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alexbevi
GitHub Repository: alexbevi/BizHawk
 Path: blob/master/waterbox/libc/functions/math/asinl.c
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/* origin: FreeBSD /usr/src/lib/msun/src/e_asinl.c */

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/*

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 * ====================================================

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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

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 *

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 * Developed at SunSoft, a Sun Microsystems, Inc. business.

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 * Permission to use, copy, modify, and distribute this

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 * software is freely granted, provided that this notice

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 * is preserved.

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 * ====================================================

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 */

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/*

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 * See comments in asin.c.

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 * Converted to long double by David Schultz <[email protected]>.

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 */

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#include "libm.h"

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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024

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long double asinl(long double x)

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{

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	return asin(x);

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}

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#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384

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#include "__invtrigl.h"

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#if LDBL_MANT_DIG == 64

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#define CLOSETO1(u) (u.i.m>>56 >= 0xf7)

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#define CLEARBOTTOM(u) (u.i.m &= -1ULL << 32)

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#elif LDBL_MANT_DIG == 113

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#define CLOSETO1(u) (u.i.top >= 0xee00)

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#define CLEARBOTTOM(u) (u.i.lo = 0)

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#endif

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long double asinl(long double x)

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{

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	union ldshape u = {x};

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	long double z, r, s;

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	uint16_t e = u.i.se & 0x7fff;

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	int sign = u.i.se >> 15;

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	if (e >= 0x3fff) {   /* |x| >= 1 or nan */

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		/* asin(+-1)=+-pi/2 with inexact */

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		if (x == 1 || x == -1)

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			return x*pio2_hi + 0x1p-120f;

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		return 0/(x-x);

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	}

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	if (e < 0x3fff - 1) {  /* |x| < 0.5 */

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		if (e < 0x3fff - (LDBL_MANT_DIG+1)/2) {

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			/* return x with inexact if x!=0 */

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			FORCE_EVAL(x + 0x1p120f);

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			return x;

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		}

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		return x + x*__invtrigl_R(x*x);

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	}

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	/* 1 > |x| >= 0.5 */

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	z = (1.0 - fabsl(x))*0.5;

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	s = sqrtl(z);

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	r = __invtrigl_R(z);

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	if (CLOSETO1(u)) {

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		x = pio2_hi - (2*(s+s*r)-pio2_lo);

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	} else {

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		long double f, c;

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		u.f = s;

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		CLEARBOTTOM(u);

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		f = u.f;

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		c = (z - f*f)/(s + f);

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		x = 0.5*pio2_hi-(2*s*r - (pio2_lo-2*c) - (0.5*pio2_hi-2*f));

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	}

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	return sign ? -x : x;

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}

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#endif

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