isl_gmp.c

   1 #include <stdio.h>
   2 /*
   3  * Copyright 2008-2009 Katholieke Universiteit Leuven
   4  *
   5  * Use of this software is governed by the MIT license
   6  *
   7  * Written by Sven Verdoolaege, K.U.Leuven, Departement
   8  * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
   9  */
  10
  11 #include <isl_int.h>
  12
  13 uint32_t isl_gmp_hash(mpz_t v, uint32_t hash)
  14 {
  15         int sa = v[0]._mp_size;
  16         int abs_sa = sa < 0 ? -sa : sa;
  17         unsigned char *data = (unsigned char *)v[0]._mp_d;
  18         unsigned char *end = data + abs_sa * sizeof(v[0]._mp_d[0]);
  19
  20         if (sa < 0)
  21                 isl_hash_byte(hash, 0xFF);
  22         for (; data < end; ++data)
  23                 isl_hash_byte(hash, *data);
  24         return hash;
  25 }
  26
  27 /* This function tries to produce outputs that do not depend on
  28  * the version of GMP that is being used.
  29  *
  30  * In particular, when computing the extended gcd of -1 and 9,
  31  * some versions will produce
  32  *
  33  *      1 = -1 * -1 + 0 * 9
  34  *
  35  * while other versions will produce
  36  *
  37  *      1 = 8 * -1 + 1 * 9
  38  *
  39  * If configure detects that we are in the former case, then
  40  * mpz_gcdext will be called directly.  Otherwise, this function
  41  * is called and then we try to mimic the behavior of the other versions.
  42  */
  43 void isl_gmp_gcdext(mpz_t G, mpz_t S, mpz_t T, mpz_t A, mpz_t B)
  44 {
  45         if (mpz_divisible_p(B, A)) {
  46                 mpz_set_si(S, mpz_sgn(A));
  47                 mpz_set_si(T, 0);
  48                 mpz_abs(G, A);
  49                 return;
  50         }
  51         if (mpz_divisible_p(A, B)) {
  52                 mpz_set_si(S, 0);
  53                 mpz_set_si(T, mpz_sgn(B));
  54                 mpz_abs(G, B);
  55                 return;
  56         }
  57         mpz_gcdext(G, S, T, A, B);
  58 }