/*
 * button.h
 * 
 * Header file for list structure to hold enumerated playstation button values
 *
 * Author:	ScoTT Campbell
 * Date:	27/8/98
 *
 * It is up to the user of this package to ensure that they do not pass
 * NULL lists to functions.
*/


#ifndef __BUTTONLIST
#define __BUTTONLIST


#define NULL_BUTTON_LIST ((void*) 0)


enum buttons{CROSS, SQUARE, TRIANGLE, CIRCLE};
typedef enum buttons button_type;


typedef struct button_node* button_list_node_ptr;
typedef struct button_node{
		button_list_node_ptr	next, previous;
		button_type				buttonValue;
}button_list_node;


typedef struct button_head{
		button_list_node_ptr	front;
		button_list_node_ptr	back;
		button_list_node_ptr	current;
		unsigned long			length;
}button_list_head;

typedef button_list_head*	button_list;



button_list CreateButtonList();
/* Returns a new empty button list */

int BLClear(button_list);
/* Emptys a button list */ 
/* Returns 1 if successful; 0 otherwise */

int BLIsEmpty(button_list);
/* Returns 1 if the button list is empty; 0 otherwise */

int BLLength(button_list);
/* Returns the number of nodes in a button list */


/* Following functions return 0 if successful; 1 otherwise */ 

int BLAddFront(button_list, button_type);
/* Adds node to front of a button list and stores value of arg2 in it */

int BLAddBack(button_list, button_type);
/* Adds node to back of a button list and stores value of arg2 in it */

int BLAddBehindCurrent(button_list, button_type);
/* Adds node behind the current node and stores the value of arg2 in it */

int BLAddInFrontCurrent(button_list, button_type);
/* Adds node in front of the current node and stores the value of arg2 in it */



int BLGetFront(button_list, button_type*);
/* Removes node from front of a button list and puts the value held into *arg2 */

int BLGetBack(button_list, button_type*);
/* Removes node from back of a button list and puts the value held into *arg2 */

int BLGetCurrent(button_list, button_type*);
/* Removes node pointed to by the current pointer and puts the value held into *arg2 */


int BLReturnFront(button_list, button_type*);
/* Puts value held at front of list into *arg2 */

int BLReturnBack(button_list, button_type*);
/* Puts value held at back of list into *arg2 */

int BLReturnCurrent(button_list, button_type*);
/* Puts value held ad node pointed to by current pointer into *arg2 */


int BLSetCurrentToFront(button_list);
/* Sets current pointer to the value of the front pointer */

int BLSetCurrentToBack(button_list);
/* Sets current pointer to the value of the front pointer */

int BLAdvanceCurrent(button_list);
/* Moves the current pointer to the next node if possible */

int BLRetreatCurrent(button_list);
/* Moves the current pointer to the previous node if possible */


/* Functions for specific use. Pretty ugly and not very general */
/* Return 0 if succesful; 1 otherwise */

int BLAdvanceHead(button_list);
/* Makes the next node the front of the list */
/* Does not affect the length of the list */

int BLRetreatHead(button_list);
/* Makes the previous node the front of the list */
/* Does not affect the length of the list */

int BLAdvanceTail(button_list);
/* Makes the next node the back of the list */
/* Does not affect the length of the list */

int BLRetreatTail(button_list);
/* Makes the previous node the back of the list */
/* Does not affect the length of the list */

int BLResetHeadAndTail(button_list);
/* Makes the head and tail point to their 'correct' positions */


#endif