What is movl
What is Movl in assembly language?
Assuming you are using GAS assembly language mnemonics for an Intel CPU, then: movq moves a quadword (64-bits) from source to destination. movl moves a long (32-bits) from source to destination.
What does Movl do to upper 4 bytes?
movl will write into all 4 bytes. In your example, it’ll zero out the upper 3 bytes, and put 1 in the lowest byte.
What is MOVQ?
movq (assuming you’re talking about x86) is a move of a quadword (64-bit value). This particular instruction: movq (%rsp), %rsp. looks very much like code that will walk up through stack frames.
What is Pushl?
Push Long. Description: The long word source operand is pushed onto the top of the stack. Notes: PUSHL is equivalent to MOVL src, -(SP), but is one byte shorter.
What is EIP register?
The EIP register (prior to transferring program control) contains the address of the instruction following the CALL instruction. When this address is pushed on the stack, it is referred to as the return instruction pointer or return address.
What is RBX register used for?
Registers
| Register | Purpose | Saved across calls |
|---|---|---|
| %rax | temp register; return value | No |
| %rbx | callee-saved | Yes |
| %rcx | used to pass 4th argument to functions | No |
| %rdx | used to pass 3rd argument to functions | No |
What does LEA instruction do?
The lea instruction places the address specified by its first operand into the register specified by its second operand. Note, the contents of the memory location are not loaded, only the effective address is computed and placed into the register.
What is Pushl EBP?
pushl %ebp stores the stack frame of the calling function on the stack. movl %esp, %ebp takes the current stack pointer and uses it as the frame for the called function.
What is x86 Popl?
The pop instruction removes the 4-byte data element from the top of the hardware-supported stack into the specified operand (i.e. register or memory location). It first moves the 4 bytes located at memory location [SP] into the specified register or memory location, and then increments SP by 4.
What is the difference between LES and LDS instruction?
lds means Load pointer using DS and likewise les means Load pointer using ES.
What is the purpose of LEA instruction in 8086?
LEA − Used to load the address of operand into the provided register.
What is Nopl instruction?
3 Answers. 3. 47. NOP is a one-byte “do nothing” operation, quite literally “no operation”. NOPW, NOPL, etc.. are the equivalent do-nothings, but take up word and long-sized bytes.
What is the difference between the LDS and LSS?
LSS (Load Pointer Using SS) operates identically to LDS except that SS receives the segment selector rather than DS. This instruction is especially important, because it allows the two registers that identify the stack (SS:ESP) to be changed in one uninterruptible operation.
What is DS register?
A 16-bit Data Segment register or DS register stores the starting address of the data segment. Stack Segment − It contains data and return addresses of procedures or subroutines. It is implemented as a ‘stack’ data structure. The Stack Segment register or SS register stores the starting address of the stack.
What is the difference between LDS and LES when should each be used?
lds means Load pointer using DS and likewise les means Load pointer using ES.
What is microprocessor LAHF?
LAHF stands for Load AH from Flags and SAHF stands for Store AH into Flags. LAHF & SAHF are used to load and store instructions for certain status flags. Instructions are basic commands composed of one or more symbols that that are passed to a CPU as input.
What is arithmetic and logic instructions?
The arithmetic instructions define the set of operations performed by the processor Arithmetic Logic Unit (ALU). The arithmetic instructions are further classified into binary, decimal, logical, shift/rotate, and bit/byte manipulation instructions.