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e_acosf.c
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/* e_acosf.c -- float version of e_acos.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, [email protected].
*/
/*
* ====================================================
* 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.
* ====================================================
*/
#ifndef __FDLIBM_H__
#include "fdlibm.h"
#endif
#ifndef __have_fpu_acos
float __ieee754_acosf(float x)
{
float z, p, q, r, w, s, c, df;
int32_t hx, ix;
static const float one = 1.0000000000e+00; /* 0x3F800000 */
static const float pi = 3.1415925026e+00; /* 0x40490fda */
static const float pio2_hi = 1.5707962513e+00; /* 0x3fc90fda */
static const float pio2_lo = 7.5497894159e-08; /* 0x33a22168 */
static const float pS0 = 1.6666667163e-01; /* 0x3e2aaaab */
static const float pS1 = -3.2556581497e-01; /* 0xbea6b090 */
static const float pS2 = 2.0121252537e-01; /* 0x3e4e0aa8 */
static const float pS3 = -4.0055535734e-02; /* 0xbd241146 */
static const float pS4 = 7.9153501429e-04; /* 0x3a4f7f04 */
static const float pS5 = 3.4793309169e-05; /* 0x3811ef08 */
static const float qS1 = -2.4033949375e+00; /* 0xc019d139 */
static const float qS2 = 2.0209457874e+00; /* 0x4001572d */
static const float qS3 = -6.8828397989e-01; /* 0xbf303361 */
static const float qS4 = 7.7038154006e-02; /* 0x3d9dc62e */
GET_FLOAT_WORD(hx, x);
ix = hx & IC(0x7fffffff);
if (ix == IC(0x3f800000))
{ /* |x|==1 */
if (hx > 0)
return 0.0; /* acos(1) = 0 */
else
return pi + 2.0f * pio2_lo; /* acos(-1)= pi */
} else if (ix > IC(0x3f800000))
{ /* |x| >= 1 */
return (x - x) / (x - x); /* acos(|x|>1) is NaN */
}
if (ix < IC(0x3f000000))
{ /* |x| < 0.5 */
if (ix <= IC(0x32800000))
return pio2_hi + pio2_lo; /*if|x|<=2**-26 */
z = x * x;
p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
q = one + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
r = p / q;
return pio2_hi - (x - (pio2_lo - x * r));
} else if (hx < 0)
{ /* x < -0.5 */
z = (one + x) * 0.5f;
p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
q = one + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
s = __ieee754_sqrtf(z);
r = p / q;
w = r * s - pio2_lo;
return pi - 2.0f * (s + w);
} else
{ /* x > 0.5 */
int32_t idf;
z = (one - x) * 0.5f;
s = __ieee754_sqrtf(z);
df = s;
GET_FLOAT_WORD(idf, df);
SET_FLOAT_WORD(df, idf & IC(0xfffff000));
c = (z - df * df) / (s + df);
p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
q = one + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
r = p / q;
w = r * s + c;
return 2.0f * (df + w);
}
}
#endif
/* wrapper acosf */
float __acosf(float x)
{
if (isgreater(__ieee754_fabsf(x), 1.0f) && _LIB_VERSION != _IEEE_)
{
/* acos(|x|>1) */
feraiseexcept(FE_INVALID);
return __kernel_standard_f(x, x, __builtin_nanf(""), KMATHERRF_ACOS);
}
return __ieee754_acosf(x);
}
__typeof(__acosf) acosf __attribute__((weak, alias("__acosf")));