diff options
Diffstat (limited to 'libtommath/bn_mp_reduce.c')
-rw-r--r-- | libtommath/bn_mp_reduce.c | 64 |
1 files changed, 25 insertions, 39 deletions
diff --git a/libtommath/bn_mp_reduce.c b/libtommath/bn_mp_reduce.c index 9cb9d2a..3c669d4 100644 --- a/libtommath/bn_mp_reduce.c +++ b/libtommath/bn_mp_reduce.c @@ -1,86 +1,76 @@ #include "tommath_private.h" #ifdef BN_MP_REDUCE_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. - * - * SPDX-License-Identifier: Unlicense - */ +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ /* reduces x mod m, assumes 0 < x < m**2, mu is * precomputed via mp_reduce_setup. * From HAC pp.604 Algorithm 14.42 */ -int mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu) +mp_err mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu) { mp_int q; - int res, um = m->used; + mp_err err; + int um = m->used; /* q = x */ - if ((res = mp_init_copy(&q, x)) != MP_OKAY) { - return res; + if ((err = mp_init_copy(&q, x)) != MP_OKAY) { + return err; } /* q1 = x / b**(k-1) */ mp_rshd(&q, um - 1); /* according to HAC this optimization is ok */ - if ((mp_digit)um > ((mp_digit)1 << (DIGIT_BIT - 1))) { - if ((res = mp_mul(&q, mu, &q)) != MP_OKAY) { + if ((mp_digit)um > ((mp_digit)1 << (MP_DIGIT_BIT - 1))) { + if ((err = mp_mul(&q, mu, &q)) != MP_OKAY) { goto CLEANUP; } - } else { -#ifdef BN_S_MP_MUL_HIGH_DIGS_C - if ((res = s_mp_mul_high_digs(&q, mu, &q, um)) != MP_OKAY) { + } else if (MP_HAS(S_MP_MUL_HIGH_DIGS)) { + if ((err = s_mp_mul_high_digs(&q, mu, &q, um)) != MP_OKAY) { goto CLEANUP; } -#elif defined(BN_FAST_S_MP_MUL_HIGH_DIGS_C) - if ((res = fast_s_mp_mul_high_digs(&q, mu, &q, um)) != MP_OKAY) { + } else if (MP_HAS(S_MP_MUL_HIGH_DIGS_FAST)) { + if ((err = s_mp_mul_high_digs_fast(&q, mu, &q, um)) != MP_OKAY) { goto CLEANUP; } -#else - { - res = MP_VAL; - goto CLEANUP; - } -#endif + } else { + err = MP_VAL; + goto CLEANUP; } /* q3 = q2 / b**(k+1) */ mp_rshd(&q, um + 1); /* x = x mod b**(k+1), quick (no division) */ - if ((res = mp_mod_2d(x, DIGIT_BIT * (um + 1), x)) != MP_OKAY) { + if ((err = mp_mod_2d(x, MP_DIGIT_BIT * (um + 1), x)) != MP_OKAY) { goto CLEANUP; } /* q = q * m mod b**(k+1), quick (no division) */ - if ((res = s_mp_mul_digs(&q, m, &q, um + 1)) != MP_OKAY) { + if ((err = s_mp_mul_digs(&q, m, &q, um + 1)) != MP_OKAY) { goto CLEANUP; } /* x = x - q */ - if ((res = mp_sub(x, &q, x)) != MP_OKAY) { + if ((err = mp_sub(x, &q, x)) != MP_OKAY) { goto CLEANUP; } /* If x < 0, add b**(k+1) to it */ if (mp_cmp_d(x, 0uL) == MP_LT) { mp_set(&q, 1uL); - if ((res = mp_lshd(&q, um + 1)) != MP_OKAY) + if ((err = mp_lshd(&q, um + 1)) != MP_OKAY) { goto CLEANUP; - if ((res = mp_add(x, &q, x)) != MP_OKAY) + } + if ((err = mp_add(x, &q, x)) != MP_OKAY) { goto CLEANUP; + } } /* Back off if it's too big */ while (mp_cmp(x, m) != MP_LT) { - if ((res = s_mp_sub(x, m, x)) != MP_OKAY) { + if ((err = s_mp_sub(x, m, x)) != MP_OKAY) { goto CLEANUP; } } @@ -88,10 +78,6 @@ int mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu) CLEANUP: mp_clear(&q); - return res; + return err; } #endif - -/* ref: HEAD -> master, tag: v1.1.0 */ -/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ -/* commit time: 2019-01-28 20:32:32 +0100 */ |