delta_decoder.c revision 292588
1114402Sru/////////////////////////////////////////////////////////////////////////////// 2114402Sru// 3114402Sru/// \file delta_decoder.c 4114402Sru/// \brief Delta filter decoder 5114402Sru// 6114402Sru// Author: Lasse Collin 7114402Sru// 8114402Sru// This file has been put into the public domain. 9114402Sru// You can do whatever you want with this file. 10114402Sru// 11114402Sru/////////////////////////////////////////////////////////////////////////////// 12114402Sru 13114402Sru#include "delta_decoder.h" 14114402Sru#include "delta_private.h" 15114402Sru 16114402Sru 17114402Srustatic void 18151503Srudecode_buffer(lzma_coder *coder, uint8_t *buffer, size_t size) 19114402Sru{ 20114411Sru const size_t distance = coder->distance; 21114411Sru 22114402Sru for (size_t i = 0; i < size; ++i) { 23114402Sru buffer[i] += coder->history[(distance + coder->pos) & 0xFF]; 24114402Sru coder->history[coder->pos-- & 0xFF] = buffer[i]; 25114402Sru } 26114402Sru} 27114402Sru 28114402Sru 29114402Srustatic lzma_ret 30114402Srudelta_decode(lzma_coder *coder, const lzma_allocator *allocator, 31114402Sru const uint8_t *restrict in, size_t *restrict in_pos, 32114402Sru size_t in_size, uint8_t *restrict out, 33114402Sru size_t *restrict out_pos, size_t out_size, lzma_action action) 34114402Sru{ 35114402Sru assert(coder->next.code != NULL); 36114411Sru 37114402Sru const size_t out_start = *out_pos; 38114402Sru 39114402Sru const lzma_ret ret = coder->next.code(coder->next.coder, allocator, 40114402Sru in, in_pos, in_size, out, out_pos, out_size, 41114402Sru action); 42114402Sru 43114411Sru decode_buffer(coder, out + out_start, *out_pos - out_start); 44114402Sru 45114402Sru return ret; 46114402Sru} 47114402Sru 48114402Sru 49114402Sruextern lzma_ret 50114402Srulzma_delta_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, 51114402Sru const lzma_filter_info *filters) 52114402Sru{ 53114402Sru next->code = &delta_decode; 54114402Sru return lzma_delta_coder_init(next, allocator, filters); 55114402Sru} 56114402Sru 57114402Sru 58114402Sruextern lzma_ret 59114402Srulzma_delta_props_decode(void **options, const lzma_allocator *allocator, 60114402Sru const uint8_t *props, size_t props_size) 61114402Sru{ 62114402Sru if (props_size != 1) 63 return LZMA_OPTIONS_ERROR; 64 65 lzma_options_delta *opt 66 = lzma_alloc(sizeof(lzma_options_delta), allocator); 67 if (opt == NULL) 68 return LZMA_MEM_ERROR; 69 70 opt->type = LZMA_DELTA_TYPE_BYTE; 71 opt->dist = props[0] + 1; 72 73 *options = opt; 74 75 return LZMA_OK; 76} 77