| /* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */ |
| /* |
| * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
| * Optimized by Bruce D. Evans. |
| */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| #include "libm.h" |
| |
| /* Small multiples of pi/2 rounded to double precision. */ |
| static const double |
| t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ |
| t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ |
| t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ |
| t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ |
| |
| float tanf(float x) |
| { |
| double y; |
| uint32_t ix; |
| unsigned n, sign; |
| |
| GET_FLOAT_WORD(ix, x); |
| sign = ix >> 31; |
| ix &= 0x7fffffff; |
| |
| if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ |
| if (ix < 0x39800000) { /* |x| < 2**-12 */ |
| /* raise inexact if x!=0 and underflow if subnormal */ |
| FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f); |
| return x; |
| } |
| return __tandf(x, 0); |
| } |
| if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ |
| if (ix <= 0x4016cbe3) /* |x| ~<= 3pi/4 */ |
| return __tandf((sign ? x+t1pio2 : x-t1pio2), 1); |
| else |
| return __tandf((sign ? x+t2pio2 : x-t2pio2), 0); |
| } |
| if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ |
| if (ix <= 0x40afeddf) /* |x| ~<= 7*pi/4 */ |
| return __tandf((sign ? x+t3pio2 : x-t3pio2), 1); |
| else |
| return __tandf((sign ? x+t4pio2 : x-t4pio2), 0); |
| } |
| |
| /* tan(Inf or NaN) is NaN */ |
| if (ix >= 0x7f800000) |
| return x - x; |
| |
| /* argument reduction */ |
| n = __rem_pio2f(x, &y); |
| return __tandf(y, n&1); |
| } |
