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Annotation of OpenXM_contrib/gmp/mpn/generic/mul_basecase.c, Revision 1.1

1.1     ! maekawa     1: /* mpn_mul_basecase -- Internal routine to multiply two natural numbers
        !             2:    of length m and n.
        !             3:
        !             4:    THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE.  IT IS ONLY
        !             5:    SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES.
        !             6:
        !             7:
        !             8: Copyright (C) 1991, 1992, 1993, 1994, 1996, 1997, 2000 Free Software
        !             9: Foundation, Inc.
        !            10:
        !            11: This file is part of the GNU MP Library.
        !            12:
        !            13: The GNU MP Library is free software; you can redistribute it and/or modify
        !            14: it under the terms of the GNU Lesser General Public License as published by
        !            15: the Free Software Foundation; either version 2.1 of the License, or (at your
        !            16: option) any later version.
        !            17:
        !            18: The GNU MP Library is distributed in the hope that it will be useful, but
        !            19: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            20: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
        !            21: License for more details.
        !            22:
        !            23: You should have received a copy of the GNU Lesser General Public License
        !            24: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            25: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            26: MA 02111-1307, USA. */
        !            27:
        !            28: #include "gmp.h"
        !            29: #include "gmp-impl.h"
        !            30:
        !            31: /* Handle simple cases with traditional multiplication.
        !            32:
        !            33:    This is the most critical code of multiplication.  All multiplies rely on
        !            34:    this, both small and huge.  Small ones arrive here immediately, huge ones
        !            35:    arrive here as this is the base case for Karatsuba's recursive algorithm. */
        !            36:
        !            37: void
        !            38: #if __STDC__
        !            39: mpn_mul_basecase (mp_ptr prodp,
        !            40:                     mp_srcptr up, mp_size_t usize,
        !            41:                     mp_srcptr vp, mp_size_t vsize)
        !            42: #else
        !            43: mpn_mul_basecase (prodp, up, usize, vp, vsize)
        !            44:      mp_ptr prodp;
        !            45:      mp_srcptr up;
        !            46:      mp_size_t usize;
        !            47:      mp_srcptr vp;
        !            48:      mp_size_t vsize;
        !            49: #endif
        !            50: {
        !            51:   /* We first multiply by the low order one or two limbs, as the result can
        !            52:      be stored, not added, to PROD.  We also avoid a loop for zeroing this
        !            53:      way.  */
        !            54: #if HAVE_NATIVE_mpn_mul_2
        !            55:   if (vsize >= 2)
        !            56:     {
        !            57:       prodp[usize + 1] = mpn_mul_2 (prodp, up, usize, vp[0], vp[1]);
        !            58:       prodp += 2, vp += 2, vsize -= 2;
        !            59:     }
        !            60:   else
        !            61:     {
        !            62:       prodp[usize] = mpn_mul_1 (prodp, up, usize, vp[0]);
        !            63:       return;
        !            64:     }
        !            65: #else
        !            66:   prodp[usize] = mpn_mul_1 (prodp, up, usize, vp[0]);
        !            67:   prodp += 1, vp += 1, vsize -= 1;
        !            68: #endif
        !            69:
        !            70: #if HAVE_NATIVE_mpn_addmul_2
        !            71:   while (vsize >= 2)
        !            72:     {
        !            73:       prodp[usize + 1] = mpn_addmul_2 (prodp, up, usize, vp[0], vp[1]);
        !            74:       prodp += 2, vp += 2, vsize -= 2;
        !            75:     }
        !            76:   if (vsize != 0)
        !            77:     prodp[usize] = mpn_addmul_1 (prodp, up, usize, vp[0]);
        !            78: #else
        !            79:   /* For each iteration in the loop, multiply U with one limb from V, and
        !            80:      add the result to PROD.  */
        !            81:   while (vsize != 0)
        !            82:     {
        !            83:       prodp[usize] = mpn_addmul_1 (prodp, up, usize, vp[0]);
        !            84:       prodp += 1, vp += 1, vsize -= 1;
        !            85:     }
        !            86: #endif
        !            87: }