined(c_plusplus)\r | |
| 49 | } /* extern "C" */\r | |
| 50 | #endif\r | |
| 51 | \r | |
| 52 | #endif /* BROTLI_ENC_PREFIX_H_ */\r |