mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-20 05:42:34 +03:00
90 lines
2.0 KiB
C
90 lines
2.0 KiB
C
|
/* ef_sqrtf.c -- float version of e_sqrt.c.
|
||
|
|
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* ====================================================
|
||
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
||
|
|
*
|
||
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
||
|
|
* Permission to use, copy, modify, and distribute this
|
||
|
|
* software is freely granted, provided that this notice
|
||
|
|
* is preserved.
|
||
|
|
* ====================================================
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "fdlibm.h"
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
static const float one = 1.0, tiny=1.0e-30;
|
||
|
|
#else
|
||
|
|
static float one = 1.0, tiny=1.0e-30;
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
float __ieee754_sqrtf(float x)
|
||
|
|
#else
|
||
|
|
float __ieee754_sqrtf(x)
|
||
|
|
float x;
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
float z;
|
||
|
|
__uint32_t r,hx;
|
||
|
|
__int32_t ix,s,q,m,t,i;
|
||
|
|
|
||
|
|
GET_FLOAT_WORD(ix,x);
|
||
|
|
hx = ix&0x7fffffff;
|
||
|
|
|
||
|
|
/* take care of Inf and NaN */
|
||
|
|
if(!FLT_UWORD_IS_FINITE(hx))
|
||
|
|
return x*x+x; /* sqrt(NaN)=NaN, sqrt(+inf)=+inf
|
||
|
|
sqrt(-inf)=sNaN */
|
||
|
|
/* take care of zero and -ves */
|
||
|
|
if(FLT_UWORD_IS_ZERO(hx)) return x;/* sqrt(+-0) = +-0 */
|
||
|
|
if(ix<0) return (x-x)/(x-x); /* sqrt(-ve) = sNaN */
|
||
|
|
|
||
|
|
/* normalize x */
|
||
|
|
m = (ix>>23);
|
||
|
|
if(FLT_UWORD_IS_SUBNORMAL(hx)) { /* subnormal x */
|
||
|
|
for(i=0;(ix&0x00800000L)==0;i++) ix<<=1;
|
||
|
|
m -= i-1;
|
||
|
|
}
|
||
|
|
m -= 127; /* unbias exponent */
|
||
|
|
ix = (ix&0x007fffffL)|0x00800000L;
|
||
|
|
if(m&1) /* odd m, double x to make it even */
|
||
|
|
ix += ix;
|
||
|
|
m >>= 1; /* m = [m/2] */
|
||
|
|
|
||
|
|
/* generate sqrt(x) bit by bit */
|
||
|
|
ix += ix;
|
||
|
|
q = s = 0; /* q = sqrt(x) */
|
||
|
|
r = 0x01000000L; /* r = moving bit from right to left */
|
||
|
|
|
||
|
|
while(r!=0) {
|
||
|
|
t = s+r;
|
||
|
|
if(t<=ix) {
|
||
|
|
s = t+r;
|
||
|
|
ix -= t;
|
||
|
|
q += r;
|
||
|
|
}
|
||
|
|
ix += ix;
|
||
|
|
r>>=1;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* use floating add to find out rounding direction */
|
||
|
|
if(ix!=0) {
|
||
|
|
z = one-tiny; /* trigger inexact flag */
|
||
|
|
if (z>=one) {
|
||
|
|
z = one+tiny;
|
||
|
|
if (z>one)
|
||
|
|
q += 2;
|
||
|
|
else
|
||
|
|
q += (q&1);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
ix = (q>>1)+0x3f000000L;
|
||
|
|
ix += (m <<23);
|
||
|
|
SET_FLOAT_WORD(z,ix);
|
||
|
|
return z;
|
||
|
|
}
|