/** @file
 *  Sources of the "PROCEDURE CALL" group instructions
 */

/* $Id$ */

#include	"em_abs.h"
#include	"logging.h"
#include	"global.h"
#include	"log.h"
#include	"mem.h"
#include	"shadow.h"
#include	"memdirect.h"
#include	"segment.h"
#include	"trap.h"
#include	"warn.h"
#include	"text.h"
#include	"proctab.h"
#include	"fra.h"
#include	"rsb.h"
#include	"linfil.h"

extern int running;			/* from main.c */

/* Forward declarations */
PRIVATE void lfr(size), ret(size);
void call(long, int);

/** CAI -: Call procedure (procedure identifier on stack) */
void DoCAI(void)				/* proc identifier on top of stack */
{
	register long pi = spop(psize);

	LOG(("@P6 DoCAI(%lu)", pi));
	call(arg_p(pi), RSB_CAL);
}

/** CAL p: Call procedure (with identifier p) */
void DoCAL(register long pi)
{
	LOG(("@P6 DoCAL(%lu)", pi));
	call(arg_p(pi), RSB_CAL);
}

/** LFR s: Load function result */
void DoLFR(register size l)
{
	LOG(("@P6 DoLFR(%ld)", l));
	lfr(arg_s(l));
}

/** RET z: Return (function result consists of top z bytes) */
void DoRET(register size l)
{
	LOG(("@P6 DoRET(%ld)", l));
	ret(arg_z(l));
}

/************************************************************************
 *		Calling a new procedure.										*
 ************************************************************************/

void call(long new_PI, int rsbcode)
{
	/* legality of new_PI has already been checked */
	register size nloc = proctab[new_PI].pr_nloc;
	register ptr ep = proctab[new_PI].pr_ep;

	push_frame(SP);			/* remember AB */
	pushrsb(rsbcode);

	/* do the call */
	PI = new_PI;
	st_inc(nloc);
	newPC(ep);
	spoilFRA();
	LOG(("@p5 call: new_PI = %lu, nloc = %lu, ep = %lu",
				new_PI, nloc, ep));
}

/************************************************************************
 *		Loading a function result.										*
 ************************************************************************/

PRIVATE void lfr(size sz)
{
	if (sz > FRALimit) {
		wtrap(WILLLFR, EILLINS);
	}

	LOG(("@p5 lfr: size = %ld", sz));

#ifdef	LOGGING
	if (!FRA_def) {
		warning(WRFUNGAR);
	}
	if (sz != FRASize) {
		warning(FRASize < sz ? WRFUNSML : WRFUNLAR);
	}
#endif	/* LOGGING */

	pushFRA(sz);
	spoilFRA();
}

/************************************************************************
 *		Returning from a procedure.				*
 ************************************************************************/

PRIVATE void ret(size sz)
{
	if (sz > FRALimit) {
		wtrap(WILLRET, EILLINS);
	}

	LOG(("@p5 ret: size = %ld", sz));

	/* retrieve return value from stack */
	FRA_def = DEFINED;
	FRASize = sz;
	popFRA(FRASize);

	switch (poprsb(0)) {
	case RSB_STP:
		if (sz == wsize) {
			ES_def = DEFINED;
			ES = btol(FRA[sz-1]);
					/* one byte only */
		}
		running = 0;		/* stop the machine */
		return;
	case RSB_CAL:
		/* OK */
		break;
	case RSB_RTT:
	case RSB_NRT:
		warning(WRETTRAP);
		running = 0;		/* stop the machine */
		return;
	default:
		warning(WRETBAD);
		return;
	}
}