Tree @debian/0.061-1 (Download .tar.gz)
- ..
- bn_error.c
- bn_fast_mp_invmod.c
- bn_fast_mp_montgomery_reduce.c
- bn_fast_s_mp_mul_digs.c
- bn_fast_s_mp_mul_high_digs.c
- bn_fast_s_mp_sqr.c
- bn_mp_2expt.c
- bn_mp_abs.c
- bn_mp_add.c
- bn_mp_add_d.c
- bn_mp_addmod.c
- bn_mp_and.c
- bn_mp_clamp.c
- bn_mp_clear.c
- bn_mp_clear_multi.c
- bn_mp_cmp.c
- bn_mp_cmp_d.c
- bn_mp_cmp_mag.c
- bn_mp_cnt_lsb.c
- bn_mp_copy.c
- bn_mp_count_bits.c
- bn_mp_div.c
- bn_mp_div_2.c
- bn_mp_div_2d.c
- bn_mp_div_3.c
- bn_mp_div_d.c
- bn_mp_dr_is_modulus.c
- bn_mp_dr_reduce.c
- bn_mp_dr_setup.c
- bn_mp_exch.c
- bn_mp_export.c
- bn_mp_expt_d.c
- bn_mp_expt_d_ex.c
- bn_mp_exptmod.c
- bn_mp_exptmod_fast.c
- bn_mp_exteuclid.c
- bn_mp_fread.c
- bn_mp_fwrite.c
- bn_mp_gcd.c
- bn_mp_get_int.c
- bn_mp_get_long.c
- bn_mp_grow.c
- bn_mp_import.c
- bn_mp_init.c
- bn_mp_init_copy.c
- bn_mp_init_multi.c
- bn_mp_init_set.c
- bn_mp_init_set_int.c
- bn_mp_init_size.c
- bn_mp_invmod.c
- bn_mp_invmod_slow.c
- bn_mp_is_square.c
- bn_mp_jacobi.c
- bn_mp_karatsuba_mul.c
- bn_mp_karatsuba_sqr.c
- bn_mp_lcm.c
- bn_mp_lshd.c
- bn_mp_mod.c
- bn_mp_mod_2d.c
- bn_mp_mod_d.c
- bn_mp_montgomery_calc_normalization.c
- bn_mp_montgomery_reduce.c
- bn_mp_montgomery_setup.c
- bn_mp_mul.c
- bn_mp_mul_2.c
- bn_mp_mul_2d.c
- bn_mp_mul_d.c
- bn_mp_mulmod.c
- bn_mp_n_root.c
- bn_mp_n_root_ex.c
- bn_mp_neg.c
- bn_mp_or.c
- bn_mp_prime_fermat.c
- bn_mp_prime_is_divisible.c
- bn_mp_prime_is_prime.c
- bn_mp_prime_miller_rabin.c
- bn_mp_prime_next_prime.c
- bn_mp_prime_rabin_miller_trials.c
- bn_mp_prime_random_ex.c
- bn_mp_radix_size.c
- bn_mp_radix_smap.c
- bn_mp_rand.c
- bn_mp_read_radix.c
- bn_mp_read_signed_bin.c
- bn_mp_read_unsigned_bin.c
- bn_mp_reduce.c
- bn_mp_reduce_2k.c
- bn_mp_reduce_2k_l.c
- bn_mp_reduce_2k_setup.c
- bn_mp_reduce_2k_setup_l.c
- bn_mp_reduce_is_2k.c
- bn_mp_reduce_is_2k_l.c
- bn_mp_reduce_setup.c
- bn_mp_rshd.c
- bn_mp_set.c
- bn_mp_set_int.c
- bn_mp_set_long.c
- bn_mp_shrink.c
- bn_mp_signed_bin_size.c
- bn_mp_sqr.c
- bn_mp_sqrmod.c
- bn_mp_sqrt.c
- bn_mp_sqrtmod_prime.c
- bn_mp_sub.c
- bn_mp_sub_d.c
- bn_mp_submod.c
- bn_mp_to_signed_bin.c
- bn_mp_to_signed_bin_n.c
- bn_mp_to_unsigned_bin.c
- bn_mp_to_unsigned_bin_n.c
- bn_mp_toom_mul.c
- bn_mp_toom_sqr.c
- bn_mp_toradix.c
- bn_mp_toradix_n.c
- bn_mp_unsigned_bin_size.c
- bn_mp_xor.c
- bn_mp_zero.c
- bn_prime_tab.c
- bn_reverse.c
- bn_s_mp_add.c
- bn_s_mp_exptmod.c
- bn_s_mp_mul_digs.c
- bn_s_mp_mul_high_digs.c
- bn_s_mp_sqr.c
- bn_s_mp_sub.c
- bncore.c
- tommath.h
- tommath_class.h
- tommath_private.h
- tommath_superclass.h
bn_mp_gcd.c @debian/0.061-1 — raw · history · blame
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 | #include "tommath_private.h" #ifdef BN_MP_GCD_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. */ /* Greatest Common Divisor using the binary method */ int mp_gcd(const mp_int *a, const mp_int *b, mp_int *c) { mp_int u, v; int k, u_lsb, v_lsb, res; /* either zero than gcd is the largest */ if (mp_iszero(a) == MP_YES) { return mp_abs(b, c); } if (mp_iszero(b) == MP_YES) { return mp_abs(a, c); } /* get copies of a and b we can modify */ if ((res = mp_init_copy(&u, a)) != MP_OKAY) { return res; } if ((res = mp_init_copy(&v, b)) != MP_OKAY) { goto LBL_U; } /* must be positive for the remainder of the algorithm */ u.sign = v.sign = MP_ZPOS; /* B1. Find the common power of two for u and v */ u_lsb = mp_cnt_lsb(&u); v_lsb = mp_cnt_lsb(&v); k = MIN(u_lsb, v_lsb); if (k > 0) { /* divide the power of two out */ if ((res = mp_div_2d(&u, k, &u, NULL)) != MP_OKAY) { goto LBL_V; } if ((res = mp_div_2d(&v, k, &v, NULL)) != MP_OKAY) { goto LBL_V; } } /* divide any remaining factors of two out */ if (u_lsb != k) { if ((res = mp_div_2d(&u, u_lsb - k, &u, NULL)) != MP_OKAY) { goto LBL_V; } } if (v_lsb != k) { if ((res = mp_div_2d(&v, v_lsb - k, &v, NULL)) != MP_OKAY) { goto LBL_V; } } while (mp_iszero(&v) == MP_NO) { /* make sure v is the largest */ if (mp_cmp_mag(&u, &v) == MP_GT) { /* swap u and v to make sure v is >= u */ mp_exch(&u, &v); } /* subtract smallest from largest */ if ((res = s_mp_sub(&v, &u, &v)) != MP_OKAY) { goto LBL_V; } /* Divide out all factors of two */ if ((res = mp_div_2d(&v, mp_cnt_lsb(&v), &v, NULL)) != MP_OKAY) { goto LBL_V; } } /* multiply by 2**k which we divided out at the beginning */ if ((res = mp_mul_2d(&u, k, c)) != MP_OKAY) { goto LBL_V; } c->sign = MP_ZPOS; res = MP_OKAY; LBL_V: mp_clear(&u); LBL_U: mp_clear(&v); return res; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */ |