Very quick and straightforward function, returns 1 if byte c is a 80x86 command prefix (ES:, CS:, SS:, DS:, FS:, GS:, DATASIZE, ADDRSIZE, LOCK, REPNE, REP) and 0 otherwise. Attention, it doesn't distinguish the cases when byte is part of the SSE/SSE2 command!
int Isprefix(int c);
Parameters:
c - byte to verify.
See also: Issuspicious, Isfilling