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/* @(#)s_floor.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 |
<<floor>>, <<floorf>>, <<ceil>>, <<ceilf>>---floor and ceiling |
INDEX |
floor |
INDEX |
floorf |
INDEX |
ceil |
INDEX |
ceilf |
|
ANSI_SYNOPSIS |
#include <math.h> |
double floor(double <[x]>); |
float floorf(float <[x]>); |
double ceil(double <[x]>); |
float ceilf(float <[x]>); |
|
TRAD_SYNOPSIS |
#include <math.h> |
double floor(<[x]>) |
double <[x]>; |
float floorf(<[x]>) |
float <[x]>; |
double ceil(<[x]>) |
double <[x]>; |
float ceilf(<[x]>) |
float <[x]>; |
|
DESCRIPTION |
<<floor>> and <<floorf>> find |
@tex |
$\lfloor x \rfloor$, |
@end tex |
the nearest integer less than or equal to <[x]>. |
<<ceil>> and <<ceilf>> find |
@tex |
$\lceil x\rceil$, |
@end tex |
the nearest integer greater than or equal to <[x]>. |
|
RETURNS |
<<floor>> and <<ceil>> return the integer result as a double. |
<<floorf>> and <<ceilf>> return the integer result as a float. |
|
PORTABILITY |
<<floor>> and <<ceil>> are ANSI. |
<<floorf>> and <<ceilf>> are extensions. |
|
|
*/ |
|
/* |
* floor(x) |
* Return x rounded toward -inf to integral value |
* Method: |
* Bit twiddling. |
* Exception: |
* Inexact flag raised if x not equal to floor(x). |
*/ |
|
#include "fdlibm.h" |
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#ifndef _DOUBLE_IS_32BITS |
|
#ifdef __STDC__ |
static const double huge = 1.0e300; |
#else |
static double huge = 1.0e300; |
#endif |
|
#ifdef __STDC__ |
double floor(double x) |
#else |
double floor(x) |
double x; |
#endif |
{ |
__int32_t i0,i1,j0; |
__uint32_t i,j; |
EXTRACT_WORDS(i0,i1,x); |
j0 = ((i0>>20)&0x7ff)-0x3ff; |
if(j0<20) { |
if(j0<0) { /* raise inexact if x != 0 */ |
if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ |
if(i0>=0) {i0=i1=0;} |
else if(((i0&0x7fffffff)|i1)!=0) |
{ i0=0xbff00000;i1=0;} |
} |
} else { |
i = (0x000fffff)>>j0; |
if(((i0&i)|i1)==0) return x; /* x is integral */ |
if(huge+x>0.0) { /* raise inexact flag */ |
if(i0<0) i0 += (0x00100000)>>j0; |
i0 &= (~i); i1=0; |
} |
} |
} else if (j0>51) { |
if(j0==0x400) return x+x; /* inf or NaN */ |
else return x; /* x is integral */ |
} else { |
i = ((__uint32_t)(0xffffffff))>>(j0-20); |
if((i1&i)==0) return x; /* x is integral */ |
if(huge+x>0.0) { /* raise inexact flag */ |
if(i0<0) { |
if(j0==20) i0+=1; |
else { |
j = i1+(1<<(52-j0)); |
if(j<i1) i0 +=1 ; /* got a carry */ |
i1=j; |
} |
} |
i1 &= (~i); |
} |
} |
INSERT_WORDS(x,i0,i1); |
return x; |
} |
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#endif /* _DOUBLE_IS_32BITS */ |