2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
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:
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
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
29 br_i32_decode_mod(uint32_t *x
, const void *src
, size_t len
, const uint32_t *m
)
31 const unsigned char *buf
;
38 * First pass: determine whether the value fits. The 'r' value
39 * will contain the comparison result, as 0x00000000 (value is
40 * equal to the modulus), 0x00000001 (value is greater than the
41 * modulus), or 0xFFFFFFFF (value is lower than the modulus).
43 mlen
= (m
[0] + 7) >> 3;
45 for (u
= (mlen
> len
) ? mlen
: len
; u
> 0; u
--) {
52 mb
= (m
[1 + (v
>> 2)] >> ((v
& 3) << 3)) & 0xFF;
59 r
= MUX(EQ(r
, 0), (uint32_t)CMP(xb
, mb
), r
);
63 * Only r == 0xFFFFFFFF is acceptable. We want to set r to 0xFF if
64 * the value fits, 0x00 otherwise.
68 u
= (mlen
> len
) ? len
: mlen
;
72 xb
= buf
[len
- u
] & r
;
74 x
[1 + (u
>> 2)] |= xb
<< ((u
& 3) << 3);