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/* sf_log1p.c -- float version of s_log1p.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */
 
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */
 
#include "fdlibm.h"
 
#ifdef __STDC__
static const float
#else
static float
#endif
ln2_hi =   6.9313812256e-01,    /* 0x3f317180 */
ln2_lo =   9.0580006145e-06,    /* 0x3717f7d1 */
two25 =    3.355443200e+07,     /* 0x4c000000 */
Lp1 = 6.6666668653e-01, /* 3F2AAAAB */
Lp2 = 4.0000000596e-01, /* 3ECCCCCD */
Lp3 = 2.8571429849e-01, /* 3E924925 */
Lp4 = 2.2222198546e-01, /* 3E638E29 */
Lp5 = 1.8183572590e-01, /* 3E3A3325 */
Lp6 = 1.5313838422e-01, /* 3E1CD04F */
Lp7 = 1.4798198640e-01; /* 3E178897 */
 
#ifdef __STDC__
static const float zero = 0.0;
#else
static float zero = 0.0;
#endif
 
#ifdef __STDC__
        float log1pf(float x)
#else
        float log1pf(x)
        float x;
#endif
{
        float hfsq,f,c,s,z,R,u;
        __int32_t k,hx,hu,ax;
 
        GET_FLOAT_WORD(hx,x);
        ax = hx&0x7fffffff;
 
        k = 1;
        if (hx < 0x3ed413d7) {                  /* x < 0.41422  */
            if(ax>=0x3f800000) {                /* x <= -1.0 */
                if(x==(float)-1.0) return -two25/zero; /* log1p(-1)=+inf */
                else return (x-x)/(x-x);        /* log1p(x<-1)=NaN */
            }
            if(ax<0x31000000) {                 /* |x| < 2**-29 */
                if(two25+x>zero                 /* raise inexact */
                    &&ax<0x24800000)            /* |x| < 2**-54 */
                    return x;
                else
                    return x - x*x*(float)0.5;
            }
            if(hx>0||hx<=((__int32_t)0xbe95f61f)) {
                k=0;f=x;hu=1;}   /* -0.2929<x<0.41422 */
        }
        if (hx >= 0x7f800000) return x+x;
        if(k!=0) {
            if(hx<0x5a000000) {
                u  = (float)1.0+x;
                GET_FLOAT_WORD(hu,u);
                k  = (hu>>23)-127;
                /* correction term */
                c  = (k>0)? (float)1.0-(u-x):x-(u-(float)1.0);
                c /= u;
            } else {
                u  = x;
                GET_FLOAT_WORD(hu,u);
                k  = (hu>>23)-127;
                c  = 0;
            }
            hu &= 0x007fffff;
            if(hu<0x3504f7) {
                SET_FLOAT_WORD(u,hu|0x3f800000);/* normalize u */
            } else {
                k += 1;
                SET_FLOAT_WORD(u,hu|0x3f000000);        /* normalize u/2 */
                hu = (0x00800000-hu)>>2;
            }
            f = u-(float)1.0;
        }
        hfsq=(float)0.5*f*f;
        if(hu==0) {      /* |f| < 2**-20 */
            if(f==zero) if(k==0) return zero;
                        else {c += k*ln2_lo; return k*ln2_hi+c;}
            R = hfsq*((float)1.0-(float)0.66666666666666666*f);
            if(k==0) return f-R; else
                     return k*ln2_hi-((R-(k*ln2_lo+c))-f);
        }
        s = f/((float)2.0+f);
        z = s*s;
        R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7))))));
        if(k==0) return f-(hfsq-s*(hfsq+R)); else
                 return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f);
}
 
#ifdef _DOUBLE_IS_32BITS
 
#ifdef __STDC__
        double log1p(double x)
#else
        double log1p(x)
        double x;
#endif
{
        return (double) log1pf((float) x);
}
 
