/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-â
âvi: set et ft=c ts=8 tw=8 fenc=utf-8                                       :viâ
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â                                                                              â
â  Musl Libc                                                                   â
â  Copyright Â© 2005-2020 Rich Felker, et al.                                   â
â                                                                              â
â  Permission is hereby granted, free of charge, to any person obtaining       â
â  a copy of this software and associated documentation files (the             â
â  "Software"), to deal in the Software without restriction, including         â
â  without limitation the rights to use, copy, modify, merge, publish,         â
â  distribute, sublicense, and/or sell copies of the Software, and to          â
â  permit persons to whom the Software is furnished to do so, subject to       â
â  the following conditions:                                                   â
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â  The above copyright notice and this permission notice shall be              â
â  included in all copies or substantial portions of the Software.             â
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â  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             â
â  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          â
â  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      â
â  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        â
â  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        â
â  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           â
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â                                                                              â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#include "libc/math.h"
#include "libc/tinymath/complex.internal.h"

asm(".ident\t\"\\n\\n\
fdlibm (fdlibm license)\\n\
Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\"");
asm(".ident\t\"\\n\\n\
Musl libc (MIT License)\\n\
Copyright 2005-2014 Rich Felker, et. al.\"");
asm(".include \"libc/disclaimer.inc\"");
// clang-format off

/* origin: FreeBSD /usr/src/lib/msun/src/e_asinf.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.
 * ====================================================
 */

static const double
pio2 = 1.570796326794896558e+00;

static const float
/* coefficients for R(x^2) */
pS0 =  1.6666586697e-01,
pS1 = -4.2743422091e-02,
pS2 = -8.6563630030e-03,
qS1 = -7.0662963390e-01;

static float R(float z)
{
	float_t p, q;
	p = z*(pS0+z*(pS1+z*pS2));
	q = 1.0f+z*qS1;
	return p/q;
}

/**
 * Returns arc sine of ð¥.
 */
float asinf(float x)
{
	double s;
	float z;
	uint32_t hx,ix;

	GET_FLOAT_WORD(hx, x);
	ix = hx & 0x7fffffff;
	if (ix >= 0x3f800000) {  /* |x| >= 1 */
		if (ix == 0x3f800000)  /* |x| == 1 */
			return x*pio2 + 0x1p-120f;  /* asin(+-1) = +-pi/2 with inexact */
		return 0/(x-x);  /* asin(|x|>1) is NaN */
	}
	if (ix < 0x3f000000) {  /* |x| < 0.5 */
		/* if 0x1p-126 <= |x| < 0x1p-12, avoid raising underflow */
		if (ix < 0x39800000 && ix >= 0x00800000)
			return x;
		return x + x*R(x*x);
	}
	/* 1 > |x| >= 0.5 */
	z = (1 - fabsf(x))*0.5f;
	s = sqrt(z);
	x = pio2 - 2*(s+s*R(z));
	if (hx >> 31)
		return -x;
	return x;
}
