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/* origin: FreeBSD /usr/src/lib/msun/src/s_ceil.c */
/*
* ====================================================
* 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.
* ====================================================
*/
/*
* ceil(x)
* Return x rounded toward -inf to integral value
* Method:
* Bit twiddling.
* Exception:
* Inexact flag raised if x not equal to ceil(x).
*/
#include "libm.h"
static const double huge = 1.0e300;
double ceil(double x)
{
int32_t i0,i1,j0;
uint32_t i,j;
EXTRACT_WORDS(i0, i1, x);
// FIXME signed shift
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 = 0x80000000;
i1=0;
} else if ((i0|i1) != 0) {
i0=0x3ff00000;
i1=0;
}
}
} else {
i = (0x000fffff)>>j0;
if (((i0&i)|i1) == 0) /* x is integral */
return x;
/* raise inexact flag */
if (huge+x > 0.0) {
if (i0 > 0)
i0 += 0x00100000>>j0;
i0 &= ~i;
i1 = 0;
}
}
} else if (j0 > 51) {
if (j0 == 0x400) /* inf or NaN */
return x+x;
return x; /* x is integral */
} else {
i = (uint32_t)0xffffffff>>(j0-20);
if ((i1&i) == 0)
return x; /* x is integral */
/* raise inexact flag */
if (huge+x > 0.0) {
if (i0 > 0) {
if (j0 == 20)
i0 += 1;
else {
j = i1 + (1<<(52-j0));
if (j < i1) /* got a carry */
i0 += 1;
i1 = j;
}
}
i1 &= ~i;
}
}
INSERT_WORDS(x, i0, i1);
return x;
}
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