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80 lines
1.8 KiB
80 lines
1.8 KiB
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/* @(#)s_modf.c 1.3 95/01/18 */ |
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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 SunSoft, 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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* ieee_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 ieee_modf(double x, double *iptr) |
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#else |
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double ieee_modf(x, iptr) |
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double x,*iptr; |
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#endif |
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{ |
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int i0,i1,j0; |
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unsigned 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 = ((unsigned)(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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