s_tanf.cpp (2006B)
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 <sys/cdefs.h> 18 //__FBSDID("$FreeBSD$"); 19 20 #include <float.h> 21 22 #define INLINE_KERNEL_TANDF 23 #define INLINE_REM_PIO2F 24 #include "math_private.h" 25 #include "e_rem_pio2f.cpp" 26 #include "k_tanf.cpp" 27 28 /* Small multiples of pi/2 rounded to double precision. */ 29 static const double 30 t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ 31 t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ 32 t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ 33 t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ 34 35 float 36 tanf(float x) 37 { 38 double y; 39 int32_t n, hx, ix; 40 41 GET_FLOAT_WORD(hx,x); 42 ix = hx & 0x7fffffff; 43 44 if(ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ 45 if(ix<0x39800000) /* |x| < 2**-12 */ 46 if(((int)x)==0) return x; /* x with inexact if x != 0 */ 47 return __kernel_tandf(x,1); 48 } 49 if(ix<=0x407b53d1) { /* |x| ~<= 5*pi/4 */ 50 if(ix<=0x4016cbe3) /* |x| ~<= 3pi/4 */ 51 return __kernel_tandf(x + (hx>0 ? -t1pio2 : t1pio2), -1); 52 else 53 return __kernel_tandf(x + (hx>0 ? -t2pio2 : t2pio2), 1); 54 } 55 if(ix<=0x40e231d5) { /* |x| ~<= 9*pi/4 */ 56 if(ix<=0x40afeddf) /* |x| ~<= 7*pi/4 */ 57 return __kernel_tandf(x + (hx>0 ? -t3pio2 : t3pio2), -1); 58 else 59 return __kernel_tandf(x + (hx>0 ? -t4pio2 : t4pio2), 1); 60 } 61 62 /* tan(Inf or NaN) is NaN */ 63 else if (ix>=0x7f800000) return x-x; 64 65 /* general argument reduction needed */ 66 else { 67 n = __ieee754_rem_pio2f(x,&y); 68 /* integer parameter: 1 -- n even; -1 -- n odd */ 69 return __kernel_tandf(y,1-((n&1)<<1)); 70 } 71 }