OpenLibm/ld80/s_ceill.c

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/* @(#)s_ceil.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.
* ====================================================
*/
/*
* ceill(x)
* Return x rounded toward -inf to integral value
* Method:
* Bit twiddling.
* Exception:
* Inexact flag raised if x not equal to ceil(x).
*/
#include <openlibm_math.h>
#include "math_private.h"
static const long double huge = 1.0e4930L;
long double
ceill(long double x)
{
int32_t i1,jj0;
u_int32_t i,j,se,i0,sx;
GET_LDOUBLE_WORDS(se,i0,i1,x);
sx = (se>>15)&1;
jj0 = (se&0x7fff)-0x3fff;
if(jj0<31) {
if(jj0<0) { /* raise inexact if x != 0 */
if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
if(sx) {se=0x8000;i0=0;i1=0;}
else if((i0|i1)!=0) { se=0x3fff;i0=0;i1=0;}
}
} else {
i = (0x7fffffff)>>jj0;
if(((i0&i)|i1)==0) return x; /* x is integral */
if(huge+x>0.0) { /* raise inexact flag */
if(sx==0) {
if (jj0>0 && (i0+(0x80000000>>jj0))>i0)
i0+=0x80000000>>jj0;
else
{
i = 0x7fffffff;
++se;
}
}
i0 &= (~i); i1=0;
}
}
} else if (jj0>62) {
if(jj0==0x4000) return x+x; /* inf or NaN */
else return x; /* x is integral */
} else {
i = ((u_int32_t)(0xffffffff))>>(jj0-31);
if((i1&i)==0) return x; /* x is integral */
if(huge+x>0.0) { /* raise inexact flag */
if(sx==0) {
if(jj0==31) i0+=1;
else {
j = i1 + (1<<(63-jj0));
if(j<i1) i0+=1; /* got a carry */
i1 = j;
}
}
i1 &= (~i);
}
}
SET_LDOUBLE_WORDS(x,se,i0,i1);
return x;
}