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/* s_tanf.c -- float version of s_tan.c.
*/
/*
* ====================================================
* 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.
* ====================================================
*/
#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_tanf.c,v 1.4 1995/05/10 20:48:20 jtc Exp $";
#endif
#include <errno.h>
#include <math.h>
#include <math_private.h>
#include <libm-alias-float.h>
#include "s_sincosf.h"
/* Reduce range of X to a multiple of PI/2. The modulo result is between
-PI/4 and PI/4 and returned as a high part y[0] and a low part y[1].
The low bit in the return value indicates the first or 2nd half of tanf. */
static inline int32_t
rem_pio2f (float x, float *y)
{
double dx = x;
int n;
const sincos_t *p = &__sincosf_table[0];
if (__glibc_likely (abstop12 (x) < abstop12 (120.0f)))
dx = reduce_fast (dx, p, &n);
else
{
uint32_t xi = asuint (x);
int sign = xi >> 31;
dx = reduce_large (xi, &n);
dx = sign ? -dx : dx;
}
y[0] = dx;
y[1] = dx - y[0];
return n;
}
float __tanf(float x)
{
float y[2],z=0.0;
int32_t n, ix;
GET_FLOAT_WORD(ix,x);
/* |x| ~< pi/4 */
ix &= 0x7fffffff;
if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
/* tan(Inf or NaN) is NaN */
else if (ix>=0x7f800000) {
if (ix==0x7f800000)
__set_errno (EDOM);
return x-x; /* NaN */
}
/* argument reduction needed */
else {
n = rem_pio2f(x,y);
return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even
-1 -- n odd */
}
}
libm_alias_float (__tan, tan)
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