/* DEC	*PowerInteger(pDst,pSrc,i)
 *
 * ARGUMENT
 *	DEC	*pDst,*pSrc;
 *	int	i;
 *
 * DESCRIPTION
 *	Raises pSrc to the power 'i'. If i<0, raises pSrc to the |i|, then
 *  takes the reciprocal(ie, if	i<0, then x**i = 1/x**|i|). If x=0, then
 *  if i=<0, then error	(GM_NAN), else pDst is set to 1. If x<0, then if the
 *  power is odd, the result will be negative, otherwise positive. The
 *  absolute value cannot exceed 2**63 -1. Note	we call	dpoxi()	because
 *  other high-level functions need returns of 2**79 -1, which is what
 *  this routine gets back and then sqeezes it back to 64-bits.
 *
 * SIDE	EFFECTS
 *	*pDst is indeterminate on overflow, underflow. It is undisturbed
 *  on GM_NULLPOINTER.
 *
 * RETURNS
 *	Ptr to pDst if no errors, otherwise GM_NULL.
 *
 * POSSIBLE ERROR CODES
 *
 *	GM_NULLPOINTER
 *	GM_OVERFLOW
 *	GM_UNDERFLOW
 *
 * AUTHOR
 *  Andy Anderson   08-05-87	1130
 *   Copyright (C) 1987-1990 Greenleaf Software	Inc.  All rights reserved.
 *
 * MODIFICATIONS
 *
 */

#include <stdio.h>
#include "gm.h"
#include "gmsystem.h"

DEC	*PowerInteger(pDst,pSrc,i)
DEC	*pDst,*pSrc;
int	i;
{
	int	wRetVal;

	_MacStart(GM_DPOWI);
	_MacInVarD(pSrc);
	_MacOutVarD(pDst);

	if (_MacIsDecZ(pSrc) &&	(i<=0))	 {
		_MacErr(GM_PWR0);
		_MacRet(GM_NULL);
	}

	if (_MacIsDecZ(pSrc))  {
		_MacDZero(pDst);
		_MacRet(pDst);
	}

	wRetVal=_IntPwrDec80Bit(pDst,pSrc,i);

	/* then	see if success */
	if(wRetVal == GM_OVERFLOW) {
		_MacErr(wRetVal);
		_MacRet(GM_NULL);
	}

	/* then	try to reduce to 64-bit	*/
	wRetVal	= _Sq5UnsTo4Uns(pDst);	/* places or it's an error */

	if(wRetVal != GM_SUCCESS) {
		_MacErr(GM_OVERFLOW);
		_MacRet(GM_NULL);
	}

	if (_MacIsDecZ(pDst))  {
		_MacErr(GM_UNDERFLOW);
	}

	_MacRet(pDst);
}