1/**
2 * \file lzma/delta.h
3 * \brief Delta filter
4 */
5
6/*
7 * Author: Lasse Collin
8 *
9 * This file has been put into the public domain.
10 * You can do whatever you want with this file.
11 *
12 * See ../lzma.h for information about liblzma as a whole.
13 */
14
15#ifndef LZMA_H_INTERNAL
16# error Never include this file directly. Use <lzma.h> instead.
17#endif
18
19
20/**
21 * \brief Filter ID
22 *
23 * Filter ID of the Delta filter. This is used as lzma_filter.id.
24 */
25#define LZMA_FILTER_DELTA LZMA_VLI_C(0x03)
26
27
28/**
29 * \brief Type of the delta calculation
30 *
31 * Currently only byte-wise delta is supported. Other possible types could
32 * be, for example, delta of 16/32/64-bit little/big endian integers, but
33 * these are not currently planned since byte-wise delta is almost as good.
34 */
35typedef enum {
36 LZMA_DELTA_TYPE_BYTE
37} lzma_delta_type;
38
39
40/**
41 * \brief Options for the Delta filter
42 *
43 * These options are needed by both encoder and decoder.
44 */
45typedef struct {
46 /** For now, this must always be LZMA_DELTA_TYPE_BYTE. */
47 lzma_delta_type type;
48
49 /**
50 * \brief Delta distance
51 *
52 * With the only currently supported type, LZMA_DELTA_TYPE_BYTE,
53 * the distance is as bytes.
54 *
55 * Examples:
56 * - 16-bit stereo audio: distance = 4 bytes
57 * - 24-bit RGB image data: distance = 3 bytes
58 */
59 uint32_t dist;
60# define LZMA_DELTA_DIST_MIN 1
61# define LZMA_DELTA_DIST_MAX 256
62
63 /*
64 * Reserved space to allow possible future extensions without
65 * breaking the ABI. You should not touch these, because the names
66 * of these variables may change. These are and will never be used
67 * when type is LZMA_DELTA_TYPE_BYTE, so it is safe to leave these
68 * uninitialized.
69 */
70 uint32_t reserved_int1;
71 uint32_t reserved_int2;
72 uint32_t reserved_int3;
73 uint32_t reserved_int4;
74 void *reserved_ptr1;
75 void *reserved_ptr2;
76
77} lzma_options_delta;
78

source code of include/lzma/delta.h