1/*
2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25#include "inner.h"
26
27/* see inner.h */
28void
29br_i32_encode(void *dst, size_t len, const uint32_t *x)
30{
31	unsigned char *buf;
32	size_t k;
33
34	buf = dst;
35
36	/*
37	 * Compute the announced size of x in bytes; extra bytes are
38	 * filled with zeros.
39	 */
40	k = (x[0] + 7) >> 3;
41	while (len > k) {
42		*buf ++ = 0;
43		len --;
44	}
45
46	/*
47	 * Now we use k as index within x[]. That index starts at 1;
48	 * we initialize it to the topmost complete word, and process
49	 * any remaining incomplete word.
50	 */
51	k = (len + 3) >> 2;
52	switch (len & 3) {
53	case 3:
54		*buf ++ = x[k] >> 16;
55		/* fall through */
56	case 2:
57		*buf ++ = x[k] >> 8;
58		/* fall through */
59	case 1:
60		*buf ++ = x[k];
61		k --;
62	}
63
64	/*
65	 * Encode all complete words.
66	 */
67	while (k > 0) {
68		br_enc32be(buf, x[k]);
69		k --;
70		buf += 4;
71	}
72}
73