/*	PFAIR Mathematical functions */
#ifndef __UNC_PFAIR_MATH_H__
#define __UNC_PFAIR_MATH_H__

#include <linux/rt_param.h>
#include <asm/div64.h>
#include <linux/litmus.h>
#include <linux/sched.h>

/*	Type definition for our quantums */
typedef unsigned long long quantum_t;

/*
* This file defines  mathematical functions "ceiling", "floor",
* and PFAIR specific functions for computing the release and
* the deadline of a subtask, as well as tie breakers:
* b-bit and group deadline.
*/
static inline quantum_t FLOOR(quantum_t a, unsigned long b)
{
	BUG_ON( b == 0);
	do_div(a, b);
	return a;	
}
static inline quantum_t CEIL(quantum_t a, unsigned long  b)
{
	quantum_t t = FLOOR(a, b);
	return (quantum_t)((t * b == a) ? t : (t + 1));
}


/*
*	invariant - i-1=get_passed_quanta(t)
*
*	release time of i-th subtask of j-th job is
*	r_{ij}+\lfloor i-1/wt(T) \rfloor
*	This operation should be robust to wrap-around
*	so we can compare the result with jiffies safely
*/
static inline quantum_t release_time(struct task_struct * t)
{
	quantum_t e = get_exec_cost(t);
	quantum_t p = get_rt_period(t);
	return FLOOR((get_passed_quanta(t)) * p, e);
}
/*
*	deadline time of i-th subtask of j-th job is
*	r_{ij}+\lceil i/wt(T) \rceil
*	This operation should be robust to wrap-around
*	so we can compare the result with jiffies safely
*/
static inline quantum_t pfair_deadline(struct task_struct * t)
{
	quantum_t e = get_exec_cost(t);
	quantum_t p = get_rt_period(t);
	return CEIL((get_passed_quanta(t) + 1) * p, e);
}
/*	In PFAIR b-bit is defined as 
*	\lceil i/wt(T) \rceil-\lfloor i/wt(T) \rfloor
*/
static inline int b_bit(struct task_struct *t)
{
	quantum_t e = get_exec_cost(t);
	quantum_t p = get_rt_period(t);
	return CEIL((get_passed_quanta(t) + 1) * p, e)-
		FLOOR((get_passed_quanta(t) + 1) * p, e);
}
/*
*	Group deadline 
*/
static inline quantum_t group_deadline(struct task_struct * t)
{
	quantum_t p = get_rt_period(t);
	quantum_t e = get_exec_cost(t);
	quantum_t stage1 = CEIL((get_passed_quanta(t) + 1) * p, e);
	quantum_t stage2 = CEIL(stage1 * (p - e), p);
	return CEIL(stage2 * p, p - e);
}

#endif /*	__UNC_PFAIR_MATH_H__	*/