1 ///////////////////////////////////////////////////////////////////////////////
3 /// \file delta_encoder.c
4 /// \brief Delta filter encoder
6 // Author: Lasse Collin
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
11 ///////////////////////////////////////////////////////////////////////////////
13 #include "delta_encoder.h"
14 #include "delta_private.h"
17 /// Copies and encodes the data at the same time. This is used when Delta
18 /// is the first filter in the chain (and thus the last filter in the
19 /// encoder's filter stack).
21 copy_and_encode(lzma_coder *coder,
22 const uint8_t *restrict in, uint8_t *restrict out, size_t size)
24 const size_t distance = coder->distance;
27 for (i = 0; i < size; ++i) {
28 const uint8_t tmp = coder->history[
29 (distance + coder->pos) & 0xFF];
30 coder->history[coder->pos-- & 0xFF] = in[i];
36 /// Encodes the data in place. This is used when we are the last filter
37 /// in the chain (and thus non-last filter in the encoder's filter stack).
39 encode_in_place(lzma_coder *coder, uint8_t *buffer, size_t size)
41 const size_t distance = coder->distance;
44 for (i = 0; i < size; ++i) {
45 const uint8_t tmp = coder->history[
46 (distance + coder->pos) & 0xFF];
47 coder->history[coder->pos-- & 0xFF] = buffer[i];
54 delta_encode(lzma_coder *coder, lzma_allocator *allocator,
55 const uint8_t *restrict in, size_t *restrict in_pos,
56 size_t in_size, uint8_t *restrict out,
57 size_t *restrict out_pos, size_t out_size, lzma_action action)
61 if (coder->next.code == NULL) {
62 const size_t in_avail = in_size - *in_pos;
63 const size_t out_avail = out_size - *out_pos;
64 const size_t size = my_min(in_avail, out_avail);
66 copy_and_encode(coder, in + *in_pos, out + *out_pos, size);
71 ret = action != LZMA_RUN && *in_pos == in_size
72 ? LZMA_STREAM_END : LZMA_OK;
75 const size_t out_start = *out_pos;
77 ret = coder->next.code(coder->next.coder, allocator,
78 in, in_pos, in_size, out, out_pos, out_size,
81 encode_in_place(coder, out + out_start, *out_pos - out_start);
89 delta_encoder_update(lzma_coder *coder, lzma_allocator *allocator,
90 const lzma_filter *filters_null lzma_attribute((unused)),
91 const lzma_filter *reversed_filters)
93 // Delta doesn't and will never support changing the options in
94 // the middle of encoding. If the app tries to change them, we
95 // simply ignore them.
96 return lzma_next_filter_update(
97 &coder->next, allocator, reversed_filters + 1);
102 lzma_delta_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
103 const lzma_filter_info *filters)
105 next->code = &delta_encode;
106 next->update = &delta_encoder_update;
107 return lzma_delta_coder_init(next, allocator, filters);
112 lzma_delta_props_encode(const void *options, uint8_t *out)
114 // The caller must have already validated the options, so it's
115 // LZMA_PROG_ERROR if they are invalid.
116 if (lzma_delta_coder_memusage(options) == UINT64_MAX)
117 return LZMA_PROG_ERROR;
119 const lzma_options_delta *opt = options;
120 out[0] = opt->dist - LZMA_DELTA_DIST_MIN;