mirror of https://github.com/PrimeDecomp/prime.git
80 lines
1.9 KiB
C
80 lines
1.9 KiB
C
/* @(#)s_modf.c 1.2 95/01/04 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* modf(double x, double *iptr)
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* return fraction part of x, and return x's integral part in *iptr.
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* Method:
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* Bit twiddling.
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*
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* Exception:
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* No exception.
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*/
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#include "fdlibm.h"
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#ifdef __STDC__
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static const double one = 1.0;
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#else
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static double one = 1.0;
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#endif
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#ifdef __STDC__
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double modf(double x, double* iptr)
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#else
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double modf(x, iptr)
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double x, *iptr;
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#endif
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{
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_INT32 i0, i1, j0;
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_UINT32 i;
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i0 = __HI(x); /* high x */
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i1 = __LO(x); /* low x */
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j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; /* exponent of x */
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if (j0 < 20) { /* integer part in high x */
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if (j0 < 0) { /* |x|<1 */
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__HIp(iptr) = i0 & 0x80000000;
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__LOp(iptr) = 0; /* *iptr = +-0 */
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return x;
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} else {
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i = (0x000fffff) >> j0;
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if (((i0 & i) | i1) == 0) { /* x is integral */
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*iptr = x;
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__HI(x) &= 0x80000000;
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__LO(x) = 0; /* return +-0 */
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return x;
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} else {
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__HIp(iptr) = i0 & (~i);
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__LOp(iptr) = 0;
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return x - *iptr;
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}
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}
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} else if (j0 > 51) { /* no fraction part */
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*iptr = x * one;
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__HI(x) &= 0x80000000;
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__LO(x) = 0; /* return +-0 */
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return x;
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} else { /* fraction part in low x */
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i = ((_UINT32)(0xffffffff)) >> (j0 - 20);
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if ((i1 & i) == 0) { /* x is integral */
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*iptr = x;
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__HI(x) &= 0x80000000;
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__LO(x) = 0; /* return +-0 */
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return x;
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} else {
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__HIp(iptr) = i0;
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__LOp(iptr) = i1 & (~i);
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return x - *iptr;
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}
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}
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}
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