a0ee07829a
This brings us up to date with FreeBSD HEAD, fixes various bugs, unifies the set of functions we support on ARM, MIPS, and x86, fixes "long double", adds ISO C99 support, and adds basic unit tests. It turns out that our "long double" functions have always been broken for non-normal numbers. This patch fixes that by not using the upstream implementations and just forwarding to the regular "double" implementation instead (since "long double" on Android is just "double" anyway, which is what BSD doesn't support). All the tests pass on ARM, MIPS, and x86, plus glibc on x86-64. Bug: 3169850 Bug: 8012787 Bug: https://code.google.com/p/android/issues/detail?id=6697 Change-Id: If0c343030959c24bfc50d4d21c9530052c581837
86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/* @(#)s_atan.c 5.1 93/09/24 */
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/* FreeBSD: head/lib/msun/src/s_atan.c 176451 2008-02-22 02:30:36Z das */
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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 SunPro, 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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*
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* See comments in s_atan.c.
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* Converted to long double by David Schultz <das@FreeBSD.ORG>.
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*/
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#include <float.h>
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#include "invtrig.h"
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#include "math.h"
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#include "math_private.h"
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static const long double
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one = 1.0,
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huge = 1.0e300;
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long double
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atanl(long double x)
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{
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union IEEEl2bits u;
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long double w,s1,s2,z;
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int id;
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int16_t expsign, expt;
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int32_t expman;
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u.e = x;
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expsign = u.xbits.expsign;
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expt = expsign & 0x7fff;
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if(expt >= ATAN_CONST) { /* if |x| is large, atan(x)~=pi/2 */
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if(expt == BIAS + LDBL_MAX_EXP &&
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((u.bits.manh&~LDBL_NBIT)|u.bits.manl)!=0)
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return x+x; /* NaN */
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if(expsign>0) return atanhi[3]+atanlo[3];
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else return -atanhi[3]-atanlo[3];
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}
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/* Extract the exponent and the first few bits of the mantissa. */
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/* XXX There should be a more convenient way to do this. */
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expman = (expt << 8) | ((u.bits.manh >> (MANH_SIZE - 9)) & 0xff);
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if (expman < ((BIAS - 2) << 8) + 0xc0) { /* |x| < 0.4375 */
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if (expt < ATAN_LINEAR) { /* if |x| is small, atanl(x)~=x */
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if(huge+x>one) return x; /* raise inexact */
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}
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id = -1;
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} else {
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x = fabsl(x);
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if (expman < (BIAS << 8) + 0x30) { /* |x| < 1.1875 */
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if (expman < ((BIAS - 1) << 8) + 0x60) { /* 7/16 <=|x|<11/16 */
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id = 0; x = (2.0*x-one)/(2.0+x);
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} else { /* 11/16<=|x|< 19/16 */
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id = 1; x = (x-one)/(x+one);
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}
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} else {
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if (expman < ((BIAS + 1) << 8) + 0x38) { /* |x| < 2.4375 */
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id = 2; x = (x-1.5)/(one+1.5*x);
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} else { /* 2.4375 <= |x| < 2^ATAN_CONST */
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id = 3; x = -1.0/x;
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}
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}}
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/* end of argument reduction */
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z = x*x;
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w = z*z;
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/* break sum aT[i]z**(i+1) into odd and even poly */
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s1 = z*T_even(w);
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s2 = w*T_odd(w);
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if (id<0) return x - x*(s1+s2);
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else {
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z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x);
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return (expsign<0)? -z:z;
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}
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}
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