[General] Structure Copying Issue in Keil

[tdmicro]

hi,
we are trying to copy some data in a structure (IDE :keil , lang - cpp)
structure

typedef unsigned char U8;
typedef struct 
{
	U8 pD;
	U8 sD;
	U8 dD;
	U8* txdata;
}data_ID;
typedef struct 
{
	sObj Data;
	unsigned char ms;
	unsigned char status;
}zmtData;


 typedef struct //autogenerated structure 
 {
     ubyte cG;    
     ulong uD;       
     ulong uk;     
     ubyte ubData[8];  
     uword cR;  
 }sObj;

and the copying function is

Len=4;
 sObj rxData;
	data_ID *dataID = (data_ID *)malloc(sizeof(U8)*(Len+3));// Allocate memory for struct data_ID
	dataID->txdata = (U8*)malloc(sizeof(U8)*Len);
	read_data(&rxData);
 /*
 rxData.ubData value is 7,8,9,10,11,12,13,14
 */
	memcpy(dataID,rxData.ubData, sizeof(data_ID));//dataID=(data_ID*)rxData.ubData;

rxData.ubData[] value is 7,8,9,10,11,12,13,14
while copying from rxData.ubData[] to dataID, in watch window, we can see the following details
dataID-> pD= 7;
dataID-> sD= 8;
dataID-> dD= 9;
dataID-> txdata= 00 13 12 11;
but expected value is
dataID. txdata= 13 12 11 10;
while debuging the code, 3rd index value of rxData.ubData 10 is missing. so we thought it is because of structural padding and used #pragma pack(1)
then we are getting exception (classB_trap)

kindly help us to find out the mistake in the above code

 

[Easyrider83]

You have no understanding of pointers

data_ID *dataID = (data_ID *)malloc(sizeof(data_ID ));// Allocate memory for struct data_ID

After this txdata will still be a undefined pointer and have to be allocated next