Question

EAX 1CB2 H, EBX = 952 D, ECX - 1275 D, EDX -300 D What will be value stored in the four registers after executing the following instructions? Each group of instructions is executed independently from the initial values given above. Please also show which flag (zero, carry, sign) may be influenced. Hint you can test it in NSAM. a) and CL, AH b) shr CX, 3 c) or CL, 0D H not CL d) rol CX, 3 cmp DX, CX ) test AH, AL

Answer 1

952 in decimal = 3B8 in hex

-1275 in decimal = FFFFFB05 (1’s are added in the beginning since it is negative value)

-300 in decimal = FFFFFED4 (1’s are added in the beginning since it is negative value)

and CL,AH FLAGS Z, C, S ЕCX FFFFFB05 FFFFFED4 FFFFFB04 FFFFFED4 EAX EBX EDX Before execution ox1CB2 0x3B8 After execution 0x1CB2 000 Охзв8 000 SHR CX, 3 FLAGS Z, C,S EAX EBX ЕСX EDX Before execution Ox1CB2 After execution Ox1CB2 OX3B8 FFFFFB05 FFFFFED4 Ox3B8 FFFF1F60 FFFFFED4 000 010 OR CL, ODH FLAGS Z, C, S EAX ЕBХ ЕСX EDX Before execution OX1CB2 After execution Ox1CB2 Ox3B8 FFFFFB05 FFFFFED4 Ox3B8 FFFFFBOD FFFFFED4 000 000 NOT CL FLAGS Z, C,S EAX EBX ЕСX EDX Before execution| OX1CB2 After execution OX1CB2 FFFFFB05 FFFFFED4 FFFFFBF2 FFFFFED4 0x3B8 000 Охзв8 000

ROL CX, 3 FLAGS Z, C, S ЕСX Ox3B8 FFFFFB05 FFFFFED4 EAX EBX EDX Before execution ox1CB2 After execution Ox1CB2 0x3B8 FFFFD82F FFFFFED4| 000 010 CMP DX,CX FLAGS Z, C, S EAX EBX ЕСX EDX Before execution Ox1CB2 After execution Ox1CB2 0x3B8 Ox3B8 FFFFFB05 FFFFFED4 FFFFFB05 FFFFFED4 000 000 TEST AH,AL FLAGS Z, C, S EAX EBX ЕСX EDX Before execution Ox1CB2 After execution 0x1CB2 Ox3B8 FFFFFB05 FFFFFED4 Ox3B8 FFFFFB05 FFFFFED4 000 000