68 lines
1.3 KiB
C
68 lines
1.3 KiB
C
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/* void _CosDec80Bit(pDst,pSrc)
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*
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* ARGUMENT
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* DEC *pDst, *pSrc;
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*
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* DESCRIPTION
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* Sets pDst = the cosine of pSrc radians.
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*
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* SIDE EFFECTS
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* None.
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*
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* RETURNS
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* None. No errors are possible.
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*
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* AUTHOR
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* Jared Levy October 16, 1987
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* Copyright (C) 1987-1990 Greenleaf Software Inc. All rights reserved.
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*
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* MODIFICATIONS
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*
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*/
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#include <stdio.h>
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#include "gm.h"
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#include "gmsystem.h"
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void _CosDec80Bit(pDst,pSrc)
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DEC *pDst, *pSrc;
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{
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DEC dnsrc, *nsrc, dtemp, *temp;
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int isn=0;
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nsrc = &dnsrc;
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_MacDCopy(nsrc, pSrc);
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/* scale nsrc to range 0 to pi */
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if (_MacIsDecN(nsrc))
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_MacDChgs(nsrc);
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if (CompareDecimal(nsrc, &decPi) == 1) {
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temp = &dtemp;
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(void) _DivRndDec80Bit(temp, nsrc, &dec2Pi, 0);
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(void) _MulDec80Bit(temp, temp, &dec2Pi);
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(void) _SubDec80Bit(nsrc, nsrc, temp);
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if (_MacIsDecN(nsrc))
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_MacDChgs(nsrc);
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}
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/* scale nsrc to range 0 to pi / 2 */
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if (CompareDecimal(nsrc, &decPiOver2) == 1) {
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isn = 1;
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(void) _SubDec80Bit(nsrc, &decPi, nsrc);
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}
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/* calculate appropriate Taylor series */
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if (CompareDecimal(nsrc, &decPiOver4) == 1) {
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(void) _SubDec80Bit(nsrc, &decPiOver2, nsrc);
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_SinDecSmall(pDst, nsrc); /* sine series */
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}
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else
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_CosDecSmall(pDst, nsrc); /* cosine series */
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/* adjust for negative values */
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if (isn)
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_MacDChgs(pDst);
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}
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