is_code

#define MS_CLS  0x00000600             // Mask for typing
#define FF_CODE 0x00000600             // Code ?
#define FF_DATA 0x00000400             // Data ?
#define FF_TAIL 0x00000200             // Tail ?
#define FF_UNK  0x00000000             // Unknown ?

#define is_code(F)       ((F & MS_CLS) == FF_CODE) // is code byte?
#define is_data(F)       ((F & MS_CLS) == FF_DATA) // is data byte?
#define is_tail(F)       ((F & MS_CLS) == FF_TAIL) // is tail byte?
#define is_unknown(F)    ((F & MS_CLS) == FF_UNK)  // is unexplored byte?
#define is_head(F)       ((F & FF_DATA) != 0)      // is start of code/data?