[project @ 1996-01-08 20:28:12 by partain]

[ghc-hetmet.git] / ghc / runtime / gmp / mpq_inv.c

diff --git a/ghc/runtime/gmp/mpq_inv.c b/ghc/runtime/gmp/mpq_inv.c
new file mode 100644 (file)
index 0000000..07fcaa1
--- /dev/null
+++ b/ghc/runtime/gmp/mpq_inv.c
@@ -0,0 +1,74 @@
+/* mpq_inv(dest,src) -- invert a rational number, i.e. set DEST to SRC
+   with the numerator and denominator swapped.
+
+Copyright (C) 1991 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+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 or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with the GNU MP Library; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+void
+#ifdef __STDC__
+mpq_inv (MP_RAT *dest, const MP_RAT *src)
+#else
+mpq_inv (dest, src)
+     MP_RAT *dest;
+     const MP_RAT *src;
+#endif
+{
+  mp_size num_size = src->num.size;
+  mp_size den_size = src->den.size;
+
+  if (num_size == 0)
+    num_size = 1 / num_size;   /* Divide by zero!  */
+
+  if (num_size < 0)
+    {
+      num_size = -num_size;
+      den_size = -den_size;
+    }
+  dest->den.size = num_size;
+  dest->num.size = den_size;
+
+  /* If dest == src we may just swap the numerator and denominator, but
+     we have to ensure the new denominator is positive.  */
+
+  if (dest == src)
+    {
+      mp_size alloc = dest->num.alloc;
+      mp_ptr limb_ptr = dest->num.d;
+
+      dest->num.alloc = dest->den.alloc;
+      dest->num.d = dest->den.d;
+
+      dest->den.alloc = alloc;
+      dest->den.d = limb_ptr;
+    }
+  else
+    {
+      den_size = ABS (den_size);
+      if (dest->num.alloc < den_size)
+       _mpz_realloc (&(dest->num), den_size);
+
+      if (dest->den.alloc < num_size)
+       _mpz_realloc (&(dest->den), num_size);
+
+      MPN_COPY (dest->num.d, src->den.d, den_size);
+      MPN_COPY (dest->den.d, src->num.d, num_size);
+    }
+}