Conditional execution in assembly language is accomplished by several looping and branching instructions. These instructions can change the flow of control in a program. Conditional execution is observed in two scenarios −
Unconditional jump
This is performed by the JMP instruction. Conditional execution often involves a transfer of control to the address of an instruction that does not follow the currently executing instruction. Transfer of control may be forward, to execute a new set of instructions or backward, to re-execute the same steps.
Conditional jump
This is performed by a set of jump instructions j<condition> depending upon the condition. The conditional instructions transfer the control by breaking the sequential flow and they do it by changing the offset value in IP.
CMP Instruction
The CMP instruction compares two operands. It is generally used in conditional execution. This instruction basically subtracts one operand from the other for comparing whether the operands are equal or not. It does not disturb the destination or source operands. It is used along with the conditional jump instruction for decision making.
| JE/JZ | Jump Equal or Jump Zero | ZF |
| JNE/JNZ | Jump not Equal or Jump Not Zero | ZF |
| JG/JNLE | Jump Greater or Jump Not Less/Equal |
| JGE/JNL | Jump Greater/Equal or Jump Not Less |
| JL/JNGE | Jump Less or Jump Not Greater/Equal |
| JLE/JNG | Jump Less/Equal or Jump Not Greater |
CMP AL, BL JE EQUAL CMP AL, BH JE EQUAL CMP AL, CL JE EQUAL NON_EQUAL: EQUAL: