1///////////////////////////////////////////////////////////////////////////////
2//
3/// \file       vli_encoder.c
4/// \brief      Encodes variable-length integers
5//
6//  Author:     Lasse Collin
7//
8//  This file has been put into the public domain.
9//  You can do whatever you want with this file.
10//
11///////////////////////////////////////////////////////////////////////////////
12
13#include "common.h"
14
15
16extern LZMA_API(lzma_ret)
17lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
18		uint8_t *restrict out, size_t *restrict out_pos,
19		size_t out_size)
20{
21	// If we haven't been given vli_pos, work in single-call mode.
22	size_t vli_pos_internal = 0;
23	if (vli_pos == NULL) {
24		vli_pos = &vli_pos_internal;
25
26		// In single-call mode, we expect that the caller has
27		// reserved enough output space.
28		if (*out_pos >= out_size)
29			return LZMA_PROG_ERROR;
30	} else {
31		// This never happens when we are called by liblzma, but
32		// may happen if called directly from an application.
33		if (*out_pos >= out_size)
34			return LZMA_BUF_ERROR;
35	}
36
37	// Validate the arguments.
38	if (*vli_pos >= LZMA_VLI_BYTES_MAX || vli > LZMA_VLI_MAX)
39		return LZMA_PROG_ERROR;
40
41	// Shift vli so that the next bits to encode are the lowest. In
42	// single-call mode this never changes vli since *vli_pos is zero.
43	vli >>= *vli_pos * 7;
44
45	// Write the non-last bytes in a loop.
46	while (vli >= 0x80) {
47		// We don't need *vli_pos during this function call anymore,
48		// but update it here so that it is ready if we need to
49		// return before the whole integer has been decoded.
50		++*vli_pos;
51		assert(*vli_pos < LZMA_VLI_BYTES_MAX);
52
53		// Write the next byte.
54		out[*out_pos] = (uint8_t)(vli) | 0x80;
55		vli >>= 7;
56
57		if (++*out_pos == out_size)
58			return vli_pos == &vli_pos_internal
59					? LZMA_PROG_ERROR : LZMA_OK;
60	}
61
62	// Write the last byte.
63	out[*out_pos] = (uint8_t)(vli);
64	++*out_pos;
65	++*vli_pos;
66
67	return vli_pos == &vli_pos_internal ? LZMA_OK : LZMA_STREAM_END;
68
69}
70