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_i31_encode(void * dst,size_t len,const uint32_t * x)29*0957b409SSimon J. Gerraty br_i31_encode(void *dst, size_t len, const uint32_t *x)
30*0957b409SSimon J. Gerraty {
31*0957b409SSimon J. Gerraty unsigned char *buf;
32*0957b409SSimon J. Gerraty size_t k, 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] + 31) >> 5;
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 buf = (unsigned char *)dst + len;
42*0957b409SSimon J. Gerraty k = 1;
43*0957b409SSimon J. Gerraty acc = 0;
44*0957b409SSimon J. Gerraty acc_len = 0;
45*0957b409SSimon J. Gerraty while (len != 0) {
46*0957b409SSimon J. Gerraty uint32_t w;
47*0957b409SSimon J. Gerraty
48*0957b409SSimon J. Gerraty w = (k <= xlen) ? x[k] : 0;
49*0957b409SSimon J. Gerraty k ++;
50*0957b409SSimon J. Gerraty if (acc_len == 0) {
51*0957b409SSimon J. Gerraty acc = w;
52*0957b409SSimon J. Gerraty acc_len = 31;
53*0957b409SSimon J. Gerraty } else {
54*0957b409SSimon J. Gerraty uint32_t z;
55*0957b409SSimon J. Gerraty
56*0957b409SSimon J. Gerraty z = acc | (w << acc_len);
57*0957b409SSimon J. Gerraty acc_len --;
58*0957b409SSimon J. Gerraty acc = w >> (31 - acc_len);
59*0957b409SSimon J. Gerraty if (len >= 4) {
60*0957b409SSimon J. Gerraty buf -= 4;
61*0957b409SSimon J. Gerraty len -= 4;
62*0957b409SSimon J. Gerraty br_enc32be(buf, z);
63*0957b409SSimon J. Gerraty } else {
64*0957b409SSimon J. Gerraty switch (len) {
65*0957b409SSimon J. Gerraty case 3:
66*0957b409SSimon J. Gerraty buf[-3] = (unsigned char)(z >> 16);
67*0957b409SSimon J. Gerraty /* fall through */
68*0957b409SSimon J. Gerraty case 2:
69*0957b409SSimon J. Gerraty buf[-2] = (unsigned char)(z >> 8);
70*0957b409SSimon J. Gerraty /* fall through */
71*0957b409SSimon J. Gerraty case 1:
72*0957b409SSimon J. Gerraty buf[-1] = (unsigned char)z;
73*0957b409SSimon J. Gerraty break;
74*0957b409SSimon J. Gerraty }
75*0957b409SSimon J. Gerraty return;
76*0957b409SSimon J. Gerraty }
77*0957b409SSimon J. Gerraty }
78*0957b409SSimon J. Gerraty }
79*0957b409SSimon J. Gerraty }
80