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(void *coder_ptr, const lzma_allocator *allocator) 19 { 20 lzma_delta_coder *coder = coder_ptr; 21 lzma_next_end(&coder->next, allocator); 22 lzma_free(coder, allocator); 23 return; 24 } 25 26 27 extern lzma_ret 28 lzma_delta_coder_init(lzma_next_coder *next, const lzma_allocator *allocator, 29 const lzma_filter_info *filters) 30 { 31 // Allocate memory for the decoder if needed. 32 lzma_delta_coder *coder = next->coder; 33 if (coder == NULL) { 34 coder = lzma_alloc(sizeof(lzma_delta_coder), allocator); 35 if (coder == NULL) 36 return LZMA_MEM_ERROR; 37 38 next->coder = coder; 39 40 // End function is the same for encoder and decoder. 41 next->end = &delta_coder_end; 42 coder->next = LZMA_NEXT_CODER_INIT; 43 } 44 45 // Validate the options. 46 if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX) 47 return LZMA_OPTIONS_ERROR; 48 49 // Set the delta distance. 50 const lzma_options_delta *opt = filters[0].options; 51 coder->distance = opt->dist; 52 53 // Initialize the rest of the variables. 54 coder->pos = 0; 55 memzero(coder->history, LZMA_DELTA_DIST_MAX); 56 57 // Initialize the next decoder in the chain, if any. 58 return lzma_next_filter_init(&coder->next, allocator, filters + 1); 59 } 60 61 62 extern uint64_t 63 lzma_delta_coder_memusage(const void *options) 64 { 65 const lzma_options_delta *opt = options; 66 67 if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE 68 || opt->dist < LZMA_DELTA_DIST_MIN 69 || opt->dist > LZMA_DELTA_DIST_MAX) 70 return UINT64_MAX; 71 72 return sizeof(lzma_delta_coder); 73 } 74