queue.c

用LPC936实现通过SPI扩展多个串口,在这里实现了对多个通道的管理,C代码,

#include "queue.h"

bit queue_input(Queue idata *queue,char c) reentrant{
	if(queue_unused((*queue)) > 1){
		queue->buffer[queue->head] = c;
		queue->head = (queue->head+1)%queue->size;
		queue->length ++;
		return 1;
	}else return 0;
}

int queue_output(Queue idata *queue) reentrant{
	int c;

	if(queue->length == 0) return -1;
	else{
		c = queue->buffer[queue->tail];
		queue->tail = (queue->tail+1)%queue->size;
		queue->length --;
	}
	
	return c;
}