1 /* Copyright 2015 Google Inc. All Rights Reserved. 2 3 Distributed under MIT license. 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT 5 */ 6 7 /* Function for fast encoding of an input fragment, independently from the input 8 history. This function uses two-pass processing: in the first pass we save 9 the found backward matches and literal bytes into a buffer, and in the 10 second pass we emit them into the bit stream using prefix codes built based 11 on the actual command and literal byte histograms. */ 12 13 #ifndef BROTLI_ENC_COMPRESS_FRAGMENT_TWO_PASS_H_ 14 #define BROTLI_ENC_COMPRESS_FRAGMENT_TWO_PASS_H_ 15 16 #include <brotli/types.h> 17 18 #include "../common/constants.h" 19 #include "../common/platform.h" 20 #include "entropy_encode.h" 21 22 #if defined(__cplusplus) || defined(c_plusplus) 23 extern "C" { 24 #endif 25 26 /* TODO(eustas): turn to macro. */ 27 static const size_t kCompressFragmentTwoPassBlockSize = 1 << 17; 28 29 typedef struct BrotliTwoPassArena { 30 uint32_t lit_histo[256]; 31 uint8_t lit_depth[256]; 32 uint16_t lit_bits[256]; 33 34 uint32_t cmd_histo[128]; 35 uint8_t cmd_depth[128]; 36 uint16_t cmd_bits[128]; 37 38 /* BuildAndStoreCommandPrefixCode */ 39 HuffmanTree tmp_tree[2 * BROTLI_NUM_LITERAL_SYMBOLS + 1]; 40 uint8_t tmp_depth[BROTLI_NUM_COMMAND_SYMBOLS]; 41 uint16_t tmp_bits[64]; 42 } BrotliTwoPassArena; 43 44 /* Compresses "input" string to the "*storage" buffer as one or more complete 45 meta-blocks, and updates the "*storage_ix" bit position. 46 47 If "is_last" is 1, emits an additional empty last meta-block. 48 49 REQUIRES: "input_size" is greater than zero, or "is_last" is 1. 50 REQUIRES: "input_size" is less or equal to maximal metablock size (1 << 24). 51 REQUIRES: "command_buf" and "literal_buf" point to at least 52 kCompressFragmentTwoPassBlockSize long arrays. 53 REQUIRES: All elements in "table[0..table_size-1]" are initialized to zero. 54 REQUIRES: "table_size" is a power of two 55 OUTPUT: maximal copy distance <= |input_size| 56 OUTPUT: maximal copy distance <= BROTLI_MAX_BACKWARD_LIMIT(18) */ 57 BROTLI_INTERNAL void BrotliCompressFragmentTwoPass(BrotliTwoPassArena* s, 58 const uint8_t* input, 59 size_t input_size, 60 BROTLI_BOOL is_last, 61 uint32_t* command_buf, 62 uint8_t* literal_buf, 63 int* table, 64 size_t table_size, 65 size_t* storage_ix, 66 uint8_t* storage); 67 68 #if defined(__cplusplus) || defined(c_plusplus) 69 } /* extern "C" */ 70 #endif 71 72 #endif /* BROTLI_ENC_COMPRESS_FRAGMENT_TWO_PASS_H_ */ 73