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Diff for /OpenXM_contrib/gmp/mpn/generic/Attic/gcd_1.c between version 1.1.1.1 and 1.1.1.3

version 1.1.1.1, 2000/01/10 15:35:23 version 1.1.1.3, 2003/08/25 16:06:20
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 /* mpn_gcd_1 --  /* mpn_gcd_1 -- mpn and limb greatest common divisor.
   
 Copyright (C) 1994, 1996 Free Software Foundation, Inc.  Copyright 1994, 1996, 2000, 2001 Free Software Foundation, Inc.
   
 This file is part of the GNU MP Library.  This file is part of the GNU MP Library.
   
 The GNU MP Library is free software; you can redistribute it and/or modify  The GNU MP Library is free software; you can redistribute it and/or modify
 it under the terms of the GNU Library General Public License as published by  it under the terms of the GNU Lesser General Public License as published by
 the Free Software Foundation; either version 2 of the License, or (at your  the Free Software Foundation; either version 2.1 of the License, or (at your
 option) any later version.  option) any later version.
   
 The GNU MP Library is distributed in the hope that it will be useful, but  The GNU MP Library is distributed in the hope that it will be useful, but
 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 License for more details.  License for more details.
   
 You should have received a copy of the GNU Library General Public License  You should have received a copy of the GNU Lesser General Public License
 along with the GNU MP Library; see the file COPYING.LIB.  If not, write to  along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,  the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 MA 02111-1307, USA. */  MA 02111-1307, USA. */
Line 23  MA 02111-1307, USA. */
Line 23  MA 02111-1307, USA. */
 #include "gmp-impl.h"  #include "gmp-impl.h"
 #include "longlong.h"  #include "longlong.h"
   
   
 /* Does not work for U == 0 or V == 0.  It would be tough to make it work for  /* Does not work for U == 0 or V == 0.  It would be tough to make it work for
    V == 0 since gcd(x,0) = x, and U does not generally fit in an mp_limb_t.  */     V == 0 since gcd(x,0) = x, and U does not generally fit in an mp_limb_t.
   
      The threshold for doing u%v when size==1 will vary by CPU according to
      the speed of a division and the code generated for the main loop.  Any
      tuning for this is left to a CPU specific implementation.  */
   
 mp_limb_t  mp_limb_t
 mpn_gcd_1 (up, size, vlimb)  mpn_gcd_1 (mp_srcptr up, mp_size_t size, mp_limb_t vlimb)
      mp_srcptr up;  
      mp_size_t size;  
      mp_limb_t vlimb;  
 {  {
   mp_limb_t ulimb;    mp_limb_t      ulimb;
   unsigned long int u_low_zero_bits, v_low_zero_bits;    unsigned long  zero_bits, u_low_zero_bits;
   
     ASSERT (size >= 1);
     ASSERT (vlimb != 0);
     ASSERT_MPN_NONZERO_P (up, size);
   
     ulimb = up[0];
   
     /* Need vlimb odd for modexact, want it odd to get common zeros. */
     count_trailing_zeros (zero_bits, vlimb);
     vlimb >>= zero_bits;
   
   if (size > 1)    if (size > 1)
     {      {
       ulimb = mpn_mod_1 (up, size, vlimb);        /* Must get common zeros before the mod reduction.  If ulimb==0 then
            vlimb already gives the common zeros.  */
         if (ulimb != 0)
           {
             count_trailing_zeros (u_low_zero_bits, ulimb);
             zero_bits = MIN (zero_bits, u_low_zero_bits);
           }
   
         ulimb = MPN_MOD_OR_MODEXACT_1_ODD (up, size, vlimb);
       if (ulimb == 0)        if (ulimb == 0)
         return vlimb;          goto done;
   
         goto strip_u_maybe;
     }      }
   else  
     ulimb = up[0];  
   
   /*  Need to eliminate low zero bits.  */    /* size==1, so up[0]!=0 */
   count_trailing_zeros (u_low_zero_bits, ulimb);    count_trailing_zeros (u_low_zero_bits, ulimb);
   ulimb >>= u_low_zero_bits;    ulimb >>= u_low_zero_bits;
     zero_bits = MIN (zero_bits, u_low_zero_bits);
   
   count_trailing_zeros (v_low_zero_bits, vlimb);    /* make u bigger */
   vlimb >>= v_low_zero_bits;    if (vlimb > ulimb)
       MP_LIMB_T_SWAP (ulimb, vlimb);
   
     /* if u is much bigger than v, reduce using a division rather than
        chipping away at it bit-by-bit */
     if ((ulimb >> 16) > vlimb)
       {
         ulimb %= vlimb;
         if (ulimb == 0)
           goto done;
         goto strip_u_maybe;
       }
   
   while (ulimb != vlimb)    while (ulimb != vlimb)
     {      {
         ASSERT (ulimb & 1);
         ASSERT (vlimb & 1);
   
       if (ulimb > vlimb)        if (ulimb > vlimb)
         {          {
           ulimb -= vlimb;            ulimb -= vlimb;
           do            do
             ulimb >>= 1;              {
                 ulimb >>= 1;
                 ASSERT (ulimb != 0);
               strip_u_maybe:
                 ;
               }
           while ((ulimb & 1) == 0);            while ((ulimb & 1) == 0);
         }          }
       else /*  vlimb > ulimb.  */        else /*  vlimb > ulimb.  */
         {          {
           vlimb -= ulimb;            vlimb -= ulimb;
           do            do
             vlimb >>= 1;              {
                 vlimb >>= 1;
                 ASSERT (vlimb != 0);
               }
           while ((vlimb & 1) == 0);            while ((vlimb & 1) == 0);
         }          }
     }      }
   
   return  ulimb << MIN (u_low_zero_bits, v_low_zero_bits);   done:
     return vlimb << zero_bits;
 }  }
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  Added in v.1.1.1.3
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