GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libm/src/s_tanl.c Lines: 0 26 0.0 %
Date: 2017-11-13 Branches: 0 13 0.0 %

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/*	$OpenBSD: s_tanl.c,v 1.1 2008/12/09 20:00:35 martynas Exp $	*/
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/*-
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 * Copyright (c) 2007 Steven G. Kargl
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice unmodified, this list of conditions, and the following
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 *    disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/*
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 * Compute tan(x) for x where x is reduced to y = x - k * pi / 2.
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 * Limited testing on pseudorandom numbers drawn within [0:4e8] shows
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 * an accuracy of <= 1.5 ULP where 247024 values of x out of 40 million
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 * possibles resulted in tan(x) that exceeded 0.5 ULP (ie., 0.6%).
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 */
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#include <sys/types.h>
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#include <machine/ieee.h>
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#include <float.h>
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#include <math.h>
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#include "math_private.h"
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#if LDBL_MANT_DIG == 64
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#define	NX	3
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#define	PREC	2
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#elif LDBL_MANT_DIG == 113
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#define	NX	5
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#define	PREC	3
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#else
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#error "Unsupported long double format"
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#endif
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static const long double two24 = 1.67772160000000000000e+07L;
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long double
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tanl(long double x)
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{
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	union {
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		long double e;
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		struct ieee_ext bits;
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	} z;
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	int i, e0, s;
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	double xd[NX], yd[PREC];
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	long double hi, lo;
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	z.e = x;
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	s = z.bits.ext_sign;
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	z.bits.ext_sign = 0;
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	/* If x = +-0 or x is subnormal, then tan(x) = x. */
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	if (z.bits.ext_exp == 0)
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		return (x);
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	/* If x = NaN or Inf, then tan(x) = NaN. */
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	if (z.bits.ext_exp == 32767)
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		return ((x - x) / (x - x));
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	/* Optimize the case where x is already within range. */
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	if (z.e < M_PI_4) {
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		hi = __kernel_tanl(z.e, 0, 0);
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		return (s ? -hi : hi);
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	}
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	/* Split z.e into a 24-bit representation. */
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	e0 = ilogbl(z.e) - 23;
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	z.e = scalbnl(z.e, -e0);
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	for (i = 0; i < NX; i++) {
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		xd[i] = (double)((int32_t)z.e);
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		z.e = (z.e - xd[i]) * two24;
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	}
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	/* yd contains the pieces of xd rem pi/2 such that |yd| < pi/4. */
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	e0 = __kernel_rem_pio2(xd, yd, e0, NX, PREC);
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#if PREC == 2
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	hi = (long double)yd[0] + yd[1];
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	lo = yd[1] - (hi - yd[0]);
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#else /* PREC == 3 */
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	long double t;
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	t = (long double)yd[2] + yd[1];
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	hi = t + yd[0];
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	lo = yd[0] - (hi - t);
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#endif
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	switch (e0 & 3) {
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	case 0:
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	case 2:
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	    hi = __kernel_tanl(hi, lo, 0);
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	    break;
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	case 1:
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	case 3:
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	    hi = __kernel_tanl(hi, lo, 1);
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	    break;
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	}
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	return (s ? -hi : hi);
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}