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/* @(#)s_nextafter.c 5.1 93/09/24 */
/*
 * ====================================================
 * 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.
 * ====================================================
 */
 
/*
FUNCTION
       <<nextafter>>, <<nextafterf>>---get next number
 
INDEX
        nextafter
INDEX
        nextafterf
 
ANSI_SYNOPSIS
       #include <math.h>
       double nextafter(double <[val]>, double <[dir]>);
       float nextafterf(float <[val]>, float <[dir]>);
 
TRAD_SYNOPSIS
       #include <math.h>
 
       double nextafter(<[val]>, <[dir]>)
              double <[val]>;
              double <[exp]>;
 
       float nextafter(<[val]>, <[dir]>)
              float <[val]>;
              float <[dir]>;
 
 
DESCRIPTION
<<nextafter>> returns the double) precision floating point number
closest to <[val]> in the direction toward <[dir]>.  <<nextafterf>>
performs the same operation in single precision.  For example,
<<nextafter(0.0,1.0)>> returns the smallest positive number which is
representable in double precision.
 
RETURNS
Returns the next closest number to <[val]> in the direction toward
<[dir]>.
 
PORTABILITY
        Neither <<nextafter>> nor <<nextafterf>> is required by ANSI C
        or by the System V Interface Definition (Issue 2).
*/
 
/* IEEE functions
 *      nextafter(x,y)
 *      return the next machine floating-point number of x in the
 *      direction toward y.
 *   Special cases:
 */
 
#include "fdlibm.h"
 
#ifndef _DOUBLE_IS_32BITS
 
#ifdef __STDC__
        double nextafter(double x, double y)
#else
        double nextafter(x,y)
        double x,y;
#endif
{
        __int32_t       hx,hy,ix,iy;
        __uint32_t lx,ly;
 
        EXTRACT_WORDS(hx,lx,x);
        EXTRACT_WORDS(hy,ly,y);
        ix = hx&0x7fffffff;             /* |x| */
        iy = hy&0x7fffffff;             /* |y| */
 
        if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */
           ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))     /* y is nan */
           return x+y;
        if(x==y) return x;              /* x=y, return x */
        if((ix|lx)==0) {                 /* x == 0 */
            INSERT_WORDS(x,hy&0x80000000,1);    /* return +-minsubnormal */
            y = x*x;
            if(y==x) return y; else return x;   /* raise underflow flag */
        }
        if(hx>=0) {                              /* x > 0 */
            if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
                if(lx==0) hx -= 1;
                lx -= 1;
            } else {                            /* x < y, x += ulp */
                lx += 1;
                if(lx==0) hx += 1;
            }
        } else {                                /* x < 0 */
            if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
                if(lx==0) hx -= 1;
                lx -= 1;
            } else {                            /* x > y, x += ulp */
                lx += 1;
                if(lx==0) hx += 1;
            }
        }
        hy = hx&0x7ff00000;
        if(hy>=0x7ff00000) return x+x;  /* overflow  */
        if(hy<0x00100000) {             /* underflow */
            y = x*x;
            if(y!=x) {          /* raise underflow flag */
                INSERT_WORDS(y,hx,lx);
                return y;
            }
        }
        INSERT_WORDS(x,hx,lx);
        return x;
}
 
