68 lines
1.4 KiB
C
68 lines
1.4 KiB
C
#include "palindromatic.h"
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static void pm_queue_init(queue_t *queue)
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{
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queue->front = queue->rear = -1;
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for(int i = 0; i<QUEUE_SZ; i++) queue->reqs[i] = NULL;
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}
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static long pm_queue_enqueue(queue_t *queue, request_t *req)
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{
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if((queue->front == 0 && queue->rear == QUEUE_SZ-1) || (queue->rear+1)%QUEUE_SZ == queue->front) return -1;
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else if(queue->front == -1)
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{
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queue->front = queue->rear = 0;
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queue->reqs[queue->rear] = req;
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}
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else if(queue->rear == QUEUE_SZ-1 && queue->front != 0)
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{
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queue->rear = 0;
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queue->reqs[queue->rear] = req;
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}
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else
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{
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queue->rear++;
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queue->reqs[queue->rear] = req;
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}
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return queue->rear;
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}
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static request_t *pm_queue_dequeue(queue_t *queue)
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{
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if(queue->front == -1) return NULL;
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request_t *req = queue->reqs[queue->front];
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queue->reqs[queue->front] = NULL;
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if(queue->front == queue->rear) queue->front = queue->rear = -1;
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else if(queue->front == QUEUE_SZ-1) queue->front = 0;
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else queue->front++;
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return req;
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}
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static request_t *pm_queue_peek(queue_t *queue)
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{
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if(queue->front == -1) return NULL;
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else return queue->reqs[queue->front];
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}
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static int pm_queue_count(queue_t *queue)
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{
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if(queue->front == -1)
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return 0;
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else if(queue->rear >= queue->front)
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return queue->rear-queue->front+1;
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else
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return QUEUE_SZ - queue->front + queue->rear + 1;
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} |