Commonly Used Instructions

1. MOVE Instruction

• Purpose: Moves or copies data.

  • Immediate: MOV EAX, 0xABCD1234 (moves the immediate value 0xABCD1234 into EAX).

  • Register to Register: MOV EAX, EBX (copies the value in EBX to EAX).

  • Memory: MOV EAX, DWORD PTR [EBP-0xC] (moves a value from memory at [EBP-0xC] into EAX).

2. ADD and SUB Instructions

• ADD: Performs addition.

  • Example: ADD EAX, EBX (adds the value in EBX to EAX).

• SUB: Performs subtraction.

  • Example: SUB EAX, 0x10 (subtracts 0x10 from EAX).

3. INC and DEC Instructions

• INC: Increments an operand by one.

  • Example: INC EAX (increases the value in EAX by one).

• DEC: Decrements an operand by one.

  • Example: DEC EAX (decreases the value in EAX by one).

4. XOR Instruction

• Purpose: Performs bit-wise XOR operation.

  • Example: XOR EAX, EBX (XORs the value in EAX with EBX).

5. NOP Instruction

• Purpose: No Operation; does nothing.

  • Usage: Used for timing purposes or memory alignment.

6. Unconditional Jump

• Purpose: Transfers control to another code unconditionally.

  • Example: JMP LABEL (jumps to the instruction at LABEL).

7. Conditional Jump

• Purpose: Transfers control if a specified condition is met.

  • JE/JZ: Jump if Equal/Jump if Zero (checks if the Zero Flag is set).

    • Example: JE LABEL (jumps to LABEL if ZF is set).

  • JNE/JNZ: Jump if Not Equal/Jump if Not Zero (checks if the Zero Flag is not set).

    • Example: JNE LABEL (jumps to LABEL if ZF is not set).

8. CMP Instruction

• Purpose: Compares two operands.

  • Example: CMP EAX, EBX (compares EAX with EBX).

9. LOOP Instruction

• Purpose: Transfers control to a label and decrements the ECX register.

  • Usage: Continues looping until ECX reaches zero.

  • Example: LOOP LABEL (jumps to LABEL and decrements ECX until ECX is zero).