/**
 * Declaration of the entry point functions used by a new context
 */
typedef void (CtxFunc)(void *ptr);

/**
 * CPU Context declaration
 */
enum CtxState {CtxInit, CtxOpen, CtxRunning, CtxClose} ;
struct CPUCtx {
	unsigned int  magic;      /* Magic word allowing struct init check */
	enum CtxState status;     /* is the context ready to use ? */
	
	CtxFunc       *entryFunc; /* address of the first called function */
	void          *entryArgs; /* address of the associated arguments */
	
	unsigned char *savedESP;  /* current intel x86 stack pointer */
	unsigned char *savedEBP;  /* current intel x86 base pointer */
	unsigned char *stack;     /* address for the linked stack */
	struct CPUCtx *next;      /* next Context */
} ;

int yield();

/**
 *
 */
void initMainCtx( struct CPUCtx *theCtx /* the "main" context */) ;

/**
 *
 */
void openCtx( struct CPUCtx *theCtx,   /* the context */
                       int stackSize,  /* size (in byte) of the associated stack */
                       CtxFunc *fct,   /* entry point for this context */
                       void *arg) ;    /* starting arguments */

/**
 * switch from oldCtx context to newCtx context
 */
volatile int switchToCtx(struct CPUCtx *newCtx) ;