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

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