File Coverage

src/int/i31_fmont.c
Criterion Covered Total %
statement 13 13 100.0
branch 6 6 100.0
condition n/a
subroutine n/a
pod n/a
total 19 19 100.0


line stmt bran cond sub pod time code
1             /*
2             * Copyright (c) 2016 Thomas Pornin
3             *
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:
11             *
12             * The above copyright notice and this permission notice shall be
13             * included in all copies or substantial portions of the Software.
14             *
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
22             * SOFTWARE.
23             */
24              
25             #include "inner.h"
26              
27             /* see inner.h */
28             void
29 4           br_i31_from_monty(uint32_t *x, const uint32_t *m, uint32_t m0i)
30             {
31             size_t len, u, v;
32              
33 4           len = (m[0] + 31) >> 5;
34 40 100         for (u = 0; u < len; u ++) {
35             uint32_t f;
36             uint64_t cc;
37              
38 36           f = MUL31_lo(x[1], m0i);
39 36           cc = 0;
40 360 100         for (v = 0; v < len; v ++) {
41             uint64_t z;
42              
43 324           z = (uint64_t)x[v + 1] + MUL31(f, m[v + 1]) + cc;
44 324           cc = z >> 31;
45 324 100         if (v != 0) {
46 288           x[v] = (uint32_t)z & 0x7FFFFFFF;
47             }
48             }
49 36           x[len] = (uint32_t)cc;
50             }
51              
52             /*
53             * We may have to do an extra subtraction, but only if the
54             * value in x[] is indeed greater than or equal to that of m[],
55             * which is why we must do two calls (first call computes the
56             * carry, second call performs the subtraction only if the carry
57             * is 0).
58             */
59 4           br_i31_sub(x, m, NOT(br_i31_sub(x, m, 0)));
60 4           }