How to make C code to MISRA C:2012 compliance?

问题

I am validating MISRA C:2012 standard to my MCU code using PC-Lint. I got following errors.Here I posted a sample code where I got errors on condition statements.

1] unsigned integer literal without a 'U' suffix [MISRA 2012 Rule 7.2, required] S_LCB_100,

2] side effects on right hand of logical operator, '&&' [MISRA 2012 Rule 13.5, required] while(( 0x00000000 != List[Loop] ) && ( 0 != Counter ))

3] : a signed value and an unsigned value cannot be used together as operands to != [MISRA 2012 Rule 10.4, required] while(( 0x00000000 != List[Loop] ) && ( 0 != Counter ))

4] : a signed value and an unsigned value cannot be used together as operands to != [MISRA 2012 Rule 10.4, required] while(( 0x00000000 != List[Loop] ) && ( 0 != Counter ))

5] an unsigned value and a signed value cannot be used together as operands to == [MISRA 2012 Rule 10.4, required] if ( List[Loop] == 0x00000000 )

How can I make it MISRA C:2012 compliance?

typedef unsigned char UINT8;
typedef unsigned char BYTE;  
typedef unsigned long int UINT32; 
#define S_LCB_100 0xF0BB12DE;
#define MULTI 0x1A;
volatile static BYTE Counter = 0;
static UINT8 Loop = 0;    
static UINT32 List[]=  
{
    S_LCB_100,
    0x00000000,
};
while(( 0x00000000 != List[Loop] ) && ( 0 != Counter ))
{
 .......some code
}
if ( List[Loop] == 0x00000000 )
{
.....some code
}

回答1:

General remarks:

Before worrying about MISRA-C compliance, get the code to compile on a C compiler.
Then make sure you have the MISRA-C:2012 document available or you simply cannot work with MISRA.
Get rid of nonsense like "Yoda conditions".
Get rid of custom typedefs and use stdint.h. If you are on C90 then typedef with the names used by stdint.h.

1] unsigned integer literal without a 'U' suffix [MISRA 2012 Rule 7.2, required] S_LCB_100,

Pretty self-explaining. Add U or u to integer constants that should be unsigned. Read rule 7.2 for details.

2] side effects on right hand of logical operator, '&&' [MISRA 2012 Rule 13.5, required] while(( 0x00000000 != List[Loop] ) && ( 0 != Counter ))

Counter is voltatile-qualified and accessing it is a side-effect. So it should not exist inside complex expressions in general, and particularly not on the right hand side of a boolean && expression - that's quite questionable code. In this case you could simply rewrite the code as this:

uint32_t count = (uint32_t)Counter;

while((count != 0u) && (List[Loop] != 0u))
{
  ...
  count = (uint32_t)Counter; // read volatile variable in an expression of its own
}

3] a signed value and an unsigned value cannot be used together as operands to != [MISRA 2012 Rule 10.4, required] while(( 0x00000000 != List[Loop] ) && ( 0 != Counter ))

This is because Counter is declared as BYTE. Drop all such home-brewed crap types and declare it as uint8_t instead. Then use the while form as shown above. Use u suffix. This should fix 2) to 5).

来源：https://stackoverflow.com/questions/54084453/how-to-make-c-code-to-misra-c2012-compliance

标签

embedded

misra