62 lines
880 B
C
62 lines
880 B
C
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/* DEC *Factorial(pDst, n)
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*
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* ARGUMENT
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* DEC *pDst;
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* unsigned n;
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*
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* DESCRIPTION
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* Sets pDst = n!
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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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* pDst if successful, GM_NULL otherwise
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*
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* POSSIBLE ERRORS
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* GM_NOMEMORY
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* GM_OVERFLOW (if n > 20)
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*
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* AUTHOR
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* Jared Levy
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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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*/
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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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DEC *Factorial(pDst, n)
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DEC *pDst;
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unsigned n;
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{
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DEC dmult, *mult = &dmult;
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unsigned i;
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_MacStart(GM_DFACT);
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_MacOutVarD(pDst);
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/* check for overflow */
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if (n > 20) {
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_MacErr(GM_OVERFLOW);
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_MacRet(GM_NULL);
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}
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/* do calculations */
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_MacDCopy(pDst, &decOne);
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_MacDCopy(mult, &decOne);
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for (i=2; i<=n; i++) {
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mult->dc.sl[0] = i;
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_MulDec80Bit(pDst, pDst, mult);
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}
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/* pDst fits into 64 bits */
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_MacRet(pDst);
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}
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