1207753Smm/////////////////////////////////////////////////////////////////////////////// 2207753Smm// 3207753Smm/// \file delta_common.c 4207753Smm/// \brief Common stuff for Delta encoder and decoder 5207753Smm// 6207753Smm// Author: Lasse Collin 7207753Smm// 8207753Smm// This file has been put into the public domain. 9207753Smm// You can do whatever you want with this file. 10207753Smm// 11207753Smm/////////////////////////////////////////////////////////////////////////////// 12207753Smm 13207753Smm#include "delta_common.h" 14207753Smm#include "delta_private.h" 15207753Smm 16207753Smm 17207753Smmstatic void 18292588Sdelphijdelta_coder_end(lzma_coder *coder, const lzma_allocator *allocator) 19207753Smm{ 20207753Smm lzma_next_end(&coder->next, allocator); 21207753Smm lzma_free(coder, allocator); 22207753Smm return; 23207753Smm} 24207753Smm 25207753Smm 26207753Smmextern lzma_ret 27292588Sdelphijlzma_delta_coder_init(lzma_next_coder *next, const lzma_allocator *allocator, 28207753Smm const lzma_filter_info *filters) 29207753Smm{ 30207753Smm // Allocate memory for the decoder if needed. 31207753Smm if (next->coder == NULL) { 32207753Smm next->coder = lzma_alloc(sizeof(lzma_coder), allocator); 33207753Smm if (next->coder == NULL) 34207753Smm return LZMA_MEM_ERROR; 35207753Smm 36207753Smm // End function is the same for encoder and decoder. 37207753Smm next->end = &delta_coder_end; 38207753Smm next->coder->next = LZMA_NEXT_CODER_INIT; 39207753Smm } 40207753Smm 41207753Smm // Validate the options. 42207753Smm if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX) 43207753Smm return LZMA_OPTIONS_ERROR; 44207753Smm 45207753Smm // Set the delta distance. 46207753Smm const lzma_options_delta *opt = filters[0].options; 47207753Smm next->coder->distance = opt->dist; 48207753Smm 49207753Smm // Initialize the rest of the variables. 50207753Smm next->coder->pos = 0; 51207753Smm memzero(next->coder->history, LZMA_DELTA_DIST_MAX); 52207753Smm 53207753Smm // Initialize the next decoder in the chain, if any. 54207753Smm return lzma_next_filter_init(&next->coder->next, 55207753Smm allocator, filters + 1); 56207753Smm} 57207753Smm 58207753Smm 59207753Smmextern uint64_t 60207753Smmlzma_delta_coder_memusage(const void *options) 61207753Smm{ 62207753Smm const lzma_options_delta *opt = options; 63207753Smm 64207753Smm if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE 65207753Smm || opt->dist < LZMA_DELTA_DIST_MIN 66207753Smm || opt->dist > LZMA_DELTA_DIST_MAX) 67207753Smm return UINT64_MAX; 68207753Smm 69207753Smm return sizeof(lzma_coder); 70207753Smm} 71