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fix infinite loop in quad_sqrt. courtesy of Martin Schaffner <maschaffner@gmx.ch>

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This commit is contained in:
Bradley Bell 2002-10-28 20:12:48 +00:00
parent 2ebf9b42cc
commit 196af3b1cc
1 changed files with 26 additions and 35 deletions
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61
maths/fixc.c
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@ -1,3 +1,4 @@
/* $Id: fixc.c,v 1.5 2002-10-28 20:12:48 btb Exp $ */
/*
THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
@ -7,37 +8,15 @@ IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
*/
/*
* $Source: /cvs/cvsroot/d2x/maths/fixc.c,v $
* $Revision: 1.4 $
* $Author: btb $
* $Date: 2002-10-28 19:49:15 $
*
*
* C version of fixed point library
*
* $Log: not supported by cvs2svn $
* Revision 1.3 2001/10/31 07:41:54 bradleyb
* Sync with d1x
*
* Revision 1.2 2001/01/31 15:18:04 bradleyb
* Makefile and conf.h fixes
*
* Revision 1.1.1.1 2001/01/19 03:29:58 bradleyb
* Import of d2x-0.0.8
*
* Revision 1.3 1999/10/18 00:31:01 donut
* more alpha fixes from Falk Hueffner
*
* Revision 1.2 1999/08/05 22:53:41 sekmu
*
* D3D patch(es) from ADB
*
* Revision 1.1.1.1 1999/06/14 22:13:35 donut
* Import of d1x 1.37 source.
*
* Old Log:
* Revision 1.7 1995/09/22 14:08:16 allender
* fixed fix_atan2 to work correctly with doubles
*
@ -63,8 +42,8 @@ COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
* --- PC RCS Info ---
* Revision 1.1 1995/03/08 18:55:09 matt
* Initial revision
*
*
*
*
*/
#ifdef HAVE_CONFIG_H
@ -72,7 +51,7 @@ COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
#endif
#ifdef RCS
static char rcsid[] = "$Id: fixc.c,v 1.4 2002-10-28 19:49:15 btb Exp $";
static char rcsid[] = "$Id: fixc.c,v 1.5 2002-10-28 20:12:48 btb Exp $";
#endif
#include <stdlib.h>
@ -321,11 +300,23 @@ int32_t fixdivquadlong(u_int32_t nl,u_int32_t nh,u_int32_t d)
return r;
}
#if 0
// this version caused inf loop with:
// quad_sqrt(0x27eb7121/*low=669741345*/,
// 0x4cd40ad8/*high=1288964824*/);
unsigned int fixdivquadlongu(uint nl, uint nh, uint d)
{
return fixdivquadlong((u_int32_t) nl,(u_int32_t) nh,(u_int32_t) d);
}
#else
#endif
unsigned int fixdivquadlongu(uint nl, uint nh, uint d)
{
u_int64_t n = (u_int64_t)nl | (((u_int64_t)nh) << 32 );
return n / ((u_int64_t)d);
}
#else //of ifdef NO_FIX_INLINE
int32_t fixdivquadlong(u_int32_t nl,u_int32_t nh,u_int32_t d) {
int32_t a;
__asm__("idivl %3"
@ -344,7 +335,7 @@ __asm__("divl %3"
);
return (a);
}
#endif
#endif //def NO_FIX_INLINE
u_int32_t quad_sqrt(u_int32_t low,int32_t high)
{
@ -372,9 +363,9 @@ u_int32_t quad_sqrt(u_int32_t low,int32_t high)
//quad loop usually executed 4 times
r = (fixdivquadlongu(low,high,r)+r)/2;
r = (fixdivquadlongu(low,high,r)+r)/2;
r = (fixdivquadlongu(low,high,r)+r)/2;
r = fixdivquadlongu(low,high,r)/2 + r/2;
r = fixdivquadlongu(low,high,r)/2 + r/2;
r = fixdivquadlongu(low,high,r)/2 + r/2;
do {
@ -384,7 +375,7 @@ u_int32_t quad_sqrt(u_int32_t low,int32_t high)
if (t==r) //got it!
return r;
r = (t+r)/2;
r = t/2 + r/2;
} while (!(r==t || r==old_r));