1 // SPDX-License-Identifier: 0BSD 2 3 /////////////////////////////////////////////////////////////////////////////// 4 // 5 /// \file delta_common.c 6 /// \brief Common stuff for Delta encoder and decoder 7 // 8 // Author: Lasse Collin 9 // 10 /////////////////////////////////////////////////////////////////////////////// 11 12 #include "delta_common.h" 13 #include "delta_private.h" 14 15 16 static void 17 delta_coder_end(void *coder_ptr, const lzma_allocator *allocator) 18 { 19 lzma_delta_coder *coder = coder_ptr; 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 lzma_delta_coder *coder = next->coder; 32 if (coder == NULL) { 33 coder = lzma_alloc(sizeof(lzma_delta_coder), allocator); 34 if (coder == NULL) 35 return LZMA_MEM_ERROR; 36 37 next->coder = coder; 38 39 // End function is the same for encoder and decoder. 40 next->end = &delta_coder_end; 41 coder->next = LZMA_NEXT_CODER_INIT; 42 } 43 44 // Validate the options. 45 if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX) 46 return LZMA_OPTIONS_ERROR; 47 48 // Set the delta distance. 49 const lzma_options_delta *opt = filters[0].options; 50 coder->distance = opt->dist; 51 52 // Initialize the rest of the variables. 53 coder->pos = 0; 54 memzero(coder->history, LZMA_DELTA_DIST_MAX); 55 56 // Initialize the next decoder in the chain, if any. 57 return lzma_next_filter_init(&coder->next, allocator, filters + 1); 58 } 59 60 61 extern uint64_t 62 lzma_delta_coder_memusage(const void *options) 63 { 64 const lzma_options_delta *opt = options; 65 66 if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE 67 || opt->dist < LZMA_DELTA_DIST_MIN 68 || opt->dist > LZMA_DELTA_DIST_MAX) 69 return UINT64_MAX; 70 71 return sizeof(lzma_delta_coder); 72 } 73