[ballen@uwm.edu] libc/2269: triginometric argument reduction error in libm

[Andreas Jaeger]

Bruce Allen <ballen@gravity.phys.uwm.edu> writes:

> On Sun, 20 May 2001, Geoff Keating wrote:
> 
> > Someone needs to fix libc/sysdeps/i386/fpu/s_sin.S so that it does
> > proper range reduction, I think.  It works fine on non-x86 chips.
> > 
> > Intel's manual (I was looking at the 'Pentium Processor Family
> > Developer's Manual, volume 3') has some spectacularly bad advice on
> > how to do range reduction.  I would suggest ignoring it.
> 
> Geoff, 
> 
> Could you please give a URL for this manual?  I'm familiar enough with the
> problems of range reduction to be interested in seeing how they got it
> wrong.

Just for reference, I'm appending the ia32 double sin implementation.

Andreas

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/*
 * Written by J.T. Conklin <jtc@netbsd.org>.
 * Public domain.
 */

#include <machine/asm.h>

RCSID("$NetBSD: s_sin.S,v 1.5 1995/05/09 00:25:54 jtc Exp $")

ENTRY(__sin)
	fldl	4(%esp)
	fsin
	fnstsw	%ax
	testl	$0x400,%eax
	jnz	1f
	ret
	.align ALIGNARG(4)
1:	fldpi
	fadd	%st(0)
	fxch	%st(1)
2:	fprem1
	fnstsw	%ax
	testl	$0x400,%eax
	jnz	2b
	fstp	%st(1)
	fsin
	ret
END (__sin)
weak_alias (__sin, sin)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj