What does mov eax do?

What does mov eax do?

The instruction mov eax, eax may be a no-operation code but that is not what you have here. You’re loading from memory, as indicated by the [] “contents-of” characters. It loads eax with the contents of memory (a 32-bit dword in this case) that is currently pointed to by eax .

What does MOV EBP ESP mean?

mov ebp, esp moves the current stack position into EBP which is the base of the stack. We now have a reference point that allows us to reference our local variables stored on the stack. The value of EBP now never changes.

What is mov eax in assembly language?

mov [eax], [ebx] would mean “move the contents of the memory location pointed to by ebx to the memory location pointed to be eax . That is a memory-to-memory move, which Intel does not support.

What is EBP ESP EAX?

EBP. 0xbfffffe0. Registers. stack pointer (ESP): register containing the address of the top of the stack base pointer (EBP): register containing the address of the bottom of the stack frame instruction pointer (EIP): register containing the address of the instruction to be executed Other examples: EAX (return value).

What does MOV do in assembly?

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 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 happens when you pop EBP?

On entry to your function, you push it (to save the value for the calling function). Then, you copy esp , the stack pointer, into ebp , so that ebp now points to your function’s stack frame. At the end of your function, you then pop ebp so that the calling function’s value is restored.

What is EAX in assembly?

eax is the 32-bit, “int” size register. It was added in 1985 during the transition to 32-bit processors with the 80386 CPU. I’m in the habit of using this register size, since they also work in 32 bit mode, although I’m trying to use the longer rax registers for everything. ax is the 16-bit, “short” size register.

What is EAX register used for?

EAX,AX,AH,AL : Called the Accumulator register. It is used for I/O port access, arithmetic, interrupt calls, etc…

What does ESP do in assembly?

ESP (the stack pointer) is decremented by push since the x86 stack grows down — i.e. the stack grows from high addresses to lower addresses. 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).

What does ESP point to?

The ESP register serves as an indirect memory operand pointing to the top of the stack at any time. As program adds data to the stack, the stack grows downward from high memory to low memory. When items removed from the stack, stack shrinks upward from low to high memory.

What are the limitations of MOV?

The MOV instruction has a few limitations: an immediate value cannot be moved into a segment register directly (i.e. mov ds,10) segment registers cannot be copied directly (i.e. mov es,ds) a memory location cannot be copied into another memory location (i.e. mov aNumber,aDigit)

What does the instruction mov eax do?

The instruction mov eax, eax may be a no-operation code but that is not what you have here. You’re loading from memory, as indicated by the [] “contents-of” characters. It loads eax with the contents of memory (a 32-bit dword in this case) that is currently pointed to by eax. As to possible uses, there are no doubt many.

Why is MOV DWORD [ESP + 4] split into two instructions?

This operation cannot be done at once (as in mov dword [esp + 4], dword [eax], cannot have two memory references in the same instruction), so it is split in two instructions: Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. Provide details and share your research! But avoid …

What does mov eax DWORD PTR[EAX] do?

What does mov eax, dword ptr [eax] do? I understand that dword ptr is a size directive that indicates the size of what is being moved where and I know that mov eax, eax is a form of nop code but what does this do? I think it swaps the address of eax with the hex value inside but I am not too sure or even know why this would happen.

What is the notation for MOV instruction?

We use the following notation: mov — Move (Opcodes: 88, 89, 8A, 8B, 8C, 8E.) 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).

https://www.youtube.com/watch?v=vcfQVwtoyHY