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Diff for /OpenXM_contrib/gmp/mpz/Attic/kronsz.c between version 1.1.1.1 and 1.1.1.2

version 1.1.1.1, 2000/09/09 14:12:54 version 1.1.1.2, 2003/08/25 16:06:33
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 /* mpz_si_kronecker -- Kronecker/Jacobi symbol. */  /* mpz_si_kronecker -- long+mpz Kronecker/Jacobi symbol.
   
 /*  Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
 Copyright (C) 1999, 2000 Free Software Foundation, Inc.  
   
 This file is part of the GNU MP Library.  This file is part of the GNU MP Library.
   
Line 18  License for more details.
Line 17  License for more details.
 You should have received a copy of the GNU Lesser 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. */
 */  
   
 #include "gmp.h"  #include "gmp.h"
 #include "gmp-impl.h"  #include "gmp-impl.h"
 #include "longlong.h"  #include "longlong.h"
   
   
   /* This implementation depends on BITS_PER_MP_LIMB being even, so that
      (a/2)^BITS_PER_MP_LIMB = 1 and so there's no need to pay attention to how
      many low zero limbs are stripped.  */
   #if BITS_PER_MP_LIMB % 2 != 0
   Error, error, unsupported BITS_PER_MP_LIMB
   #endif
   
   
 int  int
 #if __STDC__  
 mpz_si_kronecker (long a, mpz_srcptr b)  mpz_si_kronecker (long a, mpz_srcptr b)
 #else  
 mpz_si_kronecker (a, b)  
      long       a;  
      mpz_srcptr b;  
 #endif  
 {  {
   int        b_abs_size;    mp_srcptr  b_ptr = PTR(b);
   mp_srcptr  b_ptr;    mp_limb_t  b_low = b_ptr[0];
   mp_limb_t  b_low;    mp_size_t  b_size = SIZ (b);
   int        twos;    mp_size_t  b_abs_size = ABS (b_size);
     mp_limb_t  a_limb, b_rem;
     unsigned   twos;
   int        result_bit1;    int        result_bit1;
   
   b_abs_size = ABSIZ (b);  #if GMP_NUMB_BITS < BITS_PER_ULONG
     if (a > GMP_NUMB_MAX || a < -GMP_NUMB_MAX)
       {
         mp_limb_t  alimbs[2];
         mpz_t      az;
         ALLOC(az) = numberof (alimbs);
         PTR(az) = alimbs;
         mpz_set_si (az, a);
         return mpz_kronecker (az, b);
       }
   #endif
   
   if (b_abs_size == 0)    if (b_abs_size == 0)
     return JACOBI_S0 (a);  /* (a/0) */      return JACOBI_S0 (a);  /* (a/0) */
   
   b_ptr = PTR(b);    /* account for the effect of the sign of b, then ignore it */
   b_low = b_ptr[0];    result_bit1 = JACOBI_BSGN_SS_BIT1 (a, b_size);
   
   /* (0/b) = 1 if b=+/-1, 0 otherwise */    if ((b_low & 1) != 0)
   if (a == 0)      {
     return (b_abs_size == 1) & (b_low == 1);        /* b odd */
   
   /* account for the effect of the sign of b, so can then ignore it */        result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a, b_low);
   result_bit1 = JACOBI_BSGN_SZ_BIT1 (a, b);        a_limb = (unsigned long) ABS(a);
   
   if ((b_low & 1) == 0)        if ((a_limb & 1) == 0)
     {          {
       /* b even */            /* (0/b)=1 for b=+/-1, 0 otherwise */
             if (a_limb == 0)
               return (b_abs_size == 1 && b_low == 1);
   
             /* a even, b odd */
             count_trailing_zeros (twos, a_limb);
             a_limb >>= twos;
             /* (a*2^n/b) = (a/b) * twos(n,a) */
             result_bit1 ^= JACOBI_TWOS_U_BIT1 (twos, b_low);
           }
       }
     else
       {
         /* (even/even)=0, and (0/b)=0 for b!=+/-1 */
       if ((a & 1) == 0)        if ((a & 1) == 0)
         return 0;  /* (a/b)=0 if both a,b even */          return 0;
   
