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/*
* ====================================================
* 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.
* ====================================================
*/
#include "fdlibm.h"
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
double trunc(double x)
#else
double trunc(x)
double x;
#endif
{
int signbit;
/* Most significant word, least significant word. */
int msw;
unsigned int lsw;
int exponent_less_1023;
EXTRACT_WORDS(msw, lsw, x);
/* Extract sign bit. */
signbit = msw & 0x80000000;
/* Extract exponent field. */
exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
if (exponent_less_1023 < 20)
{
/* All significant digits are in msw. */
if (exponent_less_1023 < 0)
{
/* -1 < x < 1, so result is +0 or -0. */
INSERT_WORDS(x, signbit, 0);
}
else
{
/* All relevant fraction bits are in msw, so lsw of the result is 0. */
INSERT_WORDS(x, signbit | (msw & ~(0x000fffff >> exponent_less_1023)), 0);
}
}
else if (exponent_less_1023 > 51)
{
if (exponent_less_1023 == 1024)
{
/* x is infinite, or not a number, so trigger an exception. */
return x + x;
}
/* All bits in the fraction fields of the msw and lsw are needed in the result. */
}
else
{
/* All fraction bits in msw are relevant. Truncate irrelevant
bits from lsw. */
INSERT_WORDS(x, msw, lsw & ~(0xffffffffu >> (exponent_less_1023 - 20)));
}
return x;
}
#endif /* _DOUBLE_IS_32BITS */
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