79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.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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c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
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c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
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c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
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c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
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float cosf(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 */
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FORCE_EVAL(x + 0x1p120f);
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return 1.0f;
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}
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return __cosdf(x);
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}
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if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */
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if (ix > 0x4016cbe3) /* |x| ~> 3*pi/4 */
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return -__cosdf(sign ? x+c2pio2 : x-c2pio2);
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else {
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if (sign)
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return __sindf(x + c1pio2);
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else
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return __sindf(c1pio2 - x);
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}
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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 __cosdf(sign ? x+c4pio2 : x-c4pio2);
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else {
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if (sign)
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return __sindf(-x - c3pio2);
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else
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return __sindf(x - c3pio2);
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}
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}
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/* cos(Inf or NaN) is NaN */
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if (ix >= 0x7f800000)
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return x-x;
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/* general argument reduction needed */
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n = __rem_pio2f(x,&y);
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switch (n&3) {
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case 0: return __cosdf(y);
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case 1: return __sindf(-y);
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case 2: return -__cosdf(y);
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default:
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return __sindf(y);
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}
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}
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