65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
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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 <math.h>
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#include <math_private.h>
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#include <libm-alias-double.h>
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#include <stdint.h>
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static const double one = 1.0;
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double
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__modf(double x, double *iptr)
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{
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int64_t i0;
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int32_t j0;
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EXTRACT_WORDS64(i0,x);
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j0 = ((i0>>52)&0x7ff)-0x3ff; /* exponent of x */
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if(j0<52) { /* integer part in x */
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if(j0<0) { /* |x|<1 */
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/* *iptr = +-0 */
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INSERT_WORDS64(*iptr,i0&UINT64_C(0x8000000000000000));
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return x;
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} else {
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uint64_t i = UINT64_C(0x000fffffffffffff)>>j0;
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if((i0&i)==0) { /* x is integral */
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*iptr = x;
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/* return +-0 */
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INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000));
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return x;
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} else {
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INSERT_WORDS64(*iptr,i0&(~i));
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return x - *iptr;
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}
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}
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} else { /* no fraction part */
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*iptr = x*one;
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/* We must handle NaNs separately. */
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if (j0 == 0x400 && (i0 & UINT64_C(0xfffffffffffff)))
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return x*one;
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INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000)); /* return +-0 */
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return x;
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}
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}
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#ifndef __modf
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libm_alias_double (__modf, modf)
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#endif
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