/*
 * Revision Control Information
 *
 * $Source: /vol/opua/opua2/sis/sis-1.2/common/src/stamina/mimi/RCS/stack.c,v $
 * $Author: sis $
 * $Revision: 1.3 $
 * $Date: 1994/07/15 22:58:50 $
 *
 */
/* SCCSID %W% */
#include "util.h"
#include "struct.h"
#include "global.h"
#include "stack.h"
#include "merge.h"

STACK *xstack;
static unsigned int _size;
static int *_local[STACKLIMIT];
static int **top_of_stack;
static int **stack_ptr;

/* Emulation of the stack operation */
/* This routine guarantees compact use of memory */
/* But is must pay for it in terms of time */

alloc_stack(size)
{
	if ((xstack = ALLOC(STACK,size)) == NIL(STACK))
		panic("ALLOC in init_stack");
}

free_stack_head()
{
	if (FREE(xstack))
		panic("lint");
}

init_stack(id)
{
	_size = 0;
	top_of_stack = _local;
	stack_ptr = _local;
	xstack[id].status = CONDITIONAL_COMPATIBLE;
}

open_stack(id)
{
	stack_ptr = xstack[id].ptr;
	top_of_stack = (int **)*stack_ptr;
	stack_ptr = (int **)*(stack_ptr + 1);
}

close_stack(id,status)
{
	xstack[id].ptr = NIL(int *);
	xstack[id].status = status;
}

free_stack(id,status)
{
	if (FREE(xstack[id].ptr))
		panic("lint");
	xstack[id].ptr = NIL(int *);
	xstack[id].status = status;
}

pack_stack(id)
{
	int **real_alloc;

	if ((real_alloc = ALLOC(int *,_size+2)) == NIL(int *))
		panic("ALLOC in stack");
	xstack[id].ptr = real_alloc;
	xstack[id].status = CONDITIONAL_COMPATIBLE;
	*real_alloc = (int *)(real_alloc + 2);
	real_alloc++;
	*real_alloc = (int *)(real_alloc + _size + 1);
	MEMCPY(++real_alloc,_local,sizeof(char *)*_size);	
}

push(state2,state1)
{
#ifdef DEBUG
(void) printf("Push %s %s \n",states[state1]->state_name,states[state2]->state_name);
#endif
	if (state2 >  state1)
	_push(&xstack[(num_st-state1-2)*(num_st-state1-1)/2-state2+num_st-1]);
	else
	_push(&xstack[(num_st-state2-2)*(num_st-state2-1)/2-state1+num_st-1]);
}

static
_push(operand)
int *operand;
{
	*stack_ptr++ = operand;	
	if (_size++ > STACKLIMIT)
		panic("Stack Overflow");
}

/*
STACK *
_pop(arg2)
STACK **arg2;
{
	if ((*arg2 = pop()) == NIL(STACK))
		return NIL(STACK);
	else
		return(pop());
}
*/

STACK *
pop()
{
	if (stack_ptr == top_of_stack)
		return EMPTY;
	else 
		return (STACK *)*--stack_ptr;
}

#ifdef DEBUG
dump_stack(id)
{
	int **stack;
	register i;

	
	stack = xstack[id].ptr;
	(void) printf("STACK SIZE %d\n",_size);
	for (i=0; i<_size+2; i++) {
		(void) printf("ADDRESS: %x VALUE %x\n",stack,*stack);
		stack++;
	}
}
#endif