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      1 /* s_tanf.c -- float version of s_tan.c.
      2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) cygnus.com.
      3  * Optimized by Bruce D. Evans.
      4  */
      5 
      6 /*
      7  * ====================================================
      8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
      9  *
     10  * Developed at SunPro, a Sun Microsystems, Inc. business.
     11  * Permission to use, copy, modify, and distribute this
     12  * software is freely granted, provided that this notice
     13  * is preserved.
     14  * ====================================================
     15  */
     16 
     17 #include <sys/cdefs.h>
     18 __FBSDID("$FreeBSD$");
     19 
     20 #include <float.h>
     21 
     22 #include "math.h"
     23 #define	INLINE_KERNEL_TANDF
     24 #define INLINE_REM_PIO2F
     25 #include "math_private.h"
     26 #include "e_rem_pio2f.c"
     27 #include "k_tanf.c"
     28 
     29 /* Small multiples of pi/2 rounded to double precision. */
     30 static const double
     31 t1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
     32 t2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
     33 t3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
     34 t4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
     35 
     36 float
     37 tanf(float x)
     38 {
     39 	double y;
     40 	int32_t n, hx, ix;
     41 
     42 	GET_FLOAT_WORD(hx,x);
     43 	ix = hx & 0x7fffffff;
     44 
     45 	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
     46 	    if(ix<0x39800000)		/* |x| < 2**-12 */
     47 		if(((int)x)==0) return x;	/* x with inexact if x != 0 */
     48 	    return __kernel_tandf(x,1);
     49 	}
     50 	if(ix<=0x407b53d1) {		/* |x| ~<= 5*pi/4 */
     51 	    if(ix<=0x4016cbe3)		/* |x| ~<= 3pi/4 */
     52 		return __kernel_tandf(x + (hx>0 ? -t1pio2 : t1pio2), -1);
     53 	    else
     54 		return __kernel_tandf(x + (hx>0 ? -t2pio2 : t2pio2), 1);
     55 	}
     56 	if(ix<=0x40e231d5) {		/* |x| ~<= 9*pi/4 */
     57 	    if(ix<=0x40afeddf)		/* |x| ~<= 7*pi/4 */
     58 		return __kernel_tandf(x + (hx>0 ? -t3pio2 : t3pio2), -1);
     59 	    else
     60 		return __kernel_tandf(x + (hx>0 ? -t4pio2 : t4pio2), 1);
     61 	}
     62 
     63     /* tan(Inf or NaN) is NaN */
     64 	else if (ix>=0x7f800000) return x-x;
     65 
     66     /* general argument reduction needed */
     67 	else {
     68 	    n = __ieee754_rem_pio2f(x,&y);
     69 	    /* integer parameter: 1 -- n even; -1 -- n odd */
     70 	    return __kernel_tandf(y,1-((n&1)<<1));
     71 	}
     72 }
     73