[英]Converting struct to pointer of member type
嗨,我是一名學生,電子信息通訊技術,我在I2C項目中遇到了一些麻煩。 我正在使用FreeRTOS作為調度程序。 為了在任務之間傳遞數據,我使用了BaseType_t xQueueSend(QueueHandle_t xQueue, const void *pvItemToQueue, TickType_t xTicksToWait);
需要一個項目(在我的例子中是一個結構)的方法。 我有3種結構類型,1種是具有有效負載字段的大型機,第二種是有效負載請求(C-APDU格式),最后一個結構是響應有效負載(R-APDU格式)。
下面是我的結構示例。
// mainframe I2C
typedef struct I2CMainFrame
{
//RF or I2C host to M24SR64-Y:
//C-APDU M24SR64-Y to RF or I2C host: R-APDU
uint8_t DID;
uint8_t PCB; // PCB field
void *Payload; // Payload
uint8_t CRC1; // 2 CRC bytes
uint8_t CRC2;
} I2CMainFrame_t;
// payload request
typedef struct PayloadSend
{
uint8_t CLA; // Class byte 0x00: standard command 0xA2: ST comman
uint8_t INS; // Instruction byte
uint8_t P1; // Param Byte 1
uint8_t P2; // Param Byte 2
uint8_t LC; // Number of bytes of the Data field
uint8_t *Data; // Data bytes
uint8_t Le; // Number of bytes to be read in the M24SR64-Y memory
} PayloadSend_t;
// payload response
typedef struct PayloadGet
{
uint8_t *Data; // Pointer to data
uint8_t SW1; // status byte 1
uint8_t SW2; // status byte 2
} PayloadGet_t;
問題是當我想訪問數據時。 我需要傳遞一個指向方法的指針,該方法在I2C總線上逐字節寫入數據或可以計算CRC值,例如:
void CalculateCRC(uint8_t *data, size_t szLen, uint8_t *outputBuffer);
void WriteDataOnI2CBus(uint8_t *data, size_t szLen);
做這樣的事情可行嗎? 我嘗試了以下代碼:
I2CMainFrame_t mainframe;
PayloadSend_t payload;
void rtosUartTask(void)
{
//Fill payloaddata
uint8 data[] = {0xD2, 0x76, 0x00, 0x00, 0x85, 0x01, 0x01};
payload.CLA = 0x00; payload.INS = 0xA4; payload.P1 = 0x04;
payload.P2 = 0x00; payload.LC = 0x07;
payload.Data = data; payload.Le = 0x00;
//fill mainframe data
mainframe.DID = 0xAC; mainframe.PCB = 0x02;
mainframe.Payload = &payload;
//methode for passing struct to I2C task
xQueueSend(I2CQueue, &mainframe,0);
}
I2CMainFrame_t mainframe;
void rtosUartTask(void)
{
//Task manager starts this method when there is a item in the queue
xQueueReceive(I2CQueue, &mainframe, portMAX_DELAY);
//This doesnt work
uint8_t *pointerToStructMembers = &mainframe;
WriteDataOnI2CBus(pointerToStructMembers, sizeof(mainframe));
}
我在這里尋找正確的方向還是應該嘗試其他方法?
uint8_t *pointerToStructMembers = &mainframe;
您不能使用類型轉換,因為I2CMainFrame
包含指針成員void *Payload
。
您可以嘗試按以下步驟序列化mainframe
。
聲明一個uint8_t
數組,然后將內容單獨復制到其中。
uint8_t bufferedStructMembers[sizeof(I2CMainFrame_t) + sizeof (PayloadSend_t) + ((PayloadSend_t *)(mainframe.Payload))->LC];
bufferedStructMembers[0] = mainframe.DID;
bufferedStructMembers[1] = mainframe.PCB;
bufferedStructMembers[2] = ((PayloadSend_t *)(mainframe.Payload))->CLA;
bufferedStructMembers[3] = ((PayloadSend_t *)(mainframe.Payload))->INS;
bufferedStructMembers[4] = ((PayloadSend_t *)(mainframe.Payload))->P1;
bufferedStructMembers[5] = ((PayloadSend_t *)(mainframe.Payload))->P2;
bufferedStructMembers[6] = ((PayloadSend_t *)(mainframe.Payload))->LC;
memcpy(&bufferedStructMembers[7], ((PayloadSend_t *)(mainframe.Payload))->Data, ((PayloadSend_t *)(mainframe.Payload))->LC);
bufferedStructMembers[((PayloadSend_t *)(mainframe.Payload))->LC+7] = mainframe.Le;
bufferedStructMembers[((PayloadSend_t *)(mainframe.Payload))->LC+8] = mainframe.CRC1; // 2 CRC bytes
bufferedStructMembers[((PayloadSend_t *)(mainframe.Payload))->LC+9] = mainframe.CRC2;
WriteDataOnI2CBus(bufferedStructMembers, sizeof(mainframe));
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