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

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

diff --git a/ghc/runtime/gmp/mpz_sqrt.c b/ghc/runtime/gmp/mpz_sqrt.c
new file mode 100644 (file)
index 0000000..38408b8
--- /dev/null
+++ b/ghc/runtime/gmp/mpz_sqrt.c
@@ -0,0 +1,87 @@
+/* mpz_sqrt(root, u) --  Set ROOT to floor(sqrt(U)).
+
+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.  */
+
+/* This code is just correct if "unsigned char" has at least 8 bits.  It
+   doesn't help to use CHAR_BIT from limits.h, as the real problem is
+   the static arrays.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+void
+#ifdef __STDC__
+mpz_sqrt (MP_INT *root, const MP_INT *op)
+#else
+mpz_sqrt (root, op)
+     MP_INT *root;
+     const MP_INT *op;
+#endif
+{
+  mp_size op_size, root_size;
+  mp_ptr root_ptr, op_ptr;
+  mp_ptr free_me = NULL;
+  mp_size free_me_size;
+
+  op_size = op->size;
+  if (op_size < 0)
+    op_size = 1 / op_size > 0; /* Divide by zero for negative OP.  */
+
+  /* The size of the root is accurate after this simple calculation.  */
+  root_size = (op_size + 1) / 2;
+
+  root_ptr = root->d;
+  op_ptr = op->d;
+
+  if (root->alloc < root_size)
+    {
+      if (root_ptr == op_ptr)
+       {
+         free_me = root_ptr;
+         free_me_size = root->alloc;
+       }
+      else
+       (*_mp_free_func) (root_ptr, root->alloc * BYTES_PER_MP_LIMB);
+
+      root->alloc = root_size;
+      root_ptr = (mp_ptr) (*_mp_allocate_func) (root_size * BYTES_PER_MP_LIMB);
+      root->d = root_ptr;
+    }
+  else
+    {
+      /* Make OP not overlap with ROOT.  */
+      if (root_ptr == op_ptr)
+       {
+         /* ROOT and OP are identical.  Allocate temporary space for OP.  */
+         op_ptr = (mp_ptr) alloca (op_size * BYTES_PER_MP_LIMB);
+         /* Copy to the temporary space.  Hack: Avoid temporary variable
+          by using ROOT_PTR.  */
+         MPN_COPY (op_ptr, root_ptr, op_size);
+       }
+    }
+
+  mpn_sqrt (root_ptr, NULL, op_ptr, op_size);
+
+  root->size = root_size;
+
+  if (free_me != NULL)
+    (*_mp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
+
+  alloca (0);
+}