What is the use of test instruction?
Table of Contents
What is the use of test instruction?
In the x86 assembly language, the TEST instruction performs a bitwise AND on two operands. The flags SF , ZF , PF are modified while the result of the AND is discarded. The OF and CF flags are set to 0 , while AF flag is undefined.
What are the instructions used in assembly language programming?
A typical assembly language consists of 3 types of instruction statements that are used to define program operations: Opcode mnemonics. Data definitions. Assembly directives.
What is the difference between test and CMP?
This is a reasonable question to ask, because cmp is an arithmetic operation, (it performs a subtraction and discards the result,) while test is a logical operation, (it performs a bitwise AND and discards the result,) so one could reasonably suspect that they may modify the Flags register differently.
What is RBX register used for?
Registers
| Register | Purpose | Saved across calls |
|---|---|---|
| \%rbx | callee-saved | Yes |
| \%rcx | used to pass 4th argument to functions | No |
| \%rdx | used to pass 3rd argument to functions | No |
| \%rsp | stack pointer | Yes |
How do you write test instructions?
- Overview.
- Make Your Instructions Specific. Example.
- Clearly State Your Goals in Your Instructions. Example.
- Provide a Note Encouraging Students to Seek Help for Instructions That Are Unclear to Them. Example.
- Provide Instructions Within the Test Questions.
- Split Up Complex Test Instructions.
- Remember to Give Context.
- Conclusion.
Which instruction are used to test a register?
MOV instruction
These registers were accessed by variants of the MOV instruction. A test register may either be the source operand or the destination operand. The MOV instructions are defined in both real-address mode and protected mode. The test registers are privileged resources.
Which of the following instruction is an example of logical instructions?
Logical Operations
| Instruction Mnemonic | Example | Description |
|---|---|---|
| AND | AND EAX, 0ffffh | Performs bitwise logical AND |
| OR | OR EAX, 0fffffff0h | Performs bitwise logical OR |
| XOR | EBX, 0fffffff0h | Performs bitwise logical XOR |
| NOT | NOT [EAX] | Performs bitwise logical NOT |
What is instruction set with example?
An example of an instruction set is the x86 instruction set, which is common to find on computers today. Different computer processors can use almost the same instruction set while still having very different internal design. Both the Intel Pentium and AMD Athlon processors use nearly the same x86 instruction set.
What is cmp instruction in assembly language?
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.
What does JNE do in assembly?
The jnz (or jne) instruction is a conditional jump that follows a test. It jumps to the specified location if the Zero Flag (ZF) is cleared (0). jnz is commonly used to explicitly test for something not being equal to zero whereas jne is commonly found after a cmp instruction.
What is MOV instruction in assembly language?
The mov instruction copies the data item referred to by its second operand (i.e. register contents, memory contents, or a constant value) into the location referred to by its first operand (i.e. a register or memory).
What is the purpose of instruction pointer?
The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, is a processor register that indicates where a computer is in its program …