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///////////////////////////////////////////////////////////////////////////////
//
/// \file vli_encoder.c
/// \brief Encodes variable-length integers
//
// Author: Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////
#include "common.h"
extern LZMA_API(lzma_ret)
lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
uint8_t *restrict out, size_t *restrict out_pos,
size_t out_size)
{
// If we haven't been given vli_pos, work in single-call mode.
size_t vli_pos_internal = 0;
if (vli_pos == NULL) {
vli_pos = &vli_pos_internal;
// In single-call mode, we expect that the caller has
// reserved enough output space.
if (*out_pos >= out_size)
return LZMA_PROG_ERROR;
} else {
// This never happens when we are called by liblzma, but
// may happen if called directly from an application.
if (*out_pos >= out_size)
return LZMA_BUF_ERROR;
}
// Validate the arguments.
if (*vli_pos >= LZMA_VLI_BYTES_MAX || vli > LZMA_VLI_MAX)
return LZMA_PROG_ERROR;
// Shift vli so that the next bits to encode are the lowest. In
// single-call mode this never changes vli since *vli_pos is zero.
vli >>= *vli_pos * 7;
// Write the non-last bytes in a loop.
while (vli >= 0x80) {
// We don't need *vli_pos during this function call anymore,
// but update it here so that it is ready if we need to
// return before the whole integer has been decoded.
++*vli_pos;
assert(*vli_pos < LZMA_VLI_BYTES_MAX);
// Write the next byte.
out[*out_pos] = (uint8_t)(vli) | 0x80;
vli >>= 7;
if (++*out_pos == out_size)
return vli_pos == &vli_pos_internal
? LZMA_PROG_ERROR : LZMA_OK;
}
// Write the last byte.
out[*out_pos] = (uint8_t)(vli);
++*out_pos;
++*vli_pos;
return vli_pos == &vli_pos_internal ? LZMA_OK : LZMA_STREAM_END;
}
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