===================================================================
RCS file: /home/cvs/OpenXM_contrib/gmp/mpz/Attic/ui_pow_ui.c,v
retrieving revision 1.1.1.1
retrieving revision 1.1.1.2
diff -u -p -r1.1.1.1 -r1.1.1.2
--- OpenXM_contrib/gmp/mpz/Attic/ui_pow_ui.c	2000/01/10 15:35:27	1.1.1.1
+++ OpenXM_contrib/gmp/mpz/Attic/ui_pow_ui.c	2000/09/09 14:13:00	1.1.1.2
@@ -1,20 +1,21 @@
 /* mpz_ui_pow_ui(res, base, exp) -- Set RES to BASE**EXP.
 
-Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
+Copyright (C) 1991, 1993, 1994, 1996, 1997, 2000 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 Library General Public License as published by
-the Free Software Foundation; either version 2 of the License, or (at your
+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 Library General Public
+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 Library General Public License
+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. */
@@ -23,6 +24,9 @@ MA 02111-1307, USA. */
 #include "gmp-impl.h"
 #include "longlong.h"
 
+
+static void mpz_pow2 _PROTO ((mpz_ptr r, mp_limb_t blimb, unsigned long int e, mp_limb_t rl));
+
 void
 #if __STDC__
 mpz_ui_pow_ui (mpz_ptr r, unsigned long int b, unsigned long int e)
@@ -33,79 +37,103 @@ mpz_ui_pow_ui (r, b, e)
      unsigned long int e;
 #endif
 {
-  mp_ptr rp, tp, xp;
-  mp_size_t rsize;
-  int cnt, i;
   mp_limb_t blimb = b;
-  TMP_DECL (marker);
+  mp_limb_t rl;
 
-  /* 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)
     {
+      /* For x^0 we return 1, even if x is 0.  */
       r->_mp_d[0] = 1;
       r->_mp_size = 1;
       return;
     }
-  if (blimb == 0)
+
+  /* Compute b^e as (b^n)^(e div n) * b^(e mod n), where n is chosen such that
+     the latter factor is the largest number small enough to fit in a limb.  */
+
+  rl = 1;
+  while (e != 0 && blimb < ((mp_limb_t) 1 << BITS_PER_MP_LIMB/2))
     {
-      r->_mp_size = 0;
-      return;
+      if ((e & 1) != 0)
+	rl = rl * blimb;
+      blimb = blimb * blimb;
+      e = e >> 1;
     }
 
-  if (blimb < 0x100)
+  /* rl is now b^(e mod n).  (I.e., the latter factor above.)  */
+
+  if (e == 0)
     {
-      /* 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;
-      rsize = 2 + ((mp_size_t) (e / lb) / BITS_PER_MP_LIMB);
+      r->_mp_d[0] = rl;
+      r->_mp_size = rl != 0;
+      return;
     }
-  else
-    {
-      /* Over-estimate space requirements somewhat.  */
-      count_leading_zeros (cnt, blimb);
-      rsize = e - cnt * e / BITS_PER_MP_LIMB + 1;
-    }
 
+  mpz_pow2 (r, blimb, e, rl);
+}
+
+/* Multi-precision part of expontialization code.  */
+static void
+#if __STDC__
+mpz_pow2 (mpz_ptr r, mp_limb_t blimb, unsigned long int e, mp_limb_t rl)
+#else
+mpz_pow2 (r, blimb, e, rl)
+     mpz_ptr r;
+     mp_limb_t blimb;
+     unsigned long int e;
+     mp_limb_t rl;
+#endif
+{
+  mp_ptr rp, tp;
+  mp_size_t ralloc, rsize;
+  int cnt, i;
+  TMP_DECL (marker);
+
   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 (rsize * BYTES_PER_MP_LIMB);
-  tp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB);
+  /* Over-estimate temporary space requirements somewhat.  */
+  count_leading_zeros (cnt, blimb);
+  ralloc = e - cnt * e / BITS_PER_MP_LIMB + 1;
 
+  /* The two areas are used to alternatingly hold the input and receive the
+     product for mpn_mul.  (Needed since mpn_mul_n requires that the product
+     is distinct from either input operand.)  */
+  rp = (mp_ptr) TMP_ALLOC (ralloc * BYTES_PER_MP_LIMB);
+  tp = (mp_ptr) TMP_ALLOC (ralloc * BYTES_PER_MP_LIMB);
+
   rp[0] = blimb;
   rsize = 1;
-  count_leading_zeros (cnt, e);
 
+  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;
+      MP_PTR_SWAP (rp, tp);
 
       if ((e & ((mp_limb_t) 1 << i)) != 0)
 	{
 	  mp_limb_t cy;
-	  cy = mpn_mul_1 (tp, rp, rsize, blimb);
-	  if (cy != 0)
-	    {
-	      tp[rsize] = cy;
-	      rsize++;
-	    }
-	  xp = tp; tp = rp; rp = xp;
+	  cy = mpn_mul_1 (rp, rp, rsize, blimb);
+	  rp[rsize] = cy;
+	  rsize += cy != 0;
 	}
     }
 
-  /* Now then we know the exact space requirements, reallocate if
-     necessary.  */
-  if (r->_mp_alloc < rsize)
-    _mpz_realloc (r, rsize);
+  /* We will need rsize or rsize+1 limbs for the result.  */
+  if (r->_mp_alloc <= rsize)
+    _mpz_realloc (r, rsize + 1);
 
-  MPN_COPY (r->_mp_d, rp, rsize);
+  /* Multiply the two factors (in rp,rsize and rl) and put the final result
+     in place.  */
+  {
+    mp_limb_t cy;
+    cy = mpn_mul_1 (r->_mp_d, rp, rsize, rl);
+    (r->_mp_d)[rsize] = cy;
+    rsize += cy != 0;
+  }
+
   r->_mp_size = rsize;
   TMP_FREE (marker);
 }