#endif /* defined(_DOUBLE_IS_32BITS) */

Line No.	Rev	Author	Line
1	39	lampret	`/* sf_log1p.c -- float version of s_log1p.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			`ln2_hi = 6.9313812256e-01, /* 0x3f317180 */`
24			`ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */`
25			`two25 = 3.355443200e+07, /* 0x4c000000 */`
26			`Lp1 = 6.6666668653e-01, /* 3F2AAAAB */`
27			`Lp2 = 4.0000000596e-01, /* 3ECCCCCD */`
28			`Lp3 = 2.8571429849e-01, /* 3E924925 */`
29			`Lp4 = 2.2222198546e-01, /* 3E638E29 */`
30			`Lp5 = 1.8183572590e-01, /* 3E3A3325 */`
31			`Lp6 = 1.5313838422e-01, /* 3E1CD04F */`
32			`Lp7 = 1.4798198640e-01; /* 3E178897 */`
33
34			`#ifdef __STDC__`
35			`static const float zero = 0.0;`
36			`#else`
37			`static float zero = 0.0;`
38			`#endif`
39
40			`#ifdef __STDC__`
41			`float log1pf(float x)`
42			`#else`
43			`float log1pf(x)`
44			`float x;`
45			`#endif`
46			`{`
47			`float hfsq,f,c,s,z,R,u;`
48			`__int32_t k,hx,hu,ax;`
49
50			`GET_FLOAT_WORD(hx,x);`
51			`ax = hx&0x7fffffff;`
52
53			`k = 1;`
54			`if (hx < 0x3ed413d7) { /* x < 0.41422 */`
55			`if(ax>=0x3f800000) { /* x <= -1.0 */`
56			`if(x==(float)-1.0) return -two25/zero; /* log1p(-1)=+inf */`
57			`else return (x-x)/(x-x); /* log1p(x<-1)=NaN */`
58			`}`
59			`if(ax<0x31000000) { /* \|x\| < 2*-29 /`
60			`if(two25+x>zero /* raise inexact */`
61			`&&ax<0x24800000) /* \|x\| < 2*-54 /`
62			`return x;`
63			`else`
64			`return x - xx(float)0.5;`
65			`}`
66			`if(hx>0\|\|hx<=((__int32_t)0xbe95f61f)) {`
67			`k=0;f=x;hu=1;} /* -0.2929<x<0.41422 */`
68			`}`
69			`if (hx >= 0x7f800000) return x+x;`
70			`if(k!=0) {`
71			`if(hx<0x5a000000) {`
72			`u = (float)1.0+x;`
73			`GET_FLOAT_WORD(hu,u);`
74			`k = (hu>>23)-127;`
75			`/* correction term */`
76			`c = (k>0)? (float)1.0-(u-x):x-(u-(float)1.0);`
77			`c /= u;`
78			`} else {`
79			`u = x;`
80			`GET_FLOAT_WORD(hu,u);`
81			`k = (hu>>23)-127;`
82			`c = 0;`
83			`}`
84			`hu &= 0x007fffff;`
85			`if(hu<0x3504f7) {`
86			`SET_FLOAT_WORD(u,hu\|0x3f800000);/* normalize u */`
87			`} else {`
88			`k += 1;`
89			`SET_FLOAT_WORD(u,hu\|0x3f000000); /* normalize u/2 */`
90			`hu = (0x00800000-hu)>>2;`
91			`}`
92			`f = u-(float)1.0;`
93			`}`
94			`hfsq=(float)0.5ff;`
95			`if(hu==0) { /* \|f\| < 2*-20 /`
96			`if(f==zero) if(k==0) return zero;`
97			`else {c += kln2_lo; return kln2_hi+c;}`
98			`R = hfsq((float)1.0-(float)0.66666666666666666f);`
99			`if(k==0) return f-R; else`
100			`return kln2_hi-((R-(kln2_lo+c))-f);`
101			`}`
102			`s = f/((float)2.0+f);`
103			`z = s*s;`
104			`R = z(Lp1+z(Lp2+z(Lp3+z(Lp4+z(Lp5+z(Lp6+z*Lp7))))));`
105			`if(k==0) return f-(hfsq-s*(hfsq+R)); else`
106			`return kln2_hi-((hfsq-(s(hfsq+R)+(k*ln2_lo+c)))-f);`
107			`}`
108
109			`#ifdef _DOUBLE_IS_32BITS`
110
111			`#ifdef __STDC__`
112			`double log1p(double x)`
113			`#else`
114			`double log1p(x)`
115			`double x;`
116			`#endif`
117			`{`
118			`return (double) log1pf((float) x);`
119			`}`
120
121			`#endif /* defined(_DOUBLE_IS_32BITS) */`

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[/] [or1k/] [trunk/] [newlib/] [newlib/] [libm/] [math/] [sf_log1p.c] - Blame information for rev 1774