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Re: patch for e_remainder.c
- From: Carsten Langgaard <carstenl at mips dot com>
- To: moshier at moshier dot ne dot mediaone dot net
- Cc: libc-alpha at sources dot redhat dot com, "H . J . Lu" <hjl at lucon dot org>
- Date: Mon, 03 Dec 2001 10:45:28 +0100
- Subject: Re: patch for e_remainder.c
- References: <Pine.LNX.4.20.0112021520170.17520-100000@moshier.ne.mediaone.net>
Thanks a lot.
Have you every tried this IEEE compliant checker, it might be useful:
http://win-www.uia.ac.be/u/cant/ieeecc754.html
/Carsten
Stephen L Moshier wrote:
> The patch below is derived from a repaired version of urem.c communicated
> by Moshe Olshansky <OLSHANSK@il.ibm.com>, one of the authors.
> To create the patch I merged his change into the glibc version of the file.
>
> Moshe Olshansky <OLSHANSK@il.ibm.com>
> * sysdeps/ieee754/dbl-64/e_remainder.c (__ieee754_remainder):
> Fix overflow problem.
>
> *** e_remainder.c 2001/05/12 14:31:44 1.1
> --- e_remainder.c 2001/12/02 20:10:08
> *************** double __ieee754_remainder(double x, dou
> *** 55,62 ****
> kx=u.i[HIGH_HALF]&0x7fffffff; /* no sign for x*/
> t.i[HIGH_HALF]&=0x7fffffff; /*no sign for y */
> ky=t.i[HIGH_HALF];
> ! /*------ |x| < 2^1024 and 2^-970 < |y| < 2^1024 ------------------*/
> ! if (kx<0x7ff00000 && ky<0x7ff00000 && ky>=0x03500000) {
> if (kx+0x00100000<ky) return x;
> if ((kx-0x01500000)<ky) {
> z=x/t.x;
> --- 55,62 ----
> kx=u.i[HIGH_HALF]&0x7fffffff; /* no sign for x*/
> t.i[HIGH_HALF]&=0x7fffffff; /*no sign for y */
> ky=t.i[HIGH_HALF];
> ! /*------ |x| < 2^1023 and 2^-970 < |y| < 2^1024 ------------------*/
> ! if (kx<0x7fe00000 && ky<0x7ff00000 && ky>=0x03500000) {
> if (kx+0x00100000<ky) return x;
> if ((kx-0x01500000)<ky) {
> z=x/t.x;
> *************** double __ieee754_remainder(double x, dou
> *** 100,113 ****
> {z=u.x/t.x; d=(z+big.x)-big.x; return ((u.x-d*w.x)-d*ww.x);}
> }
>
> ! } /* (kx<0x7ff00000&&ky<0x7ff00000&&ky>=0x03500000) */
> else {
> ! if (kx<0x7ff00000&&ky<0x7ff00000&&(ky>0||t.i[LOW_HALF]!=0)) {
> y=ABS(y)*t128.x;
> z=__ieee754_remainder(x,y)*t128.x;
> z=__ieee754_remainder(z,y)*tm128.x;
> return z;
> }
> else { /* if x is too big */
> if (kx == 0x7ff00000 && u.i[LOW_HALF] == 0 && y == 1.0)
> return x / x;
> --- 100,121 ----
> {z=u.x/t.x; d=(z+big.x)-big.x; return ((u.x-d*w.x)-d*ww.x);}
> }
>
> ! } /* (kx<0x7fe00000&&ky<0x7ff00000&&ky>=0x03500000) */
> else {
> ! if (kx<0x7fe00000&&ky<0x7ff00000&&(ky>0||t.i[LOW_HALF]!=0)) {
> y=ABS(y)*t128.x;
> z=__ieee754_remainder(x,y)*t128.x;
> z=__ieee754_remainder(z,y)*tm128.x;
> return z;
> }
> + else {
> + if ((kx&0x7ff00000)==0x7fe00000&&ky<0x7ff00000&&(ky>0||t.i[LOW_HALF]!=0)) {
> + y=ABS(y);
> + z=2.0*__ieee754_remainder(0.5*x,y);
> + d = ABS(z);
> + if (d <= ABS(d-y)) return z;
> + else return (z>0)?z-y:z+y;
> + }
> else { /* if x is too big */
> if (kx == 0x7ff00000 && u.i[LOW_HALF] == 0 && y == 1.0)
> return x / x;
> *************** double __ieee754_remainder(double x, dou
> *** 116,120 ****
> --- 124,129 ----
> return (u.i[HIGH_HALF]&0x80000000)?nNAN.x:NAN.x;
> else return x;
> }
> + }
> }
> }
--
_ _ ____ ___ Carsten Langgaard Mailto:carstenl@mips.com
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