#endif /* _DOUBLE_IS_32BITS */

Line No.	Rev	Author	Line
1	39	lampret
2			`/* @(#)s_nextafter.c 5.1 93/09/24 */`
3			`/*`
4			`* ====================================================`
5			`* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.`
6			`*`
7			`* Developed at SunPro, a Sun Microsystems, Inc. business.`
8			`* Permission to use, copy, modify, and distribute this`
9			`* software is freely granted, provided that this notice`
10			`* is preserved.`
11			`* ====================================================`
12			`*/`
13
14			`/*`
15			`FUNCTION`
16			`<<nextafter>>, <<nextafterf>>---get next number`
17
18			`INDEX`
19			`nextafter`
20			`INDEX`
21			`nextafterf`
22
23			`ANSI_SYNOPSIS`
24			`#include <math.h>`
25			`double nextafter(double <[val]>, double <[dir]>);`
26			`float nextafterf(float <[val]>, float <[dir]>);`
27
28			`TRAD_SYNOPSIS`
29			`#include <math.h>`
30
31			`double nextafter(<[val]>, <[dir]>)`
32			`double <[val]>;`
33			`double <[exp]>;`
34
35			`float nextafter(<[val]>, <[dir]>)`
36			`float <[val]>;`
37			`float <[dir]>;`
38
39
40			`DESCRIPTION`
41			`<<nextafter>> returns the double) precision floating point number`
42			`closest to <[val]> in the direction toward <[dir]>. <<nextafterf>>`
43			`performs the same operation in single precision. For example,`
44			`<<nextafter(0.0,1.0)>> returns the smallest positive number which is`
45			`representable in double precision.`
46
47			`RETURNS`
48			`Returns the next closest number to <[val]> in the direction toward`
49			`<[dir]>.`
50
51			`PORTABILITY`
52			`Neither <<nextafter>> nor <<nextafterf>> is required by ANSI C`
53			`or by the System V Interface Definition (Issue 2).`
54			`*/`
55
56			`/* IEEE functions`
57			`* nextafter(x,y)`
58			`* return the next machine floating-point number of x in the`
59			`* direction toward y.`
60			`* Special cases:`
61			`*/`
62
63			`#include "fdlibm.h"`
64
65			`#ifndef _DOUBLE_IS_32BITS`
66
67			`#ifdef __STDC__`
68			`double nextafter(double x, double y)`
69			`#else`
70			`double nextafter(x,y)`
71			`double x,y;`
72			`#endif`
73			`{`
74			`__int32_t hx,hy,ix,iy;`
75			`__uint32_t lx,ly;`
76
77			`EXTRACT_WORDS(hx,lx,x);`
78			`EXTRACT_WORDS(hy,ly,y);`
79			`ix = hx&0x7fffffff; /* \|x\| */`
80			`iy = hy&0x7fffffff; /* \|y\| */`
81
82			`if(((ix>=0x7ff00000)&&((ix-0x7ff00000)\|lx)!=0) \|\| /* x is nan */`
83			`((iy>=0x7ff00000)&&((iy-0x7ff00000)\|ly)!=0)) /* y is nan */`
84			`return x+y;`
85			`if(x==y) return x; /* x=y, return x */`
86			`if((ix\|lx)==0) { /* x == 0 */`
87			`INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */`
88			`y = x*x;`
89			`if(y==x) return y; else return x; /* raise underflow flag */`
90			`}`
91			`if(hx>=0) { /* x > 0 */`
92			`if(hx>hy\|\|((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */`
93			`if(lx==0) hx -= 1;`
94			`lx -= 1;`
95			`} else { /* x < y, x += ulp */`
96			`lx += 1;`
97			`if(lx==0) hx += 1;`
98			`}`
99			`} else { /* x < 0 */`
100			`if(hy>=0\|\|hx>hy\|\|((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */`
101			`if(lx==0) hx -= 1;`
102			`lx -= 1;`
103			`} else { /* x > y, x += ulp */`
104			`lx += 1;`
105			`if(lx==0) hx += 1;`
106			`}`
107			`}`
108			`hy = hx&0x7ff00000;`
109			`if(hy>=0x7ff00000) return x+x; /* overflow */`
110			`if(hy<0x00100000) { /* underflow */`
111			`y = x*x;`
112			`if(y!=x) { /* raise underflow flag */`
113			`INSERT_WORDS(y,hx,lx);`
114			`return y;`
115			`}`
116			`}`
117			`INSERT_WORDS(x,hx,lx);`
118			`return x;`
119			`}`
120
121			`#endif /* _DOUBLE_IS_32BITS */`

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[/] [or1k/] [trunk/] [newlib/] [newlib/] [libm/] [math/] [s_nextafter.c] - Blame information for rev 39