Mercurial > repos > rliterman > csp2

comparison CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/lzma/vli.h @ 69:33d812a61356

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author jpayne
date Tue, 18 Mar 2025 17:55:14 -0400
parents
children
comparison
equal deleted inserted replaced
67:0e9998148a16 69:33d812a61356
1 /* SPDX-License-Identifier: 0BSD */
2
3 /**
4 * \file lzma/vli.h
5 * \brief Variable-length integer handling
6 * \note Never include this file directly. Use <lzma.h> instead.
7 *
8 * In the .xz format, most integers are encoded in a variable-length
9 * representation, which is sometimes called little endian base-128 encoding.
10 * This saves space when smaller values are more likely than bigger values.
11 *
12 * The encoding scheme encodes seven bits to every byte, using minimum
13 * number of bytes required to represent the given value. Encodings that use
14 * non-minimum number of bytes are invalid, thus every integer has exactly
15 * one encoded representation. The maximum number of bits in a VLI is 63,
16 * thus the vli argument must be less than or equal to UINT64_MAX / 2. You
17 * should use LZMA_VLI_MAX for clarity.
18 */
19
20 /*
21 * Author: Lasse Collin
22 */
23
24 #ifndef LZMA_H_INTERNAL
25 # error Never include this file directly. Use <lzma.h> instead.
26 #endif
27
28
29 /**
30 * \brief Maximum supported value of a variable-length integer
31 */
32 #define LZMA_VLI_MAX (UINT64_MAX / 2)
33
34 /**
35 * \brief VLI value to denote that the value is unknown
36 */
37 #define LZMA_VLI_UNKNOWN UINT64_MAX
38
39 /**
40 * \brief Maximum supported encoded length of variable length integers
41 */
42 #define LZMA_VLI_BYTES_MAX 9
43
44 /**
45 * \brief VLI constant suffix
46 */
47 #define LZMA_VLI_C(n) UINT64_C(n)
48
49
50 /**
51 * \brief Variable-length integer type
52 *
53 * Valid VLI values are in the range [0, LZMA_VLI_MAX]. Unknown value is
54 * indicated with LZMA_VLI_UNKNOWN, which is the maximum value of the
55 * underlying integer type.
56 *
57 * lzma_vli will be uint64_t for the foreseeable future. If a bigger size
58 * is needed in the future, it is guaranteed that 2 * LZMA_VLI_MAX will
59 * not overflow lzma_vli. This simplifies integer overflow detection.
60 */
61 typedef uint64_t lzma_vli;
62
63
64 /**
65 * \brief Validate a variable-length integer
66 *
67 * This is useful to test that application has given acceptable values
68 * for example in the uncompressed_size and compressed_size variables.
69 *
70 * \return True if the integer is representable as a VLI or if it
71 * indicates an unknown value. False otherwise.
72 */
73 #define lzma_vli_is_valid(vli) \
74 ((vli) <= LZMA_VLI_MAX || (vli) == LZMA_VLI_UNKNOWN)
75
76
77 /**
78 * \brief Encode a variable-length integer
79 *
80 * This function has two modes: single-call and multi-call. Single-call mode
81 * encodes the whole integer at once; it is an error if the output buffer is
82 * too small. Multi-call mode saves the position in *vli_pos, and thus it is
83 * possible to continue encoding if the buffer becomes full before the whole
84 * integer has been encoded.
85 *
86 * \param vli Integer to be encoded
87 * \param[out] vli_pos How many VLI-encoded bytes have already been written
88 * out. When starting to encode a new integer in
89 * multi-call mode, *vli_pos must be set to zero.
90 * To use single-call encoding, set vli_pos to NULL.
91 * \param[out] out Beginning of the output buffer
92 * \param[out] out_pos The next byte will be written to out[*out_pos].
93 * \param out_size Size of the out buffer; the first byte into
94 * which no data is written to is out[out_size].
95 *
96 * \return Slightly different return values are used in multi-call and
97 * single-call modes.
98 *
99 * Single-call (vli_pos == NULL):
100 * - LZMA_OK: Integer successfully encoded.
101 * - LZMA_PROG_ERROR: Arguments are not sane. This can be due
102 * to too little output space; single-call mode doesn't use
103 * LZMA_BUF_ERROR, since the application should have checked
104 * the encoded size with lzma_vli_size().
105 *
106 * Multi-call (vli_pos != NULL):
107 * - LZMA_OK: So far all OK, but the integer is not
108 * completely written out yet.
109 * - LZMA_STREAM_END: Integer successfully encoded.
110 * - LZMA_BUF_ERROR: No output space was provided.
111 * - LZMA_PROG_ERROR: Arguments are not sane.
112 */
113 extern LZMA_API(lzma_ret) lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
114 uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow;
115
116
117 /**
118 * \brief Decode a variable-length integer
119 *
120 * Like lzma_vli_encode(), this function has single-call and multi-call modes.
121 *
122 * \param[out] vli Pointer to decoded integer. The decoder will
123 * initialize it to zero when *vli_pos == 0, so
124 * application isn't required to initialize *vli.
125 * \param[out] vli_pos How many bytes have already been decoded. When
126 * starting to decode a new integer in multi-call
127 * mode, *vli_pos must be initialized to zero. To
128 * use single-call decoding, set vli_pos to NULL.
129 * \param in Beginning of the input buffer
130 * \param[out] in_pos The next byte will be read from in[*in_pos].
131 * \param in_size Size of the input buffer; the first byte that
132 * won't be read is in[in_size].
133 *
134 * \return Slightly different return values are used in multi-call and
135 * single-call modes.
136 *
137 * Single-call (vli_pos == NULL):
138 * - LZMA_OK: Integer successfully decoded.
139 * - LZMA_DATA_ERROR: Integer is corrupt. This includes hitting
140 * the end of the input buffer before the whole integer was
141 * decoded; providing no input at all will use LZMA_DATA_ERROR.
142 * - LZMA_PROG_ERROR: Arguments are not sane.
143 *
144 * Multi-call (vli_pos != NULL):
145 * - LZMA_OK: So far all OK, but the integer is not
146 * completely decoded yet.
147 * - LZMA_STREAM_END: Integer successfully decoded.
148 * - LZMA_DATA_ERROR: Integer is corrupt.
149 * - LZMA_BUF_ERROR: No input was provided.
150 * - LZMA_PROG_ERROR: Arguments are not sane.
151 */
152 extern LZMA_API(lzma_ret) lzma_vli_decode(lzma_vli *vli, size_t *vli_pos,
153 const uint8_t *in, size_t *in_pos, size_t in_size)
154 lzma_nothrow;
155
156
157 /**
158 * \brief Get the number of bytes required to encode a VLI
159 *
160 * \param vli Integer whose encoded size is to be determined
161 *
162 * \return Number of bytes on success (1-9). If vli isn't valid,
163 * zero is returned.
164 */
165 extern LZMA_API(uint32_t) lzma_vli_size(lzma_vli vli)
166 lzma_nothrow lzma_attr_pure;