add packaging

[platform/upstream/isl.git] / isl_gmp.c

diff --git a/isl_gmp.c b/isl_gmp.c
index d488fd2..2dbce62 100644 (file)
--- a/isl_gmp.c
+++ b/isl_gmp.c
@@ -1,3 +1,4 @@
+#include <stdio.h>
 /*
  * Copyright 2008-2009 Katholieke Universiteit Leuven
  *
@@ -22,3 +23,36 @@ uint32_t isl_gmp_hash(mpz_t v, uint32_t hash)
                isl_hash_byte(hash, *data);
        return hash;
 }
+
+/* This function tries to produce outputs that do not depend on
+ * the version of GMP that is being used.
+ *
+ * In particular, when computing the extended gcd of -1 and 9,
+ * some versions will produce
+ *
+ *     1 = -1 * -1 + 0 * 9
+ *
+ * while other versions will produce
+ *
+ *     1 = 8 * -1 + 1 * 9
+ *
+ * If configure detects that we are in the former case, then
+ * mpz_gcdext will be called directly.  Otherwise, this function
+ * is called and then we try to mimic the behavior of the other versions.
+ */
+void isl_gmp_gcdext(mpz_t G, mpz_t S, mpz_t T, mpz_t A, mpz_t B)
+{
+       if (mpz_divisible_p(B, A)) {
+               mpz_set_si(S, mpz_sgn(A));
+               mpz_set_si(T, 0);
+               mpz_abs(G, A);
+               return;
+       }
+       if (mpz_divisible_p(A, B)) {
+               mpz_set_si(S, 0);
+               mpz_set_si(T, mpz_sgn(B));
+               mpz_abs(G, B);
+               return;
+       }
+       mpz_gcdext(G, S, T, A, B);
+}