Added generic API for date range validation (with callbacks).
[BearSSL] / int / i31_decode.c
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 */
28 void
29 br_i31_decode(uint32_t *x, const void *src, size_t len)
30 {
31 const unsigned char *buf;
32 size_t u, v;
33 uint32_t acc;
34 int acc_len;
35
36 buf = src;
37 u = len;
38 v = 1;
39 acc = 0;
40 acc_len = 0;
41 while (u -- > 0) {
42 uint32_t b;
43
44 b = buf[u];
45 acc |= (b << acc_len);
46 acc_len += 8;
47 if (acc_len >= 31) {
48 x[v ++] = acc & (uint32_t)0x7FFFFFFF;
49 acc_len -= 31;
50 acc = b >> (8 - acc_len);
51 }
52 }
53 if (acc_len != 0) {
54 x[v ++] = acc;
55 }
56 x[0] = br_i31_bit_length(x + 1, v - 1);
57 }