| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 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 | #ifndef lint |
| 18 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_tanf.c,v 1.14 2005/11/28 05:35:32 bde Exp $"; |
| 19 | #endif |
| 20 | |
| 21 | #include "math.h" |
| 22 | #define INLINE_KERNEL_TANDF |
| 23 | #include "math_private.h" |
| 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 |
| 34 | tanf(float x) |
| 35 | { |
| 36 | float y[2]; |
| 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((double)y[0]+y[1],1-((n&1)<<1)); |
| 68 | } |
| 69 | } |