| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 1 | /* s_cosf.c -- float version of s_cos.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_cosf.c,v 1.15 2005/11/30 06:47:18 bde Exp $"; |
| 19 | #endif |
| 20 | |
| 21 | #include "math.h" |
| 22 | #define INLINE_KERNEL_COSDF |
| 23 | #define INLINE_KERNEL_SINDF |
| 24 | #include "math_private.h" |
| 25 | #include "k_cosf.c" |
| 26 | #include "k_sinf.c" |
| 27 | |
| 28 | /* Small multiples of pi/2 rounded to double precision. */ |
| 29 | static const double |
| 30 | c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ |
| 31 | c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ |
| 32 | c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ |
| 33 | c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ |
| 34 | |
| 35 | float |
| 36 | cosf(float x) |
| 37 | { |
| 38 | float y[2]; |
| 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 1.0; /* 1 with inexact if x != 0 */ |
| 47 | return __kernel_cosdf(x); |
| 48 | } |
| 49 | if(ix<=0x407b53d1) { /* |x| ~<= 5*pi/4 */ |
| 50 | if(ix>0x4016cbe3) /* |x| ~> 3*pi/4 */ |
| 51 | return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2)); |
| 52 | else { |
| 53 | if(hx>0) |
| 54 | return __kernel_sindf(c1pio2 - x); |
| 55 | else |
| 56 | return __kernel_sindf(x + c1pio2); |
| 57 | } |
| 58 | } |
| 59 | if(ix<=0x40e231d5) { /* |x| ~<= 9*pi/4 */ |
| 60 | if(ix>0x40afeddf) /* |x| ~> 7*pi/4 */ |
| 61 | return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2)); |
| 62 | else { |
| 63 | if(hx>0) |
| 64 | return __kernel_sindf(x - c3pio2); |
| 65 | else |
| 66 | return __kernel_sindf(-c3pio2 - x); |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | /* cos(Inf or NaN) is NaN */ |
| 71 | else if (ix>=0x7f800000) return x-x; |
| 72 | |
| 73 | /* general argument reduction needed */ |
| 74 | else { |
| 75 | n = __ieee754_rem_pio2f(x,y); |
| 76 | switch(n&3) { |
| 77 | case 0: return __kernel_cosdf((double)y[0]+y[1]); |
| 78 | case 1: return __kernel_sindf(-(double)y[0]-y[1]); |
| 79 | case 2: return -__kernel_cosdf((double)y[0]+y[1]); |
| 80 | default: |
| 81 | return __kernel_sindf((double)y[0]+y[1]); |
| 82 | } |
| 83 | } |
| 84 | } |