說在前面

碼代碼的應(yīng)該學(xué)數(shù)據(jù)結(jié)構(gòu)都學(xué)過隊列。環(huán)形隊列是隊列的一種特殊形式，應(yīng)用挺廣泛的。因為有太多文章關(guān)于這方面的內(nèi)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(huán)形緩沖區(qū)實現(xiàn)

代碼實現(xiàn)

環(huán)形隊列數(shù)據(jù)結(jié)構(gòu)

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(shù)據(jù)域
}stRingBuff;

寫一字節(jié)數(shù)據(jù)到隊列

/**
?-?@brief:?????????寫一字節(jié)的數(shù)據(jù)到環(huán)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
");
????????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(shù)據(jù)時要判斷隊列是否滿，滿了肯定就不能寫入。

判斷隊列是否寫滿

/**
?-?@brief:?????????判斷環(huán)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
");
????????return;
????}
????
????if(((ringBuf->in+1)?%?RING_BUFF_SIZE)?==?ringBuf->out)
????{
//??printf("Ring?buffer?is?Full
");
????????return?TRUE;
????}
????return?FALSE;
}

當(dāng)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：

數(shù)據(jù)結(jié)構(gòu)增加一個變量來計數(shù)寫入數(shù)據(jù)的個數(shù)

像這種((ringBuf->in+1) % RING_BUFF_SIZE) == ringBuf->out，空出一個字節(jié)來不寫數(shù)據(jù)

讀一字節(jié)的數(shù)據(jù)

/**
?-?@brief:?????????從環(huán)形隊列中讀一字節(jié)數(shù)據(jù)
?-?@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
");
????????return;
????}
????
????if(IsRingBufferEmpty(ringBuf))????//讀之前判斷隊列是否為空
????{
????????return?FALSE;
????}

????*data?=?ringBuf->buffer[ringBuf->out];
????ringBuf->out?=?(++ringBuf->out)?%?RING_BUFF_SIZE;????//防止越界

????return?TRUE;
}?

判斷隊列是否為空寫入位置和讀出位置相等時為空

/**
?-?@brief:????????判斷環(huán)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
");
????????return;
????}
????
????if(ringBuf->in?==?ringBuf->out)???//寫入位置和讀出位置相等時為空
????{
//??printf("Ring?buffer?is?Empty
");
????????return?TRUE;
????}
????return?FALSE;
}

寫多個字節(jié)到隊列

/**
?*?@brief:?????????寫len個字節(jié)數(shù)據(jù)到環(huán)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
");
????????return;
????}
????
????for(i?=?0;?i?

	從隊列中讀出多個字節(jié)
/**
?*?@brief:?????????從環(huán)形隊列讀出len個字節(jié)的數(shù)據(jù)
?*?@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
");
????????return;
????}
????
????for(i?=?0;?i?

	獲取已經(jīng)寫入隊列的數(shù)據(jù)長度有這個方便知道接收完了要從隊列中讀出多少個數(shù)據(jù)。
/**
??*?@brief:?????????獲取已經(jīng)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
");
????????return;
????}

????return?(ringBuf->in?-?ringBuf->out?+?RING_BUFF_SIZE)?%?RING_BUFF_SIZE;
}


	畫個圖，畫畫就可以知道為什么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(wù)程序
{
?u8?res;

?if(USART_GetITStatus(USART1,?USART_IT_RXNE)?!=?RESET)??//接收中斷(接收到的數(shù)據(jù)必須是0x0d?0x0a結(jié)尾)
?{
??res?=?USART_ReceiveData(USART1);?//讀取接收到的數(shù)據(jù)
??WriteOneByteToRingBuffer(GetRingBufferStruct(),res);?
????}
?if(USART_GetITStatus(USART1,?USART_IT_IDLE)?!=?RESET)????????//空閑中斷
?{
??USART_ReceiveData(USART1);???????????//清除空閑中斷
??g_recvFinshFlag?=?1;??????????????????//接收完成
?}
}?


	主函數(shù)：
int?main(void)
{??
?char?readBuffer[100];
?u16?t;??
?u16?len;?
?u16?times?=?0;
?delay_init();???????//延時函數(shù)初始化???
?NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);?//設(shè)置NVIC中斷分組2:2位搶占優(yōu)先級，2位響應(yīng)優(yōu)先級
?uart_init(115200);??//串口初始化為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(fā)測試


	

	編輯：黃飛