/************************************************************************
*									*
*	The SB-Prolog System						*
*	Copyright SUNY at Stony Brook, 1986				*
*									*
************************************************************************/

/*-----------------------------------------------------------------
SB-Prolog is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY.  No author or distributor
accepts responsibility to anyone for the consequences of using it
or for whether it serves any particular purpose or works at all,
unless he says so in writing.  Refer to the SB-Prolog General Public
License for full details.

Everyone is granted permission to copy, modify and redistribute
SB-Prolog, but only under the conditions described in the
SB-Prolog General Public License.   A copy of this license is
supposed to have been given to you along with SB-Prolog so you
can know your rights and responsibilities.  It should be in a
file named COPYING.  Among other things, the copyright notice
and this notice must be preserved on all copies. 
------------------------------------------------------------------ */


/* sub_inst.c */

#include <signal.h>
#include "sim.h"
#include "aux.h"

struct sigvec vec;

/* set interrupt code in reg 2 and return ep of interrupt handler */
byte *set_intercode(intcode)
int intcode;
{
    if (!is_PRED(interrupt_psc))
        quit("Interrupt handler not defined\n");

    gregc(2) = makeint(intcode);
    return(get_ep(interrupt_psc));
}

intercept_proc()
{
    if (interrupt_code == 0) {
	interrupt_code = 1;
    }
    else exit(2);
}

arm_intercept()
{
    /* set up interrupt routine */
    vec.sv_handler = intercept_proc;
    vec.sv_mask = 0;
    vec.sv_onstack = 0;
    sigvec(2, &vec, 0);
}
/****************************************************************************/


callv_sub()   /* arg from register 1 */
{
    word term;
    register    pw top;
    short int   i;
    struct psc_rec *psc_ptr;
    char    s1[256];

    term = gregc(1);
    cvlab: switch ((int)(term & TAGMASK)) {
	case FREE: 
	    nderef (term, cvlab);
	case NUM: 
	    printf("illegal call\n");
	    Fail0;
	    return;
	case LIST: 
	    psc_ptr = list_psc;
	    term -= 4;
	    goto cstst;
	case CS: 
	    psc_ptr = get_str_psc(term);
	  cstst:
	    if (interrupt_code > 0)
	    {	interrupt_code = 0;
		pcreg = set_intercode(1);
		return;
	    };
	    /* call code */
	    if (is_PRED(psc_ptr) || is_DYNA(psc_ptr))
		pcreg = get_ep(psc_ptr);
	    else
	    {	pcreg = set_intercode(0);
		return;
	    }
	    untag(term);
	    for (i = 1; i <= get_arity(psc_ptr); ++i)
		gregc(i) = follow((pw) term + i);
	}
	if (hitrace == 1)
	{   printf("callv: ");
	    writepname(stdout, get_name(psc_ptr), get_length(psc_ptr));
	    printf("        (");
	    for (i = 1; i <= get_arity(psc_ptr); i++)
	    {	printf(" ");
		printterm(gregc(i), 1);
	    }
	    printf(")\n");
	}
}

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


/* builds the current call onto the heap and points reg 1 to it, 
   and puts the interrupt number in reg 2 */

build_call(psc)
struct psc_rec *psc;
{
    register word callstr, arg;
    register pw top;
    register int i;

    callstr = (word)hreg;	/* save addr of new structure rec */
    new_heap_node((word)psc); /* set str psc ptr */
    for ( i=1; i<=get_arity(psc); i++) {
	arg = gregc(i);
	bldc: if ((arg & 3) == 0) {
	    nderef(arg, bldc);
	    follow(arg) = (word)hreg;
	    pushtrail(arg);
	    new_heap_free;
	    }
	else new_heap_node(arg);
	}
    gregc(1) = callstr | CS_TAG; /* ptr to new structure on heap */
}