diff options
Diffstat (limited to 'libtommath/bn_mp_gcd.c')
| -rw-r--r-- | libtommath/bn_mp_gcd.c | 138 |
1 files changed, 69 insertions, 69 deletions
diff --git a/libtommath/bn_mp_gcd.c b/libtommath/bn_mp_gcd.c index b39ba90..e7a155b 100644 --- a/libtommath/bn_mp_gcd.c +++ b/libtommath/bn_mp_gcd.c @@ -16,87 +16,87 @@ */ /* Greatest Common Divisor using the binary method */ -int mp_gcd (mp_int * a, mp_int * b, mp_int * c) +int mp_gcd(mp_int * a, mp_int * b, mp_int * c) { - mp_int u, v; - int k, u_lsb, v_lsb, res; + 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); - } + /* 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; - } + /* 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; - } + 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; + /* 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); + /* 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 (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; - } - } + 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; - } - } + /* 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; - } - } + if (v_lsb != k) { + if ((res = mp_div_2d(&v, v_lsb - k, &v, NULL)) != MP_OKAY) { + goto LBL_V; + } + } - while (mp_iszero(&v) == 0) { - /* 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; - } - } + while (mp_iszero(&v) == 0) { + /* 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); + } - /* 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; + /* 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 |