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/* e_rem_pio2f.c -- float version of e_rem_pio2.c
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
* Debugged and optimized by Bruce D. Evans.
*/
/*
* ====================================================
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/* __ieee754_rem_pio2f(x,y)
*
* return the remainder of x rem pi/2 in y[0]+y[1]
* use double precision internally
* use __kernel_rem_pio2() for large x
*/
#include <float.h>
#include "math.h"
#include "math_private.h"
/*
* invpio2: 53 bits of 2/pi
* pio2_1: first 33 bit of pi/2
* pio2_1t: pi/2 - pio2_1
*/
static const double
half = 5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */
invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
pio2_1 = 1.57079632673412561417e+00, /* 0x3FF921FB, 0x54400000 */
pio2_1t = 6.07710050650619224932e-11; /* 0x3DD0B461, 0x1A626331 */
int
__ieee754_rem_pio2f(float x, float *y)
{
double w,r,fn;
double tx[1],ty[2];
float z;
int32_t e0,n,ix,hx;
GET_FLOAT_WORD(hx,x);
ix = hx&0x7fffffff;
/* 33+53 bit pi is good enough for medium size */
if(ix<=0x49490f80) { /* |x| ~<= 2^19*(pi/2), medium size */
/* Use a specialized rint() to get fn. Assume round-to-nearest. */
STRICT_ASSIGN(double,fn,x*invpio2+0x1.8p52);
fn = fn-0x1.8p52;
#ifdef HAVE_EFFICIENT_IRINT
n = irint(fn);
#else
n = (int32_t)fn;
#endif
r = x-fn*pio2_1;
w = fn*pio2_1t;
y[0] = r-w;
y[1] = (r-y[0])-w;
return n;
}
/*
* all other (large) arguments
*/
if(ix>=0x7f800000) { /* x is inf or NaN */
y[0]=y[1]=x-x; return 0;
}
/* set z = scalbn(|x|,ilogb(|x|)-23) */
e0 = (ix>>23)-150; /* e0 = ilogb(|x|)-23; */
SET_FLOAT_WORD(z, ix - ((int32_t)(e0<<23)));
tx[0] = z;
n = __kernel_rem_pio2(tx,ty,e0,1,1);
y[0] = ty[0];
y[1] = ty[0] - y[0];
if(hx<0) {y[0] = -y[0]; y[1] = -y[1]; return -n;}
return n;
}
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