49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
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/* _Dnorm function -- IEEE 754 version */
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#include "wctype.h"
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#include "xmath.h"
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_STD_BEGIN
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_CRTIMP2 short _Dnorm(unsigned short *ps)
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{ /* normalize double fraction */
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short xchar;
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unsigned short sign = ps[_D0] & _DSIGN;
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xchar = 1;
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if ((ps[_D0] &= _DFRAC) != 0 || ps[_D1]
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|| ps[_D2] || ps[_D3])
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{ /* nonzero, scale */
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for (; ps[_D0] == 0; xchar -= 16)
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{ /* shift left by 16 */
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ps[_D0] = ps[_D1], ps[_D1] = ps[_D2];
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ps[_D2] = ps[_D3], ps[_D3] = 0;
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}
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for (; ps[_D0] < 1<<_DOFF; --xchar)
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{ /* shift left by 1 */
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ps[_D0] = ps[_D0] << 1 | ps[_D1] >> 15;
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ps[_D1] = ps[_D1] << 1 | ps[_D2] >> 15;
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ps[_D2] = ps[_D2] << 1 | ps[_D3] >> 15;
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ps[_D3] <<= 1;
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}
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for (; 1<<(_DOFF+1) <= ps[_D0]; ++xchar)
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{ /* shift right by 1 */
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ps[_D3] = ps[_D3] >> 1 | ps[_D2] << 15;
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ps[_D2] = ps[_D2] >> 1 | ps[_D1] << 15;
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ps[_D1] = ps[_D1] >> 1 | ps[_D0] << 15;
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ps[_D0] >>= 1;
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}
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ps[_D0] &= _DFRAC;
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}
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ps[_D0] |= sign;
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return (xchar);
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}
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_STD_END
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/*
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* Copyright (c) 1994 by P.J. Plauger. ALL RIGHTS RESERVED.
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* Consult your license regarding permissions and restrictions.
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*/
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/*
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941029 pjp: added _STD machinery
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*/
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