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 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