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
delta_coder_end(void * coder_ptr,const lzma_allocator * allocator)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
lzma_delta_coder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters)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
lzma_delta_coder_memusage(const void * options)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