xref: /freebsd/contrib/bearssl/src/int/i32_decode.c (revision 2aaf9152a852aba9eb2036b95f4948ee77988826)
1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty  * Copyright (c) 2016 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_i32_decode(uint32_t * x,const void * src,size_t len)29*0957b409SSimon J. Gerraty br_i32_decode(uint32_t *x, const void *src, size_t len)
30*0957b409SSimon J. Gerraty {
31*0957b409SSimon J. Gerraty 	const unsigned char *buf;
32*0957b409SSimon J. Gerraty 	size_t u, v;
33*0957b409SSimon J. Gerraty 
34*0957b409SSimon J. Gerraty 	buf = src;
35*0957b409SSimon J. Gerraty 	u = len;
36*0957b409SSimon J. Gerraty 	v = 1;
37*0957b409SSimon J. Gerraty 	for (;;) {
38*0957b409SSimon J. Gerraty 		if (u < 4) {
39*0957b409SSimon J. Gerraty 			uint32_t w;
40*0957b409SSimon J. Gerraty 
41*0957b409SSimon J. Gerraty 			if (u < 2) {
42*0957b409SSimon J. Gerraty 				if (u == 0) {
43*0957b409SSimon J. Gerraty 					break;
44*0957b409SSimon J. Gerraty 				} else {
45*0957b409SSimon J. Gerraty 					w = buf[0];
46*0957b409SSimon J. Gerraty 				}
47*0957b409SSimon J. Gerraty 			} else {
48*0957b409SSimon J. Gerraty 				if (u == 2) {
49*0957b409SSimon J. Gerraty 					w = br_dec16be(buf);
50*0957b409SSimon J. Gerraty 				} else {
51*0957b409SSimon J. Gerraty 					w = ((uint32_t)buf[0] << 16)
52*0957b409SSimon J. Gerraty 						| br_dec16be(buf + 1);
53*0957b409SSimon J. Gerraty 				}
54*0957b409SSimon J. Gerraty 			}
55*0957b409SSimon J. Gerraty 			x[v ++] = w;
56*0957b409SSimon J. Gerraty 			break;
57*0957b409SSimon J. Gerraty 		} else {
58*0957b409SSimon J. Gerraty 			u -= 4;
59*0957b409SSimon J. Gerraty 			x[v ++] = br_dec32be(buf + u);
60*0957b409SSimon J. Gerraty 		}
61*0957b409SSimon J. Gerraty 	}
62*0957b409SSimon J. Gerraty 	x[0] = br_i32_bit_length(x + 1, v - 1);
63*0957b409SSimon J. Gerraty }
64