       /* Require MP_BITS_PER_LIMB even, so that (a/2)^MP_BITS_PER_LIMB = 1,        /* a odd, b even */
          and so that therefore there's no need to account for how many zero  
          limbs are stripped.  */  
       ASSERT ((BITS_PER_MP_LIMB & 1) == 0);  
   
       MPN_STRIP_LOW_ZEROS_NOT_ZERO (b_ptr, b_abs_size);        /* establish shifted b_low with valid bit1 for use with ASGN and RECIP */
       b_low = b_ptr[0];        MPN_STRIP_LOW_ZEROS_NOT_ZERO (b_ptr, b_abs_size, b_low);
   
       if ((b_low & 1) == 0)        if ((b_low & 1) == 0)
         {          {
           /* odd a, even b */            if (b_low == GMP_NUMB_HIGHBIT)
               {
                 if (b_abs_size == 1)
                   {
                     /* (a/0x80000000) = (a/2)^(BPML-1) */
                     result_bit1 ^= JACOBI_TWOS_U_BIT1 (GMP_NUMB_BITS - 1, a);
                     return JACOBI_BIT1_TO_PN (result_bit1);
                   }
   
           mp_limb_t  b_shl_bit1;                /* b_abs_size > 1 */
                 b_low = b_ptr[1] << 1;
           count_trailing_zeros (twos, b_low);              }
   
           /* b_shl_bit1 is b>>twos, but with only bit 1 guaranteed */  
           if (twos == BITS_PER_MP_LIMB-1)  
             b_shl_bit1 = (b_abs_size == 1) ? 0 : (b_ptr[1] << 1);  
           else            else
             b_shl_bit1 = (b_low >> twos);              {
                 count_trailing_zeros (twos, b_low);
           result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a, b_shl_bit1);                b_low >>= twos;
           a = ABS(a);              }
   
           if (a == 1)  
             return JACOBI_BIT1_TO_PN (result_bit1);  /* (1/b)=1 */  
   
           /* twos (a/2), reciprocity to (b/a), and (b/a) = (b mod a / b) */  
           return mpn_jacobi_base (mpn_mod_1_rshift (b_ptr, b_abs_size,  
                                                     twos, a),  
                                   a,  
                                   result_bit1  
                                   ^ JACOBI_TWOS_U_BIT1 (twos, a)  
                                   ^ JACOBI_RECIP_UU_BIT1 (a, b_shl_bit1));  
         }          }
     }  
   
   /* b odd */        result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a, b_low);
         a_limb = (unsigned long) ABS(a);
   result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a, b_low);  
   a = ABS(a);  
   
   /* (a/1) = 1 for any a */  
   if (b_abs_size == 1 && b_low == 1)  
     return JACOBI_BIT1_TO_PN (result_bit1);  
   
   /* Note a is cast to unsigned because 0x80..00 doesn't fit in a signed. */  
   if ((a & 1) == 0)  
     {  
       count_trailing_zeros (twos, a);  
       a = ((unsigned long) a) >> twos;  
       result_bit1 ^= JACOBI_TWOS_U_BIT1 (twos, b_low);  
     }      }
   
   if (a == 1)    if (a_limb == 1)
     return JACOBI_BIT1_TO_PN (result_bit1);  /* (1/b)=1 */      return JACOBI_BIT1_TO_PN (result_bit1);  /* (1/b)=1 */
   
   /* reciprocity to (b/a), and (b/a) == (b mod a / a) */    /* (a/b*2^n) = (b*2^n mod a / a) * recip(a,b) */
   return mpn_jacobi_base (mpn_mod_1 (b_ptr, b_abs_size, a), a,    JACOBI_MOD_OR_MODEXACT_1_ODD (result_bit1, b_rem, b_ptr, b_abs_size, a_limb);
                           result_bit1 ^ JACOBI_RECIP_UU_BIT1 (a, b_low));    result_bit1 ^= JACOBI_RECIP_UU_BIT1 (a_limb, b_low);
     return mpn_jacobi_base (b_rem, a_limb, result_bit1);
 }  }
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