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authorWilliam Joye <wjoye@cfa.harvard.edu>2016-12-21 22:46:09 (GMT)
committerWilliam Joye <wjoye@cfa.harvard.edu>2016-12-21 22:46:09 (GMT)
commit768f87f613cc9789fcf8073018fa02178c8c91df (patch)
treeec633f5608ef498bee52a5f42c12c49493ec8bf8 /tcl8.6/libtommath/bn_mp_mul_d.c
parent07e464099b99459d0a37757771791598ef3395d9 (diff)
parent05fa4c89f20e9769db0e6c0b429cef2590771ace (diff)
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Merge commit '05fa4c89f20e9769db0e6c0b429cef2590771ace' as 'tcl8.6'
Diffstat (limited to 'tcl8.6/libtommath/bn_mp_mul_d.c')
-rw-r--r--tcl8.6/libtommath/bn_mp_mul_d.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/tcl8.6/libtommath/bn_mp_mul_d.c b/tcl8.6/libtommath/bn_mp_mul_d.c
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+++ b/tcl8.6/libtommath/bn_mp_mul_d.c
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+#include <tommath.h>
+#ifdef BN_MP_MUL_D_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * 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, tomstdenis@gmail.com, http://math.libtomcrypt.com
+ */
+
+/* multiply by a digit */
+int
+mp_mul_d (mp_int * a, mp_digit b, mp_int * c)
+{
+ mp_digit u, *tmpa, *tmpc;
+ mp_word r;
+ int ix, res, olduse;
+
+ /* make sure c is big enough to hold a*b */
+ if (c->alloc < a->used + 1) {
+ if ((res = mp_grow (c, a->used + 1)) != MP_OKAY) {
+ return res;
+ }
+ }
+
+ /* get the original destinations used count */
+ olduse = c->used;
+
+ /* set the sign */
+ c->sign = a->sign;
+
+ /* alias for a->dp [source] */
+ tmpa = a->dp;
+
+ /* alias for c->dp [dest] */
+ tmpc = c->dp;
+
+ /* zero carry */
+ u = 0;
+
+ /* compute columns */
+ for (ix = 0; ix < a->used; ix++) {
+ /* compute product and carry sum for this term */
+ r = ((mp_word) u) + ((mp_word)*tmpa++) * ((mp_word)b);
+
+ /* mask off higher bits to get a single digit */
+ *tmpc++ = (mp_digit) (r & ((mp_word) MP_MASK));
+
+ /* send carry into next iteration */
+ u = (mp_digit) (r >> ((mp_word) DIGIT_BIT));
+ }
+
+ /* store final carry [if any] and increment ix offset */
+ *tmpc++ = u;
+ ++ix;
+
+ /* now zero digits above the top */
+ while (ix++ < olduse) {
+ *tmpc++ = 0;
+ }
+
+ /* set used count */
+ c->used = a->used + 1;
+ mp_clamp(c);
+
+ return MP_OKAY;
+}
+#endif