/*
file TAPE.H
     A tape is a linked list of cells.  Each cell contains a symbol.
*/

#ifndef TAPE_H
#include "limits.h"

struct cell
      {
/*      SYMBOL *symbol;    */      /* the symbol contained in this cell */
      SYMBOL Csymbol;                /* the symbol contained in this cell */
      struct cell *lptr;     /* pointer to a cell on the left */
      struct cell *rptr;     /* pointer to a cell on the right */
      };

struct tape
      {
      struct cell *root;   /* pointer to the tape-- the linked list root */
      struct cell *head;            /* the tape head location */
      struct cell *leftend;   /* left end of the tape */
      int tape_len;          /* length of the tape */
      };
#endif

/* prototypes..... */

struct cell *new_cell(int *status);
/*
Create a new cell, initialize it to a blank.
*/

void delete_tape(struct tape *tptr);
/*
Delete all the cells on a tape.
*/

struct cell *init_tape(struct tape *tptr);
/*
Create a new tape.
*/

struct cell *make_rcell(struct tape *tptr);
/*
If head goes off the right end, create a new blank cell.
*/

struct cell *make_lcell(struct tape *tptr);
/*
If head goes off the left end, create a new blank cell.
*/

struct cell *move_head(struct tape *tptr, char ch);
/*
Move the head left or right, depending on whether 'ch' is either 'L' or 'R'
*/

void show_tape(struct tape *tptr, int *status);
/*
Print the tape.  Indicate the tape head location with a '^', and show the
machine state.
*/

void get_new_tape(struct tape *tptr, int *status);
/*
Get a new tape from standard input.  Delete the old tape if it exists.
*/

#define TAPE_H