52 lines
1.6 KiB
C
52 lines
1.6 KiB
C
/*
|
|
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining
|
|
* a copy of this software and associated documentation files (the
|
|
* "Software"), to deal in the Software without restriction, including
|
|
* without limitation the rights to use, copy, modify, merge, publish,
|
|
* distribute, sublicense, and/or sell copies of the Software, and to
|
|
* permit persons to whom the Software is furnished to do so, subject to
|
|
* the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be
|
|
* included in all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
|
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
|
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
|
|
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
|
|
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
|
|
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
|
|
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
* SOFTWARE.
|
|
*/
|
|
|
|
#include "inner.h"
|
|
|
|
/* see inner.h */
|
|
uint32_t
|
|
br_i32_sub(uint32_t *a, const uint32_t *b, uint32_t ctl)
|
|
{
|
|
uint32_t cc;
|
|
size_t u, m;
|
|
|
|
cc = 0;
|
|
m = (a[0] + 63) >> 5;
|
|
for (u = 1; u < m; u ++) {
|
|
uint32_t aw, bw, naw;
|
|
|
|
aw = a[u];
|
|
bw = b[u];
|
|
naw = aw - bw - cc;
|
|
|
|
/*
|
|
* Carry is 1 if naw > aw. Carry is 1 also if naw == aw
|
|
* AND the carry was already 1.
|
|
*/
|
|
cc = (cc & EQ(naw, aw)) | GT(naw, aw);
|
|
a[u] = MUX(ctl, naw, aw);
|
|
}
|
|
return cc;
|
|
}
|