OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [newlib/] [libm/] [math/] [ef_acos.c] - Blame information for rev 855

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 148 jeremybenn
/* ef_acos.c -- float version of e_acos.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
#include "fdlibm.h"
17
 
18
#ifdef __STDC__
19
static const float
20
#else
21
static float
22
#endif
23
one =  1.0000000000e+00, /* 0x3F800000 */
24
pi =  3.1415925026e+00, /* 0x40490fda */
25
pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
26
pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
27
pS0 =  1.6666667163e-01, /* 0x3e2aaaab */
28
pS1 = -3.2556581497e-01, /* 0xbea6b090 */
29
pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
30
pS3 = -4.0055535734e-02, /* 0xbd241146 */
31
pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
32
pS5 =  3.4793309169e-05, /* 0x3811ef08 */
33
qS1 = -2.4033949375e+00, /* 0xc019d139 */
34
qS2 =  2.0209457874e+00, /* 0x4001572d */
35
qS3 = -6.8828397989e-01, /* 0xbf303361 */
36
qS4 =  7.7038154006e-02; /* 0x3d9dc62e */
37
 
38
#ifdef __STDC__
39
        float __ieee754_acosf(float x)
40
#else
41
        float __ieee754_acosf(x)
42
        float x;
43
#endif
44
{
45
        float z,p,q,r,w,s,c,df;
46
        __int32_t hx,ix;
47
        GET_FLOAT_WORD(hx,x);
48
        ix = hx&0x7fffffff;
49
        if(ix==0x3f800000) {            /* |x|==1 */
50
            if(hx>0) return 0.0; /* acos(1) = 0  */
51
            else return pi+(float)2.0*pio2_lo;  /* acos(-1)= pi */
52
        } else if(ix>0x3f800000) {      /* |x| >= 1 */
53
            return (x-x)/(x-x);         /* acos(|x|>1) is NaN */
54
        }
55
        if(ix<0x3f000000) {     /* |x| < 0.5 */
56
            if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
57
            z = x*x;
58
            p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
59
            q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
60
            r = p/q;
61
            return pio2_hi - (x - (pio2_lo-x*r));
62
        } else  if (hx<0) {              /* x < -0.5 */
63
            z = (one+x)*(float)0.5;
64
            p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
65
            q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
66
            s = __ieee754_sqrtf(z);
67
            r = p/q;
68
            w = r*s-pio2_lo;
69
            return pi - (float)2.0*(s+w);
70
        } else {                        /* x > 0.5 */
71
            __int32_t idf;
72
            z = (one-x)*(float)0.5;
73
            s = __ieee754_sqrtf(z);
74
            df = s;
75
            GET_FLOAT_WORD(idf,df);
76
            SET_FLOAT_WORD(df,idf&0xfffff000);
77
            c  = (z-df*df)/(s+df);
78
            p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
79
            q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
80
            r = p/q;
81
            w = r*s+c;
82
            return (float)2.0*(df+w);
83
        }
84
}

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.