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/* origin: FreeBSD /usr/src/lib/msun/src/s_modf.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.
* ====================================================
*/
/*
* modf(double x, double *iptr)
* return fraction part of x, and return x's integral part in *iptr.
* Method:
* Bit twiddling.
*
* Exception:
* No exception.
*/
#include "libm.h"
static const double one = 1.0;
double modf(double x, double *iptr)
{
int32_t i0,i1,j0;
uint32_t i;
EXTRACT_WORDS(i0, i1, x);
j0 = ((i0>>20) & 0x7ff) - 0x3ff; /* exponent of x */
if (j0 < 20) { /* integer part in high x */
if (j0 < 0) { /* |x| < 1 */
INSERT_WORDS(*iptr, i0 & 0x80000000, 0); /* *iptr = +-0 */
return x;
}
i = 0x000fffff >> j0;
if (((i0&i)|i1) == 0) { /* x is integral */
uint32_t high;
*iptr = x;
GET_HIGH_WORD(high, x);
INSERT_WORDS(x, high & 0x80000000, 0); /* return +-0 */
return x;
}
INSERT_WORDS(*iptr, i0&~i, 0);
return x - *iptr;
} else if (j0 > 51) { /* no fraction part */
uint32_t high;
if (j0 == 0x400) { /* inf/NaN */
*iptr = x;
return 0.0 / x;
}
*iptr = x*one;
GET_HIGH_WORD(high, x);
INSERT_WORDS(x, high & 0x80000000, 0); /* return +-0 */
return x;
} else { /* fraction part in low x */
i = (uint32_t)0xffffffff >> (j0 - 20);
if ((i1&i) == 0) { /* x is integral */
uint32_t high;
*iptr = x;
GET_HIGH_WORD(high, x);
INSERT_WORDS(x, high & 0x80000000, 0); /* return +-0 */
return x;
}
INSERT_WORDS(*iptr, i0, i1&~i);
return x - *iptr;
}
}
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