util.c

//*****************************************************************************
// util.c - Utility implementations
//
// AUTHOR: Minh Mai
//
// Utility include:
// + PRIORITY QUEUE Utility
//
//
//
//*****************************************************************************

#include "util.h"
//*****************************************************************************
//
// PROCESS PRORITY QUEUE FACILITY Implementations
// 
//
//*****************************************************************************

// Function to check priority and place element
void static check(struct process_t *process, struct queue_t *queue);

//*****************************************************************************
//
//! \External
//! 
//!	Initialize the process queue before using
//! \param pointer to the queue 
//!
//! \return none
//
//*****************************************************************************
void init_queue(struct queue_t *queue)
{
	queue->in = 0;
	queue->out = 0;
	queue->k = QUEUE_SIZE;
}
//*****************************************************************************
//
//! \External
//! Add new process into the queue
//!
//! \param pointer to the process
//! \param pointer to the queue
//!
//! \return none
//
//*****************************************************************************
void append(struct process_t *process, struct queue_t *queue)
{
	check(process,queue);
    queue->in = (queue->in + 1) % queue->k;
}
//*****************************************************************************
//
//! \External
//!
//! Take the highest priority process out of the queue
//!
//! \param pointer to the queue
//!
//! \return pointer to the process
//
//*****************************************************************************
struct process_t *take(struct queue_t *queue)
{
	struct process_t *w;
    /* if queue is empty then return NULL */
    if (queue->out == queue->in) return NULL;
    /* else return pointer to a process */
	w = &(queue->pool[queue->out]);
	queue->out = (queue->out + 1) % queue->k;
	return w;
}
//*****************************************************************************
//
//! \Internal
//!
//! Function to check priority of process and place process into the queue
//!
//! Process with highest priority will be placed in front of the queue
//!
//! \param process
//!
//! \return none
//
//*****************************************************************************
void static check(struct process_t *process, struct queue_t *queue)
{
    int i,j;
    for (i = queue->out; i <= queue->in; i++)
    {
        if (process->prio <= queue->pool[i].prio || queue->pool[i].pid == 0)
        {
            for (j = queue->in + 1; j > i; j--)
            {
                queue->pool[j] = queue->pool[j - 1];
            }
            queue->pool[i] = *process;
            return;
        }
    }
    queue->pool[i] = *process;
}