/* Z3func02 - Zcpr3 access functions for C */

#include <stdio.h>
#include "z3env.h"

#ifndef BDSC
struct env *envadr;
#endif

/* Shell manipulation */

/* Push command onto shell stack.  Returns TRUE if successful. */

int shpush(cl)
	char *cl;
{
	char *p;
	int i,j,size;
#ifdef BDSC
	struct env *zenv(), *envadr;

	envadr = zenv();
#endif
	p = envadr->shstk;
	size = envadr->shsize;	/* used a lot so remove a bit of indirection */
	if(p) {
		if(strlen(cl) > size)
			return(FALSE);	/* gag if entry is too large */
		for(i=j=0;i < envadr->shstks-1;++i)
			j+=size;	/* faster than a multiply */
		if(*(p+j) != '\0') 	/* test that stack is not full */
			return(FALSE);	/* gag if it is */
		movmem(p,p+size,j);	/* push all entries down 1 */
		setmem(p,size,0);	/* clear out entire entry */
		strncpy(p,cl,size);	/* copy onto stack */
		return(TRUE);
	} else
		return(FALSE);
}


/* Pop shell stack.  Returns TRUE if successful. */

int shpop()
{
	char *p, *q;
	int i,j,size;
#ifdef BDSC
	struct env *zenv(), *envadr;

	envadr = zenv();
#endif
	p = envadr->shstk;
	size = envadr->shsize;
	if(p && *p) {
		if(envadr->shstks > 1) {
			for(i=j=0;i < envadr->shstks-1;++i)
				j+=size;	/* faster than a multiply */
			if(j)
				movmem(p+size,p,j);	/* all remaining entries down 1 */
			p+=j;	/* point to empty entry at end of stack */
		}
		setmem(p,size,0);	/* clear out entire empty entry */
		return(TRUE);
	} else
		return(FALSE);
}


/* Test for shell stack empty */

int shempty()
{
#ifdef BDSC
	struct env *zenv();

	return(*(zenv().shstk) ? FALSE : TRUE);
#else
	return(*(envadr->shstk) ? FALSE : TRUE);
#endif
}


/* Test for shell stack full */

int shfull()
{
	int i,j;
#ifdef BDSC
	struct env *zenv(), *envadr;

	envadr = zenv();
#endif
	for(i=j=0;i < envadr->shstks-1;++i)
		j+=envadr->shsize;	/* faster than a multiply */
	return(*(envadr->shstk+j) != '\0');
}