GNU Info

(nasm.info)Section B.4.24

---

Next: Section B.4.25 Prev: Section B.4.23 Up: Section B.4

---

Enter node , (file) or (file)node

B.4.24. `CMP': Compare Integers
-------------------------------

     CMP r/m8,reg8                 ; 38 /r                [8086]
     CMP r/m16,reg16               ; o16 39 /r            [8086]
     CMP r/m32,reg32               ; o32 39 /r            [386]

     CMP reg8,r/m8                 ; 3A /r                [8086]
     CMP reg16,r/m16               ; o16 3B /r            [8086]
     CMP reg32,r/m32               ; o32 3B /r            [386]

     CMP r/m8,imm8                 ; 80 /0 ib             [8086]
     CMP r/m16,imm16               ; o16 81 /0 iw         [8086]
     CMP r/m32,imm32               ; o32 81 /0 id         [386]

     CMP r/m16,imm8                ; o16 83 /0 ib         [8086]
     CMP r/m32,imm8                ; o32 83 /0 ib         [386]

     CMP AL,imm8                   ; 3C ib                [8086]
     CMP AX,imm16                  ; o16 3D iw            [8086]
     CMP EAX,imm32                 ; o32 3D id            [386]

   `CMP' performs a `mental' subtraction of its second operand from its
first operand, and affects the flags as if the subtraction had taken
place, but does not store the result of the subtraction anywhere.

   In the forms with an 8-bit immediate second operand and a longer
first operand, the second operand is considered to be signed, and is
sign- extended to the length of the first operand. In these cases, the
`BYTE' qualifier is necessary to force NASM to generate this form of
the instruction.

   The destination operand can be a register or a memory location. The
source can be a register, memory location or an immediate value of the
same size as the destination.