65 lines
1.7 KiB
C
65 lines
1.7 KiB
C
/* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */
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/*
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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* Optimized by Bruce D. Evans.
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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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#include "libc/math/libm.h"
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/* Small multiples of pi/2 rounded to double precision. */
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static const double
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t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
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t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
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t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
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t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
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float tanf(float x)
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{
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double y;
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uint32_t ix;
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unsigned n, sign;
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GET_FLOAT_WORD(ix, x);
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sign = ix >> 31;
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ix &= 0x7fffffff;
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if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */
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if (ix < 0x39800000) { /* |x| < 2**-12 */
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/* raise inexact if x!=0 and underflow if subnormal */
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FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f);
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return x;
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}
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return __tandf(x, 0);
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}
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if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */
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if (ix <= 0x4016cbe3) /* |x| ~<= 3pi/4 */
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return __tandf((sign ? x+t1pio2 : x-t1pio2), 1);
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else
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return __tandf((sign ? x+t2pio2 : x-t2pio2), 0);
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}
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if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */
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if (ix <= 0x40afeddf) /* |x| ~<= 7*pi/4 */
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return __tandf((sign ? x+t3pio2 : x-t3pio2), 1);
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else
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return __tandf((sign ? x+t4pio2 : x-t4pio2), 0);
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}
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/* tan(Inf or NaN) is NaN */
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if (ix >= 0x7f800000)
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return x - x;
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/* argument reduction */
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n = __rem_pio2f(x, &y);
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return __tandf(y, n&1);
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}
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