# HG changeset patch
# User james
# Date 1081284740 0
# Node ID 4f5e0297b73fc6094713e1fa9958f52c918e9f38
# Parent  55bab11c30e8bdd7f058894fd2deb6e6c1a35c92
[xemacs-hg @ 2004-04-06 20:52:08 by james]
Fix bignum_to_double so it actually gives the right answer.

diff -r 55bab11c30e8 -r 4f5e0297b73f src/ChangeLog
--- a/src/ChangeLog	Tue Apr 06 20:50:39 2004 +0000
+++ b/src/ChangeLog	Tue Apr 06 20:52:20 2004 +0000
@@ -1,3 +1,7 @@
+2004-04-06  Jerry James  <james@xemacs.org>
+
+	* number-mp.c (bignum_to_double): Original algorithm was wrong.
+
 2004-04-06  Stephen J. Turnbull  <stephen@xemacs.org>
 
 	* lisp.h (Other numeric types): Band-aid: #define make_integer.
diff -r 55bab11c30e8 -r 4f5e0297b73f src/number-mp.c
--- a/src/number-mp.c	Tue Apr 06 20:50:39 2004 +0000
+++ b/src/number-mp.c	Tue Apr 06 20:52:20 2004 +0000
@@ -159,17 +159,18 @@
 bignum_to_double (bignum b)
 {
   short rem, sign;
-  double retval = 0.0;
+  double retval = 0.0, factor = 1.0;
   REGISTER unsigned int i;
   MINT *quo;
 
   sign = MP_MCMP (b, bignum_zero) < 0 ? -1 : 1;
   quo = MP_ITOM (sign);
   MP_MULT (b, quo, quo);
-  for (i = 0U; MP_MCMP(quo, bignum_zero) > 0; i++)
+  for (i = 0U; MP_MCMP (quo, bignum_zero) > 0; i++)
     {
       MP_SDIV (quo, 256, quo, &rem);
-      retval += rem * i * 256;
+      retval += rem * factor;
+      factor *= 256.0;
     }
   MP_MFREE (quo);
   return retval * sign;