Donatien Garnier / MiniTLS-GPL

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Dependents:   MiniTLS-HTTPS-Example

math/mul/fp_mul_2d.c@4:cbaf466d717d, 2014-06-10 (annotated)

Committer:
MiniTLS
Date:
Tue Jun 10 14:23:09 2014 +0000
Revision:
4:cbaf466d717d
Parent:
0:35aa5be3b78d 
Fixes for mbed

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MiniTLS 0:35aa5be3b78d 1 /* TomsFastMath, a fast ISO C bignum library.
MiniTLS 0:35aa5be3b78d 2 *
MiniTLS 0:35aa5be3b78d 3 * This project is meant to fill in where LibTomMath
MiniTLS 0:35aa5be3b78d 4 * falls short. That is speed ;-)
MiniTLS 0:35aa5be3b78d 5 *
MiniTLS 0:35aa5be3b78d 6 * This project is public domain and free for all purposes.
MiniTLS 0:35aa5be3b78d 7 *
MiniTLS 0:35aa5be3b78d 8 * Tom St Denis, tomstdenis@gmail.com
MiniTLS 0:35aa5be3b78d 9 */
MiniTLS 0:35aa5be3b78d 10 #include <tfm.h>
MiniTLS 0:35aa5be3b78d 11
MiniTLS 0:35aa5be3b78d 12 /* c = a * 2**d */
MiniTLS 0:35aa5be3b78d 13 void fp_mul_2d(fp_int *a, int b, fp_int *c)
MiniTLS 0:35aa5be3b78d 14 {
MiniTLS 0:35aa5be3b78d 15 fp_digit carry, carrytmp, shift;
MiniTLS 0:35aa5be3b78d 16 int x;
MiniTLS 0:35aa5be3b78d 17
MiniTLS 0:35aa5be3b78d 18 /* copy it */
MiniTLS 0:35aa5be3b78d 19 fp_copy(a, c);
MiniTLS 0:35aa5be3b78d 20
MiniTLS 0:35aa5be3b78d 21 /* handle whole digits */
MiniTLS 0:35aa5be3b78d 22 if (b >= DIGIT_BIT) {
MiniTLS 0:35aa5be3b78d 23 fp_lshd(c, b/DIGIT_BIT);
MiniTLS 0:35aa5be3b78d 24 }
MiniTLS 0:35aa5be3b78d 25 b %= DIGIT_BIT;
MiniTLS 0:35aa5be3b78d 26
MiniTLS 0:35aa5be3b78d 27 /* shift the digits */
MiniTLS 0:35aa5be3b78d 28 if (b != 0) {
MiniTLS 0:35aa5be3b78d 29 carry = 0;
MiniTLS 0:35aa5be3b78d 30 shift = DIGIT_BIT - b;
MiniTLS 0:35aa5be3b78d 31 for (x = 0; x < c->used; x++) {
MiniTLS 0:35aa5be3b78d 32 carrytmp = c->dp[x] >> shift;
MiniTLS 0:35aa5be3b78d 33 c->dp[x] = (c->dp[x] << b) + carry;
MiniTLS 0:35aa5be3b78d 34 carry = carrytmp;
MiniTLS 0:35aa5be3b78d 35 }
MiniTLS 0:35aa5be3b78d 36 /* store last carry if room */
MiniTLS 0:35aa5be3b78d 37 if (carry && x < FP_SIZE) {
MiniTLS 0:35aa5be3b78d 38 c->dp[c->used++] = carry;
MiniTLS 0:35aa5be3b78d 39 }
MiniTLS 0:35aa5be3b78d 40 }
MiniTLS 0:35aa5be3b78d 41 fp_clamp(c);
MiniTLS 0:35aa5be3b78d 42 }
MiniTLS 0:35aa5be3b78d 43
MiniTLS 0:35aa5be3b78d 44
MiniTLS 0:35aa5be3b78d 45 /* $Source: /cvs/libtom/tomsfastmath/src/mul/fp_mul_2d.c,v $ */
MiniTLS 0:35aa5be3b78d 46 /* $Revision: 1.1 $ */
MiniTLS 0:35aa5be3b78d 47 /* $Date: 2006/12/31 21:25:53 $ */