diff options
author | Christopher Faylor <me@cgf.cx> | 2000-02-17 22:39:52 +0300 |
---|---|---|
committer | Christopher Faylor <me@cgf.cx> | 2000-02-17 22:39:52 +0300 |
commit | 8a0efa53e44919bcf5ccb1d3353618a82afdf8bc (patch) | |
tree | 68c3dbf3f2c6fd5d49777def9914d77b5cd4589d /newlib/libm/common/s_nextafter.c | |
parent | 1fd5e000ace55b323124c7e556a7a864b972a5c4 (diff) |
import newlib-2000-02-17 snapshot
Diffstat (limited to 'newlib/libm/common/s_nextafter.c')
-rw-r--r-- | newlib/libm/common/s_nextafter.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/newlib/libm/common/s_nextafter.c b/newlib/libm/common/s_nextafter.c new file mode 100644 index 000000000..82eb8e3ed --- /dev/null +++ b/newlib/libm/common/s_nextafter.c @@ -0,0 +1,121 @@ + +/* @(#)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 */ |