1 /* s_tanf.c -- float version of s_tan.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@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 <float.h>
18
19 #include "math.h"
20 #define INLINE_KERNEL_TANDF
21 #define INLINE_REM_PIO2F
22 #include "math_private.h"
23 #include "e_rem_pio2f.c"
24 #include "k_tanf.c"
25
26 /* Small multiples of pi/2 rounded to double precision. */
27 static const double
28 t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
29 t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
30 t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
31 t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
32
33 float
tanf(float x)34 tanf(float x)
35 {
36 double y;
37 int32_t n, hx, ix;
38
39 GET_FLOAT_WORD(hx,x);
40 ix = hx & 0x7fffffff;
41
42 if(ix <= 0x3f490fda) { /* |x| ~<= pi/4 */
43 if(ix<0x39800000) /* |x| < 2**-12 */
44 if(((int)x)==0) return x; /* x with inexact if x != 0 */
45 return __kernel_tandf(x,1);
46 }
47 if(ix<=0x407b53d1) { /* |x| ~<= 5*pi/4 */
48 if(ix<=0x4016cbe3) /* |x| ~<= 3pi/4 */
49 return __kernel_tandf(x + (hx>0 ? -t1pio2 : t1pio2), -1);
50 else
51 return __kernel_tandf(x + (hx>0 ? -t2pio2 : t2pio2), 1);
52 }
53 if(ix<=0x40e231d5) { /* |x| ~<= 9*pi/4 */
54 if(ix<=0x40afeddf) /* |x| ~<= 7*pi/4 */
55 return __kernel_tandf(x + (hx>0 ? -t3pio2 : t3pio2), -1);
56 else
57 return __kernel_tandf(x + (hx>0 ? -t4pio2 : t4pio2), 1);
58 }
59
60 /* tan(Inf or NaN) is NaN */
61 else if (ix>=0x7f800000) return x-x;
62
63 /* general argument reduction needed */
64 else {
65 n = __ieee754_rem_pio2f(x,&y);
66 /* integer parameter: 1 -- n even; -1 -- n odd */
67 return __kernel_tandf(y,1-((n&1)<<1));
68 }
69 }
70