Getting MISRA 10.1 in Polyspace 2012a for Pointer to Structures.

I am getting the following MISRA(10.1) warning: Implicit conversion of the expression of underlying type'unsigned char' to the type 'signed int' that is not a wider integer type of the same signedness.

The code is as below:

#define ETH_BUFF_NOTUSED ((uint8)0U)

typedef struct Eth_BuffTableType

{

uint8* Eth_BuffPtr;     /* Pointer to the Transmit Buffer*/

uint8  Eth_BuffStatus;  /* Buffer status free or used */

uint8  Eth_StTxCnfn;    /* Tx confirmation requested */

uint8  Eth_FrameTxReq;  /* Request for frame transmission */

}Eth_BuffTableType;

static Eth_BuffTableType *Eth_TxBuffTablePtr;

uint8 TempVar;

(Eth_TxBuffTablePtr + TempVar)->Eth_BuffStatus = ETH_BUFF_NOTUSED;

Question: Why the pointer 'Eth_TxBuffTablePtr' is considered as a 'signed_int'.? Is there any option to make pointer to structures as unsigned while running MISRA checks?

Answer 1

[Karan]

Thanks Alex.

Answer 2

[Alexandre De Barros]

Hi Karan!

Polyspace refers here to the ISO C99 standard to define a pointer equivalent to an int, especially the paragraph 6.3.2.3, sections 5 and 6. But this leads to the violation of 10.1, like in your code. This is why we may change this behaviour for a future version. There is no option to make pointers unsigned but I can suggest you to add a code annotation in order to automatically justify and comment the rule 10.1 on this line. Follow this link for more information on code annotations: http://www.mathworks.fr/fr/help/bugfinder/ug/annotate-code-for-rule-violations.html

Alex