1 /////////////////////////////////////////////////////////////////////////////// 2 // 3 /// \file delta_common.c 4 /// \brief Common stuff for Delta encoder and 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_common.h" 14 #include "delta_private.h" 15 16 17 static void 18 delta_coder_end(lzma_coder *coder, const lzma_allocator *allocator) 19 { 20 lzma_next_end(&coder->next, allocator); 21 lzma_free(coder, allocator); 22 return; 23 } 24 25 26 extern lzma_ret 27 lzma_delta_coder_init(lzma_next_coder *next, const lzma_allocator *allocator, 28 const lzma_filter_info *filters) 29 { 30 // Allocate memory for the decoder if needed. 31 if (next->coder == NULL) { 32 next->coder = lzma_alloc(sizeof(lzma_coder), allocator); 33 if (next->coder == NULL) 34 return LZMA_MEM_ERROR; 35 36 // End function is the same for encoder and decoder. 37 next->end = &delta_coder_end; 38 next->coder->next = LZMA_NEXT_CODER_INIT; 39 } 40 41 // Validate the options. 42 if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX) 43 return LZMA_OPTIONS_ERROR; 44 45 // Set the delta distance. 46 const lzma_options_delta *opt = filters[0].options; 47 next->coder->distance = opt->dist; 48 49 // Initialize the rest of the variables. 50 next->coder->pos = 0; 51 memzero(next->coder->history, LZMA_DELTA_DIST_MAX); 52 53 // Initialize the next decoder in the chain, if any. 54 return lzma_next_filter_init(&next->coder->next, 55 allocator, filters + 1); 56 } 57 58 59 extern uint64_t 60 lzma_delta_coder_memusage(const void *options) 61 { 62 const lzma_options_delta *opt = options; 63 64 if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE 65 || opt->dist < LZMA_DELTA_DIST_MIN 66 || opt->dist > LZMA_DELTA_DIST_MAX) 67 return UINT64_MAX; 68 69 return sizeof(lzma_coder); 70 } 71