Easy maintenance table of identifier vs. text

Question

In our project we have hundreds of identifiers used for error codes, example:

#define SYS_FAIL_EXCEP_PREFETCH_ABORT       0
#define SYS_FAIL_EXCEP_DATA_ABORT       1
#define SYS_FAIL_EXCEP_RESET        2
#define SYS_FAIL_EXCEP_UNDEFINED        3
#define SYS_FAIL_EXCEP_RESERVED     4
#define SYS_FAIL_EXCEP_IRQ_UNVECTORED   5

One of our requirements is to print the name or text of the identifier. We are using a lookup table for this:

typedef struct HAL_Map_Text_ID_struct
{
    unsigned int        id;
    char const * const  text;
} HAL_Map_Text_ID_t;

static const HAL_Map_Text_ID_t  system_failure_text_id_map[] =
{
    //  ID          Text
    // The following text has the prefix SYS_FAIL_EXCEP_
    {SYS_FAIL_EXCEP_PREFETCH_ABORT,                          "PREFETCH_ABORT"},
    {SYS_FAIL_EXCEP_DATA_ABORT,                              "DATA_ABORT"},
    {SYS_FAIL_EXCEP_RESET,                                   "RESET"},
    {SYS_FAIL_EXCEP_UNDEFINED,                               "UNDEFINED"},
    {SYS_FAIL_EXCEP_RESERVED,                                "RESERVED"},
    {SYS_FAIL_EXCEP_IRQ_UNVECTORED,                          "IRQ_UNVECTORED"},
};

Our issue is that the table and the error code list can be out of sync when somebody adds an identifier but forgets to update the table.

Is there an idiom or other process where we can add an identifier and the table will be updated automatically?

We would prefer a solution where the identifiers are in a header file and the table is in a source file.

Also, if possible, the solution should be MISRA compliant.

(We are using C89 with IAR embedded workbench with target system using ARM7 processor.)

Answer 1

You can use a system of macros to help create a single point of identifier update that will also update your strings. However, this scheme converts your identifiers from macros to enumerated constants. I am typing this as I go, so it is untested:

#define SYS_FAIL_EXCEPTIONS \
   SYS_FAIL_EXCEP(PREFETCH_ABORT) \
   SYS_FAIL_EXCEP(DATA_ABORT) \
   SYS_FAIL_EXCEP(RESET) \
   SYS_FAIL_EXCEP(UNDEFINED) \
   SYS_FAIL_EXCEP(RESERVED) \
   SYS_FAIL_EXCEP(IRQ_UNVECTORED)

enum {
    #define SYS_FAIL_EXCEP(X) SYS_FAIL_EXCEP_##X,
    SYS_FAIL_EXCEPTIONS
    #undef SYS_FAIL_EXCEP
};

static const HAL_Map_Text_ID_t  system_failure_text_id_map[] = {
    #define SYS_FAIL_EXCEP(X) { SYS_FAIL_EXCEP_##X, #X },
    SYS_FAIL_EXCEPTIONS
    #undef SYS_FAIL_EXCEP
};

If using an enum is not acceptable, and you must use #define macros, the alternative to this approach would be to use a text file to capture these exception definitions. Then, using a script, you can parse the text file and generate the appropriate C code for both the macro definitions as well as the string table.