1 /* s_tanf.c -- float version of s_tan.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #ifndef lint 17 static char rcsid[] = "$FreeBSD$"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 /* Small multiples of pi/2 rounded to double precision. */ 24 static const double 25 t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ 26 t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ 27 t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ 28 t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ 29 30 static inline float 31 __kernel_tandf(double x, int iy) 32 { 33 return __kernel_tanf((float)x, x - (float)x, iy); 34 } 35 36 float 37 tanf(float x) 38 { 39 float y[2],z=0.0; 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_tanf(x,z,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_tanf(y[0],y[1],1-((n&1)<<1)); 71 } 72 } 73