Reorganisation of the source tree

[ghc-hetmet.git] / rts / gmp / mpz / pow_ui.c

diff --git a/rts/gmp/mpz/pow_ui.c b/rts/gmp/mpz/pow_ui.c
new file mode 100644 (file)
index 0000000..96ca114
--- /dev/null
+++ b/rts/gmp/mpz/pow_ui.c
@@ -0,0 +1,129 @@
+/* mpz_pow_ui(res, base, exp) -- Set RES to BASE**EXP.
+
+Copyright (C) 1991, 1993, 1994, 1996, 1997 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 Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#ifdef BERKELEY_MP
+#include "mp.h"
+#endif
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+#ifndef BERKELEY_MP
+void
+#if __STDC__
+mpz_pow_ui (mpz_ptr r, mpz_srcptr b, unsigned long int e)
+#else
+mpz_pow_ui (r, b, e)
+     mpz_ptr r;
+     mpz_srcptr b;
+     unsigned long int e;
+#endif
+#else /* BERKELEY_MP */
+void
+#if __STDC__
+rpow (const MINT *b, signed short int e, MINT *r)
+#else
+rpow (b, e, r)
+     const MINT *b;
+     signed short int e;
+     MINT *r;
+#endif
+#endif /* BERKELEY_MP */
+{
+  mp_ptr rp, bp, tp, xp;
+  mp_size_t ralloc, rsize, bsize;
+  int cnt, i;
+  mp_limb_t blimb;
+  TMP_DECL (marker);
+
+  bsize = ABS (b->_mp_size);
+
+  /* Single out cases that give result == 0 or 1.  These tests are here
+     to simplify the general code below, not to optimize.  */
+  if (e == 0)
+    {
+      r->_mp_d[0] = 1;
+      r->_mp_size = 1;
+      return;
+    }
+  if (bsize == 0
+#ifdef BERKELEY_MP
+      || e < 0
+#endif
+      )
+    {
+      r->_mp_size = 0;
+      return;
+    }
+
+  bp = b->_mp_d;
+
+  blimb = bp[bsize - 1];
+  if (bsize == 1 && blimb < 0x100)
+    {
+      /* Estimate space requirements accurately.  Using the code from the
+        `else' path would over-estimate space requirements wildly.   */
+      float lb = __mp_bases[blimb].chars_per_bit_exactly;
+      ralloc = 3 + ((mp_size_t) (e / lb) / BITS_PER_MP_LIMB);
+    }
+  else
+    {
+      /* Over-estimate space requirements somewhat.  */
+      count_leading_zeros (cnt, blimb);
+      ralloc = bsize * e - cnt * e / BITS_PER_MP_LIMB + 2;
+    }
+
+  TMP_MARK (marker);
+
+  /* The two areas are used to alternatingly hold the input and recieve the
+     product for mpn_mul.  (This scheme is used to fulfill the requirements
+     of mpn_mul; that the product space may not be the same as any of the
+     input operands.)  */
+  rp = (mp_ptr) TMP_ALLOC (ralloc * BYTES_PER_MP_LIMB);
+  tp = (mp_ptr) TMP_ALLOC (ralloc * BYTES_PER_MP_LIMB);
+
+  MPN_COPY (rp, bp, bsize);
+  rsize = bsize;
+  count_leading_zeros (cnt, e);
+
+  for (i = BITS_PER_MP_LIMB - cnt - 2; i >= 0; i--)
+    {
+      mpn_mul_n (tp, rp, rp, rsize);
+      rsize = 2 * rsize;
+      rsize -= tp[rsize - 1] == 0;
+      xp = tp; tp = rp; rp = xp;
+
+      if ((e & ((mp_limb_t) 1 << i)) != 0)
+       {
+         rsize = rsize + bsize - (mpn_mul (tp, rp, rsize, bp, bsize) == 0);
+         xp = tp; tp = rp; rp = xp;
+       }
+    }
+
+  /* Now then we know the exact space requirements, reallocate if
+     necessary.  */
+  if (r->_mp_alloc < rsize)
+    _mpz_realloc (r, rsize);
+
+  MPN_COPY (r->_mp_d, rp, rsize);
+  r->_mp_size = (e & 1) == 0 || b->_mp_size >= 0 ? rsize : -rsize;
+  TMP_FREE (marker);
+}