77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
/* s_tanf.c -- float version of s_tan.c.
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*/
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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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: s_tanf.c,v 1.4 1995/05/10 20:48:20 jtc Exp $";
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#endif
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#include <errno.h>
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#include <math.h>
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#include <math_private.h>
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#include <libm-alias-float.h>
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#include "s_sincosf.h"
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/* Reduce range of X to a multiple of PI/2. The modulo result is between
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-PI/4 and PI/4 and returned as a high part y[0] and a low part y[1].
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The low bit in the return value indicates the first or 2nd half of tanf. */
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static inline int32_t
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rem_pio2f (float x, float *y)
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{
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double dx = x;
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int n;
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const sincos_t *p = &__sincosf_table[0];
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if (__glibc_likely (abstop12 (x) < abstop12 (120.0f)))
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dx = reduce_fast (dx, p, &n);
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else
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{
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uint32_t xi = asuint (x);
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int sign = xi >> 31;
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dx = reduce_large (xi, &n);
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dx = sign ? -dx : dx;
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}
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y[0] = dx;
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y[1] = dx - y[0];
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return n;
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}
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float __tanf(float x)
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{
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float y[2],z=0.0;
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int32_t n, ix;
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GET_FLOAT_WORD(ix,x);
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/* |x| ~< pi/4 */
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ix &= 0x7fffffff;
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if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
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/* tan(Inf or NaN) is NaN */
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else if (ix>=0x7f800000) {
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if (ix==0x7f800000)
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__set_errno (EDOM);
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return x-x; /* NaN */
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}
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/* argument reduction needed */
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else {
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n = rem_pio2f(x,y);
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return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even
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-1 -- n odd */
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}
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}
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libm_alias_float (__tan, tan)
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