1/////////////////////////////////////////////////////////////////////////////// 2// 3/// \file delta_decoder.c 4/// \brief Delta filter decoder 5// 6// Author: Lasse Collin 7// 8// This file has been put into the public domain. 9// You can do whatever you want with this file. 10// 11/////////////////////////////////////////////////////////////////////////////// 12 13#include "delta_decoder.h" 14#include "delta_private.h" 15 16 17static void 18decode_buffer(lzma_delta_coder *coder, uint8_t *buffer, size_t size) 19{ 20 const size_t distance = coder->distance; 21 22 for (size_t i = 0; i < size; ++i) { 23 buffer[i] += coder->history[(distance + coder->pos) & 0xFF]; 24 coder->history[coder->pos-- & 0xFF] = buffer[i]; 25 } 26} 27 28 29static lzma_ret 30delta_decode(void *coder_ptr, const lzma_allocator *allocator, 31 const uint8_t *restrict in, size_t *restrict in_pos, 32 size_t in_size, uint8_t *restrict out, 33 size_t *restrict out_pos, size_t out_size, lzma_action action) 34{ 35 lzma_delta_coder *coder = coder_ptr; 36 37 assert(coder->next.code != NULL); 38 39 const size_t out_start = *out_pos; 40 41 const lzma_ret ret = coder->next.code(coder->next.coder, allocator, 42 in, in_pos, in_size, out, out_pos, out_size, 43 action); 44 45 decode_buffer(coder, out + out_start, *out_pos - out_start); 46 47 return ret; 48} 49 50 51extern lzma_ret 52lzma_delta_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, 53 const lzma_filter_info *filters) 54{ 55 next->code = &delta_decode; 56 return lzma_delta_coder_init(next, allocator, filters); 57} 58 59 60extern lzma_ret 61lzma_delta_props_decode(void **options, const lzma_allocator *allocator, 62 const uint8_t *props, size_t props_size) 63{ 64 if (props_size != 1) 65 return LZMA_OPTIONS_ERROR; 66 67 lzma_options_delta *opt 68 = lzma_alloc(sizeof(lzma_options_delta), allocator); 69 if (opt == NULL) 70 return LZMA_MEM_ERROR; 71 72 opt->type = LZMA_DELTA_TYPE_BYTE; 73 opt->dist = props[0] + 1; 74 75 *options = opt; 76 77 return LZMA_OK; 78} 79