diff options
Diffstat (limited to 'libtommath/bn_mp_mul.c')
-rw-r--r-- | libtommath/bn_mp_mul.c | 62 |
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 |