mirror of
https://github.com/yourtion/30dayMakeOS.git
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58 lines
1.0 KiB
C
58 lines
1.0 KiB
C
/* FIFO */
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#include "bootpack.h"
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#define FLAGS_OVERRUN 0x0001
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void fifo32_init(struct FIFO32 *fifo, int size, int *buf)
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/* FIFO缓冲区的初始化*/
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{
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fifo->size = size;
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fifo->buf = buf;
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fifo->free = size; /*空*/
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fifo->flags = 0;
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fifo->p = 0; /*写入位置*/
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fifo->q = 0; /*读取位置*/
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return;
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}
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int fifo32_put(struct FIFO32 *fifo, int data)
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/*给FIFO发送数据并储存在FIFO中*/
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{
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if (fifo->free == 0) {
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/*没有空余空间，溢出*/
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fifo->flags |= FLAGS_OVERRUN;
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return -1;
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}
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fifo->buf[fifo->p] = data;
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fifo->p++;
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if (fifo->p == fifo->size) {
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fifo->p = 0;
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}
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fifo->free--;
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return 0;
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}
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int fifo32_get(struct FIFO32 *fifo)
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/*从FIFO取得一个数据*/
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{
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int data;
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if (fifo->free == fifo->size) {
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/*当缓冲区为空的情况下返回-1*/
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return -1;
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}
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data = fifo->buf[fifo->q];
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fifo->q++;
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if (fifo->q == fifo->size) {
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fifo->q = 0;
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}
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fifo->free++;
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return data;
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}
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int fifo32_status(struct FIFO32 *fifo)
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/*报告已经存储了多少数据*/
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{
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return fifo->size - fifo->free;
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}
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