summaryrefslogtreecommitdiffstats
path: root/libtommath/bn_mp_mul.c
diff options
context:
space:
mode:
Diffstat (limited to 'libtommath/bn_mp_mul.c')
-rw-r--r--libtommath/bn_mp_mul.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/libtommath/bn_mp_mul.c b/libtommath/bn_mp_mul.c
new file mode 100644
index 0000000..fc024be
--- /dev/null
+++ b/libtommath/bn_mp_mul.c
@@ -0,0 +1,62 @@
+#include <tommath.h>
+#ifdef BN_MP_MUL_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
+ */
+
+/* high level multiplication (handles sign) */
+int mp_mul (mp_int * a, mp_int * b, mp_int * c)
+{
+ int res, neg;
+ neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+
+ /* use Toom-Cook? */
+#ifdef BN_MP_TOOM_MUL_C
+ if (MIN (a->used, b->used) >= TOOM_MUL_CUTOFF) {
+ res = mp_toom_mul(a, b, c);
+ } else
+#endif
+#ifdef BN_MP_KARATSUBA_MUL_C
+ /* use Karatsuba? */
+ if (MIN (a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
+ res = mp_karatsuba_mul (a, b, c);
+ } else
+#endif
+ {
+ /* can we use the fast multiplier?
+ *
+ * The fast multiplier can be used if the output will
+ * have less than MP_WARRAY digits and the number of
+ * digits won't affect carry propagation
+ */
+ int digs = a->used + b->used + 1;
+
+#ifdef BN_FAST_S_MP_MUL_DIGS_C
+ if ((digs < MP_WARRAY) &&
+ MIN(a->used, b->used) <=
+ (1 << ((CHAR_BIT * sizeof (mp_word)) - (2 * DIGIT_BIT)))) {
+ res = fast_s_mp_mul_digs (a, b, c, digs);
+ } else
+#endif
+#ifdef BN_S_MP_MUL_DIGS_C
+ res = s_mp_mul (a, b, c); /* uses s_mp_mul_digs */
+#else
+ res = MP_VAL;
+#endif
+
+ }
+ c->sign = (c->used > 0) ? neg : MP_ZPOS;
+ return res;
+}
+#endif