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#include <stdint.h>
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#include <string.h>
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#define cb_item_t uint8_t // item type
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#define CB_ITEM_N 1024 // item number，实际可存入数据少一个，留一个空位表示满，以区别于空
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typedef struct
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{
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cb_item_t buf[CB_ITEM_N];
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int wrptr; // 写指针
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int rdptr; // 读指针
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} CircleBuffer_t;
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/* Element Count in buffer */
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static int CirBuf_Count(CircleBuffer_t *cirbuf)
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{
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return (cirbuf->wrptr - cirbuf->rdptr) & (CB_ITEM_N - 1);
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}
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/* Space available in buffer */
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static int CirBuf_Space(CircleBuffer_t *cirbuf)
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{
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return (cirbuf->rdptr - cirbuf->wrptr - 1) & (CB_ITEM_N - 1);
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}
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static int CirBuf_Empty(CircleBuffer_t *cirbuf)
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{
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return CirBuf_Count(cirbuf) == 0;
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}
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static int CirBuf_Full(CircleBuffer_t *cirbuf)
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{
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return CirBuf_Space(cirbuf) == 0;
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}
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static void CirBuf_Clear(CircleBuffer_t *cirbuf)
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{
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cirbuf->rdptr = cirbuf->wrptr;
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}
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static int CirBuf_Write(CircleBuffer_t *cirbuf, cb_item_t *buf, int num)
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{
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int n;
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if(cirbuf->wrptr >= cirbuf->rdptr)
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{
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n = CB_ITEM_N - cirbuf->wrptr;
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if(cirbuf->rdptr == 0)
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n -= 1;
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n = (n >= num) ? num : n;
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memcpy(&cirbuf->buf[cirbuf->wrptr], buf, n * sizeof(cb_item_t));
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cirbuf->wrptr = (cirbuf->wrptr + n) % CB_ITEM_N;
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if((n == num) || CirBuf_Full(cirbuf))
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return n;
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else
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return n + CirBuf_Write(cirbuf, &buf[n], num - n);
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}
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else
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{
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n = CirBuf_Space(cirbuf);
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n = (n >= num) ? num : n;
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memcpy(&cirbuf->buf[cirbuf->wrptr], buf, n * sizeof(cb_item_t));
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cirbuf->wrptr += n;
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return n;
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}
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}
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static int CirBuf_Read(CircleBuffer_t *cirbuf, cb_item_t *buf, int num)
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{
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int n;
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if(cirbuf->wrptr >= cirbuf->rdptr)
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{
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n = CirBuf_Count(cirbuf);
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n = (n >= num) ? num : n;
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memcpy(buf, &cirbuf->buf[cirbuf->rdptr], n * sizeof(cb_item_t));
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cirbuf->rdptr += n;
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return n;
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}
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else
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{
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n = CB_ITEM_N - cirbuf->rdptr;
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n = (n >= num) ? num : n;
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memcpy(buf, &cirbuf->buf[cirbuf->rdptr], n * sizeof(cb_item_t));
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cirbuf->rdptr = (cirbuf->rdptr + n) % CB_ITEM_N;
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if((n == num) || CirBuf_Empty(cirbuf))
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return n;
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else
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return n + CirBuf_Read(cirbuf, &buf[n], num - n);
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}
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}
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