Added generic API for date range validation (with callbacks).
[BearSSL] / int / i31_encode.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_encode(void *dst, size_t len, const uint32_t *x)
30 {
31 unsigned char *buf;
32 size_t k, xlen;
33 uint32_t acc;
34 int acc_len;
35
36 xlen = (x[0] + 31) >> 5;
37 if (xlen == 0) {
38 memset(dst, 0, len);
39 return;
40 }
41 buf = (unsigned char *)dst + len;
42 k = 1;
43 acc = 0;
44 acc_len = 0;
45 while (len != 0) {
46 uint32_t w;
47
48 w = (k <= xlen) ? x[k] : 0;
49 k ++;
50 if (acc_len == 0) {
51 acc = w;
52 acc_len = 31;
53 } else {
54 uint32_t z;
55
56 z = acc | (w << acc_len);
57 acc_len --;
58 acc = w >> (31 - acc_len);
59 if (len >= 4) {
60 buf -= 4;
61 len -= 4;
62 br_enc32be(buf, z);
63 } else {
64 switch (len) {
65 case 3:
66 buf[-3] = (unsigned char)(z >> 16);
67 /* fall through */
68 case 2:
69 buf[-2] = (unsigned char)(z >> 8);
70 /* fall through */
71 case 1:
72 buf[-1] = (unsigned char)z;
73 break;
74 }
75 return;
76 }
77 }
78 }
79 }