/*****************************************************************************

	DoCJR()

	This function contains the code that's common to the C, J and R
commands.  It is called by ExeC, ExeJ and ExeR only.

*****************************************************************************/

#include "zport.h"		/* define portability identifiers */
#include "tecoc.h"		/* define general identifiers */
#include "defext.h"		/* define external global variables */
#include "deferr.h"		/* define identifiers for error messages */

DEFAULT DoCJR(HowFar)		/* do C, J or R stuff */
LONG HowFar;			/* positive or negative displacement */
{
	LONG	InRange;
	BOOLEAN	ColonMod;

#if DEBUGGING
	static char *DbgFNm = "DoCJR";
	sprintf(DbgSBf,"HowFar = %ld", HowFar);
	DbgFEn(2,DbgFNm,DbgSBf);
#endif

	ColonMod = (CmdMod & COLON);		/* is it :C, :J, or :R? */
	CmdMod &= ~COLON;			/* clear : flag */

	InRange = -1;				/* -1 means SUCCESS in TECO */
	if (HowFar > 0) {
		if ((GapEnd+HowFar) > EBfEnd) {
			InRange = 0;		/* 0 means FAILURE in TECO */
		} else {
			MEMMOVE(GapBeg, GapEnd+1, HowFar);
			GapBeg += HowFar;
			GapEnd += HowFar;
		}
	} else {
		if ((GapBeg+HowFar) < EBfBeg) {
			InRange = 0;		/* 0 means FAILURE in TECO */
		} else {
			GapBeg += HowFar;
			GapEnd += HowFar;
			MEMMOVE(GapEnd+1, GapBeg, -(HowFar));
		}
	}

	if (ColonMod) {				/* if colon modifier */
		DBGFEX(2,DbgFNm,"PushEx");
		return PushEx(InRange, OPERAND);
	} else {
		if (InRange == 0) {		/* if out-of-bounds */
			ErrChr(ERR_POP, *CBfPtr);
			DBGFEX(2,DbgFNm,"FAILURE");
			return FAILURE;
		}
	}

	CmdMod = '\0';				/* clear modifiers flags */
	EStTop = EStBot;			/* clear expression stack */

	DBGFEX(2,DbgFNm,"SUCCESS");

	return SUCCESS;
}