Attempting to decode: f3 af 
iclass REPE_SCASD	category STRINGOP	ISA-extension BASE	ISA-set I386
instruction-length 2
operand-width 32
effective-operand-width 32
effective-address-width 32
stack-address-width 32
iform-enum-name REPE_SCASD
iform-enum-name-dispatch (zero based) 0
iclass-max-iform-dispatch 1
Nominal opcode position 1
Nominal opcode 0xaf
Operands
#   TYPE               DETAILS        VIS  RW       OC2 BITS BYTES NELEM ELEMSZ   ELEMTYPE   REGCLASS
#   ====               =======        ===  ==       === ==== ===== ===== ======   ========   ========
0   REG0              REG0=EAX SUPPRESSED   R         D   32     4     1     32        INT        GPR
1   MEM0           (see below) SUPPRESSED  CR         D   32     4     1     32        INT    INVALID
2  BASE0             BASE0=EDI SUPPRESSED RCW       ASZ   32     4     1     32        INT        GPR
3   REG1              REG1=ECX SUPPRESSED RCW       ASZ   32     4     1     32        INT        GPR
4   REG2           REG2=EFLAGS SUPPRESSED RCW         Y   32     4     1     32        INT      FLAGS
Memory Operands
  0    read SEG= ES BASE= EDI/GPR  ASZ0=32
  MemopBytes = 4
FLAGS:
   reads-rflags of-mod df-tst sf-mod zf-mod af-mod pf-mod cf-mod zf-tst 
       read:                         zf df  mask=0x440
    written:             of sf zf af pf cf  mask=0x8d5
  undefined:                                mask=0x0
READS ZF
ATTRIBUTES: FIXED_BASE0 REP 
REAL REP 	corresponding no-rep iclass: SCASD
F3 PREFIX
Number of legacy prefixes: 1 
ISA SET: [I386]