70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
|
///////////////////////////////////////////////////////////////////////////////
|
||
|
|
//
|
||
|
|
/// \file vli_encoder.c
|
||
|
|
/// \brief Encodes variable-length integers
|
||
|
|
//
|
||
|
|
// Author: Lasse Collin
|
||
|
|
//
|
||
|
|
// This file has been put into the public domain.
|
||
|
|
// You can do whatever you want with this file.
|
||
|
|
//
|
||
|
|
///////////////////////////////////////////////////////////////////////////////
|
||
|
|
|
||
|
|
#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;
|
||
|
|
|
||
|
|
}
|