廢話說在前面
碼代碼的應該學數據結構都學過隊列。環形隊列是隊列的一種特殊形式,應用挺廣泛的。
因爲有太多文章關於這方面的內容,理論知識可以看別人的,下面寫得挺好的:
STM32進階之串口環形緩衝區實現
代碼實現
typedef struct ringBuff{
unsigned int in; //寫入的位置
unsigned int out; //讀出的位置
unsigned char buffer[RING_BUFF_SIZE]; //數據域
}stRingBuff;
/**
- @brief: 寫一字節的數據到環形隊列
- @param[in]: None
- @retval[out]: None
- @note:
- @author: AresXu
- @version: v1.0.0
*/
char WriteOneByteToRingBuffer(stRingBuff *ringBuf,char data)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(IsRingBufferFull(ringBuf)) //寫之前先判斷隊列是否寫滿
{
return FALSE;
}
ringBuf->buffer[ringBuf->in] = data;
ringBuf->in = (++ringBuf->in) % RING_BUFF_SIZE; //防止越界
return TRUE;
}
寫入數據時要判斷隊列是否滿,滿了肯定就不能寫入。
/**
- @brief: 判斷環形隊列是否滿
- @param[in]: None
- @retval[out]: None
- @note:
- @author: AresXu
- @version: v1.0.0
*/
bool IsRingBufferFull(stRingBuff *ringBuf)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(((ringBuf->in+1) % RING_BUFF_SIZE) == ringBuf->out)
{
// printf("Ring buffer is Full\r\n");
return TRUE;
}
return FALSE;
}
當寫滿時,讀寫位置也是相等,無法判斷是否寫滿。這種情況有兩種辦法解決:
/**
- @brief: 從環形隊列中讀一字節數據
- @param[in]: None
- @retval[out]: None
- @note:
- @author: AresXu
- @version: v1.0.0
*/
char ReadOneByteFromRingBuffer(stRingBuff *ringBuf,char *data)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(IsRingBufferEmpty(ringBuf)) //讀之前判斷隊列是否爲空
{
return FALSE;
}
*data = ringBuf->buffer[ringBuf->out];
ringBuf->out = (++ringBuf->out) % RING_BUFF_SIZE; //防止越界
return TRUE;
}
寫入位置和讀出位置相等時爲空
/**
- @brief: 判斷環形隊列是否空
- @param[in]: None
- @retval[out]: None
- @author: AresXu
- @version: v1.0.0
*/
bool IsRingBufferEmpty(stRingBuff *ringBuf)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(ringBuf->in == ringBuf->out) //寫入位置和讀出位置相等時爲空
{
// printf("Ring buffer is Empty\r\n");
return TRUE;
}
return FALSE;
}
/**
* @brief: 寫len個字節數據到環形隊列
* @param[in]: None
* @retval[out]: None
* @note:
* @author: AresXu
* @version: v1.0.0
*/
void WriteRingBuffer(stRingBuff *ringBuf,char *writeBuf,unsigned int len)
{
unsigned int i;
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
for(i = 0; i < len; i++)
{
WriteOneByteToRingBuffer(ringBuf,writeBuf[i]);
}
}
/**
* @brief: 從環形隊列讀出len個字節的數據
* @param[in]: None
* @retval[out]: None
* @note:
* @author: AresXu
* @version: v1.0.0
*/
void ReadRingBuffer(stRingBuff *ringBuf,char *readBuf,unsigned int len)
{
unsigned int i;
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
for(i = 0; i < len; i++)
{
ReadOneByteFromRingBuffer(ringBuf,&readBuf[i]);
}
}
- 獲取已經寫入隊列的數據長度
有這個方便知道接收完了要從隊列中讀出多少個數據。
/**
* @brief: 獲取已經寫入的長度
* @param[in]: None
* @retval[out]: None
* @note:
* @author: AresXu
* @version: v1.0.0
*/
int GetRingBufferLength(stRingBuff *ringBuf)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
return (ringBuf->in - ringBuf->out + RING_BUFF_SIZE) % RING_BUFF_SIZE;
}
畫個圖,畫畫就可以知道爲什麼這樣可以判斷寫入的長度。
到STM32上測試
- 串口接收部分:
static stRingBuff g_stRingBuffer = {0,0,0};
static u8 g_recvFinshFlag = 0;
stRingBuff *GetRingBufferStruct(void)
{
return &g_stRingBuffer;
}
u8 *IsUsart1RecvFinsh(void)
{
return &g_recvFinshFlag;
}
void USART1_IRQHandler(void) //串口1中斷服務程序
{
u8 res;
if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET) //接收中斷(接收到的數據必須是0x0d 0x0a結尾)
{
res = USART_ReceiveData(USART1); //讀取接收到的數據
WriteOneByteToRingBuffer(GetRingBufferStruct(),res);
}
if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET) //空閒中斷
{
USART_ReceiveData(USART1); //清除空閒中斷
g_recvFinshFlag = 1; //接收完成
}
}
- 主函數:
int main(void)
{
char readBuffer[100];
u16 t;
u16 len;
u16 times = 0;
delay_init(); //延時函數初始化
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //設置NVIC中斷分組2:2位搶佔優先級,2位響應優先級
uart_init(115200); //串口初始化爲115200
LED_Init(); //LED端口初始化
KEY_Init(); //初始化與按鍵連接的硬件接口
while(1)
{
times++;
if(*IsUsart1RecvFinsh())
{
ReadRingBuffer(GetRingBufferStruct(),readBuffer,GetRingBufferLength(GetRingBufferStruct()));
printf("%s",readBuffer);
memset(readBuffer,0,100);
*IsUsart1RecvFinsh() = 0;
}
if(times%500==0)
LED0=!LED0;
delay_ms(1);
}
}
- 串口收發測試