summaryrefslogtreecommitdiff
path: root/libtommath/bn_mp_div_3.c
diff options
context:
space:
mode:
authorSteffen Jaeckel <s_jaeckel@gmx.de>2019-09-16 15:50:38 +0200
committerMatt Johnston <matt@ucc.asn.au>2019-09-16 21:50:38 +0800
commit615ed4e46a52b6bfe0bfc581b8c2fbcc6cc488d1 (patch)
tree12b2ba29ae4c42fc65d64d43968c5d03ab3f4452 /libtommath/bn_mp_div_3.c
parentfa116e983b4931010e1082dd5c8bf38bbc77718c (diff)
downloaddropbear-615ed4e46a52b6bfe0bfc581b8c2fbcc6cc488d1.tar.gz
update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
* make key-generation compliant to FIPS 186.4 * fix includes in tommath_class.h * update fuzzcorpus instead of error-out * fixup fuzzing make-targets * update Makefile.in * apply necessary patches to ltm sources * clean-up not required ltm files * update to vanilla ltm 1.1.0 this already only contains the required files * remove set/get double
Diffstat (limited to 'libtommath/bn_mp_div_3.c')
-rw-r--r--libtommath/bn_mp_div_3.c100
1 files changed, 48 insertions, 52 deletions
diff --git a/libtommath/bn_mp_div_3.c b/libtommath/bn_mp_div_3.c
index e8504ea..db46d44 100644
--- a/libtommath/bn_mp_div_3.c
+++ b/libtommath/bn_mp_div_3.c
@@ -1,4 +1,4 @@
-#include <tommath_private.h>
+#include "tommath_private.h"
#ifdef BN_MP_DIV_3_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
@@ -9,71 +9,67 @@
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
- * The library is free for all purposes without any express
- * guarantee it works.
- *
- * Tom St Denis, tstdenis82@gmail.com, http://libtom.org
+ * SPDX-License-Identifier: Unlicense
*/
/* divide by three (based on routine from MPI and the GMP manual) */
-int
-mp_div_3 (mp_int * a, mp_int *c, mp_digit * d)
+int mp_div_3(const mp_int *a, mp_int *c, mp_digit *d)
{
- mp_int q;
- mp_word w, t;
- mp_digit b;
- int res, ix;
-
- /* b = 2**DIGIT_BIT / 3 */
- b = (((mp_word)1) << ((mp_word)DIGIT_BIT)) / ((mp_word)3);
+ mp_int q;
+ mp_word w, t;
+ mp_digit b;
+ int res, ix;
+
+ /* b = 2**DIGIT_BIT / 3 */
+ b = ((mp_word)1 << (mp_word)DIGIT_BIT) / (mp_word)3;
- if ((res = mp_init_size(&q, a->used)) != MP_OKAY) {
- return res;
- }
-
- q.used = a->used;
- q.sign = a->sign;
- w = 0;
- for (ix = a->used - 1; ix >= 0; ix--) {
- w = (w << ((mp_word)DIGIT_BIT)) | ((mp_word)a->dp[ix]);
+ if ((res = mp_init_size(&q, a->used)) != MP_OKAY) {
+ return res;
+ }
- if (w >= 3) {
- /* multiply w by [1/3] */
- t = (w * ((mp_word)b)) >> ((mp_word)DIGIT_BIT);
+ q.used = a->used;
+ q.sign = a->sign;
+ w = 0;
+ for (ix = a->used - 1; ix >= 0; ix--) {
+ w = (w << (mp_word)DIGIT_BIT) | (mp_word)a->dp[ix];
- /* now subtract 3 * [w/3] from w, to get the remainder */
- w -= t+t+t;
+ if (w >= 3u) {
+ /* multiply w by [1/3] */
+ t = (w * (mp_word)b) >> (mp_word)DIGIT_BIT;
- /* fixup the remainder as required since
- * the optimization is not exact.
- */
- while (w >= 3) {
- t += 1;
- w -= 3;
- }
+ /* now subtract 3 * [w/3] from w, to get the remainder */
+ w -= t+t+t;
+
+ /* fixup the remainder as required since
+ * the optimization is not exact.
+ */
+ while (w >= 3u) {
+ t += 1u;
+ w -= 3u;
+ }
} else {
- t = 0;
+ t = 0;
}
q.dp[ix] = (mp_digit)t;
- }
+ }
+
+ /* [optional] store the remainder */
+ if (d != NULL) {
+ *d = (mp_digit)w;
+ }
- /* [optional] store the remainder */
- if (d != NULL) {
- *d = (mp_digit)w;
- }
+ /* [optional] store the quotient */
+ if (c != NULL) {
+ mp_clamp(&q);
+ mp_exch(&q, c);
+ }
+ mp_clear(&q);
- /* [optional] store the quotient */
- if (c != NULL) {
- mp_clamp(&q);
- mp_exch(&q, c);
- }
- mp_clear(&q);
-
- return res;
+ return res;
}
#endif
-/* ref: $Format:%D$ */
-/* git commit: $Format:%H$ */
-/* commit time: $Format:%ai$ */
+/* ref: HEAD -> master, tag: v1.1.0 */
+/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */