1 // SPDX-License-Identifier: 0BSD 2 3 /////////////////////////////////////////////////////////////////////////////// 4 // 5 /// \file delta_decoder.c 6 /// \brief Delta filter decoder 7 // 8 // Author: Lasse Collin 9 // 10 /////////////////////////////////////////////////////////////////////////////// 11 12 #include "delta_decoder.h" 13 #include "delta_private.h" 14 15 16 static void 17 decode_buffer(lzma_delta_coder *coder, uint8_t *buffer, size_t size) 18 { 19 const size_t distance = coder->distance; 20 21 for (size_t i = 0; i < size; ++i) { 22 buffer[i] += coder->history[(distance + coder->pos) & 0xFF]; 23 coder->history[coder->pos-- & 0xFF] = buffer[i]; 24 } 25 } 26 27 28 // For an unknown reason NVIDIA HPC Compiler needs this pragma 29 // to produce working code. 30 #ifdef __NVCOMPILER 31 # pragma routine novector 32 #endif 33 static lzma_ret 34 delta_decode(void *coder_ptr, const lzma_allocator *allocator, 35 const uint8_t *restrict in, size_t *restrict in_pos, 36 size_t in_size, uint8_t *restrict out, 37 size_t *restrict out_pos, size_t out_size, lzma_action action) 38 { 39 lzma_delta_coder *coder = coder_ptr; 40 41 assert(coder->next.code != NULL); 42 43 const size_t out_start = *out_pos; 44 45 const lzma_ret ret = coder->next.code(coder->next.coder, allocator, 46 in, in_pos, in_size, out, out_pos, out_size, 47 action); 48 49 // out might be NULL. In that case size == 0. Null pointer + 0 is 50 // undefined behavior so skip the call in that case as it would 51 // do nothing anyway. 52 const size_t size = *out_pos - out_start; 53 if (size > 0) 54 decode_buffer(coder, out + out_start, size); 55 56 return ret; 57 } 58 59 60 extern lzma_ret 61 lzma_delta_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, 62 const lzma_filter_info *filters) 63 { 64 next->code = &delta_decode; 65 return lzma_delta_coder_init(next, allocator, filters); 66 } 67 68 69 extern lzma_ret 70 lzma_delta_props_decode(void **options, const lzma_allocator *allocator, 71 const uint8_t *props, size_t props_size) 72 { 73 if (props_size != 1) 74 return LZMA_OPTIONS_ERROR; 75 76 lzma_options_delta *opt 77 = lzma_alloc(sizeof(lzma_options_delta), allocator); 78 if (opt == NULL) 79 return LZMA_MEM_ERROR; 80 81 opt->type = LZMA_DELTA_TYPE_BYTE; 82 opt->dist = props[0] + 1U; 83 84 *options = opt; 85 86 return LZMA_OK; 87 } 88