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

[ghc-hetmet.git] / ghc / runtime / gmp / mpz_div_2exp.c

diff --git a/ghc/runtime/gmp/mpz_div_2exp.c b/ghc/runtime/gmp/mpz_div_2exp.c
new file mode 100644 (file)
index 0000000..de67f2f
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+++ b/ghc/runtime/gmp/mpz_div_2exp.c
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+/* mpz_div_2exp -- Divide a bignum by 2**CNT
+
+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__
+mpz_div_2exp (MP_INT *w, const MP_INT *u, unsigned long int cnt)
+#else
+mpz_div_2exp (w, u, cnt)
+     MP_INT *w;
+     const MP_INT *u;
+     unsigned long int cnt;
+#endif
+{
+  mp_size usize = u->size;
+  mp_size wsize;
+  mp_size abs_usize = ABS (usize);
+  mp_size limb_cnt;
+
+  limb_cnt = cnt / BITS_PER_MP_LIMB;
+  wsize = abs_usize - limb_cnt;
+  if (wsize <= 0)
+    wsize = 0;
+  else
+    {
+      if (w->alloc < wsize)
+       _mpz_realloc (w, wsize);
+
+      wsize = mpn_rshift (w->d, u->d + limb_cnt, abs_usize - limb_cnt,
+                          cnt % BITS_PER_MP_LIMB);
+    }
+
+  w->size = (usize >= 0) ? wsize : -wsize;
+}