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 /* SPDX-License-Identifier: 0BSD */
 
 /**
  * \file        lzma/vli.h
  * \brief       Variable-length integer handling
  * \note        Never include this file directly. Use <lzma.h> instead.
  *
  * In the .xz format, most integers are encoded in a variable-length
  * representation, which is sometimes called little endian base-128 encoding.
  * This saves space when smaller values are more likely than bigger values.
  *
  * The encoding scheme encodes seven bits to every byte, using minimum
  * number of bytes required to represent the given value. Encodings that use
  * non-minimum number of bytes are invalid, thus every integer has exactly
  * one encoded representation. The maximum number of bits in a VLI is 63,
  * thus the vli argument must be less than or equal to UINT64_MAX / 2. You
  * should use LZMA_VLI_MAX for clarity.
  */
 
 /*
  * Author: Lasse Collin
  */
 
 #ifndef LZMA_H_INTERNAL
 #   error Never include this file directly. Use <lzma.h> instead.
 #endif
 
 
 /**
  * \brief       Maximum supported value of a variable-length integer
  */
 #define LZMA_VLI_MAX (UINT64_MAX / 2)
 
 /**
  * \brief       VLI value to denote that the value is unknown
  */
 #define LZMA_VLI_UNKNOWN UINT64_MAX
 
 /**
  * \brief       Maximum supported encoded length of variable length integers
  */
 #define LZMA_VLI_BYTES_MAX 9
 
 /**
  * \brief       VLI constant suffix
  */
 #define LZMA_VLI_C(n) UINT64_C(n)
 
 
 /**
  * \brief       Variable-length integer type
  *
  * Valid VLI values are in the range [0, LZMA_VLI_MAX]. Unknown value is
  * indicated with LZMA_VLI_UNKNOWN, which is the maximum value of the
  * underlying integer type.
  *
  * lzma_vli will be uint64_t for the foreseeable future. If a bigger size
  * is needed in the future, it is guaranteed that 2 * LZMA_VLI_MAX will
  * not overflow lzma_vli. This simplifies integer overflow detection.
  */
 typedef uint64_t lzma_vli;
 
 
 /**
  * \brief       Validate a variable-length integer
  *
  * This is useful to test that application has given acceptable values
  * for example in the uncompressed_size and compressed_size variables.
  *
  * \return      True if the integer is representable as a VLI or if it
  *              indicates an unknown value. False otherwise.
  */
 #define lzma_vli_is_valid(vli) \
     ((vli) <= LZMA_VLI_MAX || (vli) == LZMA_VLI_UNKNOWN)
 
 
 /**
  * \brief       Encode a variable-length integer
  *
  * This function has two modes: single-call and multi-call. Single-call mode
  * encodes the whole integer at once; it is an error if the output buffer is
  * too small. Multi-call mode saves the position in *vli_pos, and thus it is
  * possible to continue encoding if the buffer becomes full before the whole
  * integer has been encoded.
  *
  * \param       vli       Integer to be encoded
  * \param[out]  vli_pos   How many VLI-encoded bytes have already been written
  *                        out. When starting to encode a new integer in
  *                        multi-call mode, *vli_pos must be set to zero.
  *                        To use single-call encoding, set vli_pos to NULL.
  * \param[out]  out       Beginning of the output buffer
  * \param[out]  out_pos   The next byte will be written to out[*out_pos].
  * \param       out_size  Size of the out buffer; the first byte into
  *                        which no data is written to is out[out_size].
  *
  * \return      Slightly different return values are used in multi-call and
  *              single-call modes.
  *
  *              Single-call (vli_pos == NULL):
  *              - LZMA_OK: Integer successfully encoded.
  *              - LZMA_PROG_ERROR: Arguments are not sane. This can be due
  *                to too little output space; single-call mode doesn't use
  *                LZMA_BUF_ERROR, since the application should have checked
  *                the encoded size with lzma_vli_size().
  *
  *              Multi-call (vli_pos != NULL):
  *              - LZMA_OK: So far all OK, but the integer is not
  *                completely written out yet.
  *              - LZMA_STREAM_END: Integer successfully encoded.
  *              - LZMA_BUF_ERROR: No output space was provided.
  *              - LZMA_PROG_ERROR: Arguments are not sane.
  */
 extern LZMA_API(lzma_ret) lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
         uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow;
 
 
 /**
  * \brief       Decode a variable-length integer
  *
  * Like lzma_vli_encode(), this function has single-call and multi-call modes.
  *
  * \param[out]  vli       Pointer to decoded integer. The decoder will
  *                        initialize it to zero when *vli_pos == 0, so
  *                        application isn't required to initialize *vli.
  * \param[out]  vli_pos   How many bytes have already been decoded. When
  *                        starting to decode a new integer in multi-call
  *                        mode, *vli_pos must be initialized to zero. To
  *                        use single-call decoding, set vli_pos to NULL.
  * \param       in        Beginning of the input buffer
  * \param[out]  in_pos    The next byte will be read from in[*in_pos].
  * \param       in_size   Size of the input buffer; the first byte that
  *                        won't be read is in[in_size].
  *
  * \return      Slightly different return values are used in multi-call and
  *              single-call modes.
  *
  *              Single-call (vli_pos == NULL):
  *              - LZMA_OK: Integer successfully decoded.
  *              - LZMA_DATA_ERROR: Integer is corrupt. This includes hitting
  *                the end of the input buffer before the whole integer was
  *                decoded; providing no input at all will use LZMA_DATA_ERROR.
  *              - LZMA_PROG_ERROR: Arguments are not sane.
  *
  *              Multi-call (vli_pos != NULL):
  *              - LZMA_OK: So far all OK, but the integer is not
  *                completely decoded yet.
  *              - LZMA_STREAM_END: Integer successfully decoded.
  *              - LZMA_DATA_ERROR: Integer is corrupt.
  *              - LZMA_BUF_ERROR: No input was provided.
  *              - LZMA_PROG_ERROR: Arguments are not sane.
  */
 extern LZMA_API(lzma_ret) lzma_vli_decode(lzma_vli *vli, size_t *vli_pos,
         const uint8_t *in, size_t *in_pos, size_t in_size)
         lzma_nothrow;
 
 
 /**
  * \brief       Get the number of bytes required to encode a VLI
  *
  * \param       vli       Integer whose encoded size is to be determined
  *
  * \return      Number of bytes on success (1-9). If vli isn't valid,
  *              zero is returned.
  */
 extern LZMA_API(uint32_t) lzma_vli_size(lzma_vli vli)
         lzma_nothrow lzma_attr_pure;

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