Tree @831e872 (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_div_d.c @831e872 — 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 | #include "tommath_private.h" #ifdef BN_MP_DIV_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. */ static int s_is_power_of_two(mp_digit b, int *p) { int x; /* fast return if no power of two */ if ((b == 0u) || ((b & (b-1u)) != 0u)) { return 0; } for (x = 0; x < DIGIT_BIT; x++) { if (b == ((mp_digit)1<<(mp_digit)x)) { *p = x; return 1; } } return 0; } /* single digit division (based on routine from MPI) */ int mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d) { mp_int q; mp_word w; mp_digit t; int res, ix; /* cannot divide by zero */ if (b == 0u) { return MP_VAL; } /* quick outs */ if ((b == 1u) || (mp_iszero(a) == MP_YES)) { if (d != NULL) { *d = 0; } if (c != NULL) { return mp_copy(a, c); } return MP_OKAY; } /* power of two ? */ if (s_is_power_of_two(b, &ix) == 1) { if (d != NULL) { *d = a->dp[0] & (((mp_digit)1<<(mp_digit)ix) - 1uL); } if (c != NULL) { return mp_div_2d(a, ix, c, NULL); } return MP_OKAY; } #ifdef BN_MP_DIV_3_C /* three? */ if (b == 3u) { return mp_div_3(a, c, d); } #endif /* no easy answer [c'est la vie]. Just division */ if ((res = mp_init_size(&q, a->used)) != MP_OKAY) { return res; } q.used = a->used; q.sign = a->sign; w = 0; for (ix = a->used - 1; ix >= 0; ix--) { w = (w << (mp_word)DIGIT_BIT) | (mp_word)a->dp[ix]; if (w >= b) { t = (mp_digit)(w / b); w -= (mp_word)t * (mp_word)b; } else { t = 0; } q.dp[ix] = t; } if (d != NULL) { *d = (mp_digit)w; } if (c != NULL) { mp_clamp(&q); mp_exch(&q, c); } mp_clear(&q); return res; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */ |