snake.h

snake game in avr snake game in avr

/*
** snake.h
**
** Written by Peter Sutton - October 2004
**
** Details of the snake
*/

#include <inttypes.h>

/* Directions */
#define UP 0
#define RIGHT 1
#define DOWN 2
#define LEFT 3

/* Possible results of an attempt to move the snake */
#define OUT_OF_BOUNDS -1
#define COLLISION -2
#define MOVE_OK 1
#define ATE_FOOD 2

/* The type that we use for positions */
typedef struct {
    unsigned char x;
    unsigned char y;
} posn_type;

/*  
** init_snake()
**
** Initialise the snake position. 
*/
void init_snake(void);

/*
** get_snake_head_position()
**
** Returns the position of the head of the snake
*/
posn_type get_snake_head_position(void);

/* move_snake()
**
** Attempt to move the snake by one in the current direction.
** Returns -1 if the snake has run into the edge or itself,
** 0 if the move is successful, 1 if the snake has eaten
** some food (and grown). If the snake has too many bends
** (i.e. the move would create an extra element beyond
** our element array then any attempt to turn is rejected.
*/
int8_t move_snake(void);

/* set_snake_dirn(direction)
**
**      Attempt to set snake direction to one of UP, DOWN, 
**      LEFT or RIGHT. Returns 1 if successful, 0 otherwise.
**      (Will fail if try and reverse snake - OK to continue
**      in same direction or turn 90degrees.)
*/
int8_t set_snake_dirn(int8_t dirn);