xref: /freebsd/contrib/bearssl/src/int/i15_encode.c (revision 2aaf9152a852aba9eb2036b95f4948ee77988826)
1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty  * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
3*0957b409SSimon J. Gerraty  *
4*0957b409SSimon J. Gerraty  * Permission is hereby granted, free of charge, to any person obtaining
5*0957b409SSimon J. Gerraty  * a copy of this software and associated documentation files (the
6*0957b409SSimon J. Gerraty  * "Software"), to deal in the Software without restriction, including
7*0957b409SSimon J. Gerraty  * without limitation the rights to use, copy, modify, merge, publish,
8*0957b409SSimon J. Gerraty  * distribute, sublicense, and/or sell copies of the Software, and to
9*0957b409SSimon J. Gerraty  * permit persons to whom the Software is furnished to do so, subject to
10*0957b409SSimon J. Gerraty  * the following conditions:
11*0957b409SSimon J. Gerraty  *
12*0957b409SSimon J. Gerraty  * The above copyright notice and this permission notice shall be
13*0957b409SSimon J. Gerraty  * included in all copies or substantial portions of the Software.
14*0957b409SSimon J. Gerraty  *
15*0957b409SSimon J. Gerraty  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16*0957b409SSimon J. Gerraty  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17*0957b409SSimon J. Gerraty  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18*0957b409SSimon J. Gerraty  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19*0957b409SSimon J. Gerraty  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20*0957b409SSimon J. Gerraty  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21*0957b409SSimon J. Gerraty  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22*0957b409SSimon J. Gerraty  * SOFTWARE.
23*0957b409SSimon J. Gerraty  */
24*0957b409SSimon J. Gerraty 
25*0957b409SSimon J. Gerraty #include "inner.h"
26*0957b409SSimon J. Gerraty 
27*0957b409SSimon J. Gerraty /* see inner.h */
28*0957b409SSimon J. Gerraty void
br_i15_encode(void * dst,size_t len,const uint16_t * x)29*0957b409SSimon J. Gerraty br_i15_encode(void *dst, size_t len, const uint16_t *x)
30*0957b409SSimon J. Gerraty {
31*0957b409SSimon J. Gerraty 	unsigned char *buf;
32*0957b409SSimon J. Gerraty 	size_t u, xlen;
33*0957b409SSimon J. Gerraty 	uint32_t acc;
34*0957b409SSimon J. Gerraty 	int acc_len;
35*0957b409SSimon J. Gerraty 
36*0957b409SSimon J. Gerraty 	xlen = (x[0] + 15) >> 4;
37*0957b409SSimon J. Gerraty 	if (xlen == 0) {
38*0957b409SSimon J. Gerraty 		memset(dst, 0, len);
39*0957b409SSimon J. Gerraty 		return;
40*0957b409SSimon J. Gerraty 	}
41*0957b409SSimon J. Gerraty 	u = 1;
42*0957b409SSimon J. Gerraty 	acc = 0;
43*0957b409SSimon J. Gerraty 	acc_len = 0;
44*0957b409SSimon J. Gerraty 	buf = dst;
45*0957b409SSimon J. Gerraty 	while (len -- > 0) {
46*0957b409SSimon J. Gerraty 		if (acc_len < 8) {
47*0957b409SSimon J. Gerraty 			if (u <= xlen) {
48*0957b409SSimon J. Gerraty 				acc += (uint32_t)x[u ++] << acc_len;
49*0957b409SSimon J. Gerraty 			}
50*0957b409SSimon J. Gerraty 			acc_len += 15;
51*0957b409SSimon J. Gerraty 		}
52*0957b409SSimon J. Gerraty 		buf[len] = (unsigned char)acc;
53*0957b409SSimon J. Gerraty 		acc >>= 8;
54*0957b409SSimon J. Gerraty 		acc_len -= 8;
55*0957b409SSimon J. Gerraty 	}
56*0957b409SSimon J. Gerraty }
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