What does Movl mean in assembly?

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What does Movl mean in assembly?

movl \%cs:var, êx. Move the contents of memory location var in the code segment (register \%cs) into number register êx.

What does MOVQ do in assembly?

The movq instruction moves the 1st argument (passed in \%rdi) to its place on the stack. The argument occupies the first stack position (stack entries are 8 bytes) after the base pointer (\%rbp).

What does Rax mean in assembly?

rax is the 64-bit, “long” size register. It was added in 2003 during the transition to 64-bit processors. eax is the 32-bit, “int” size register. It was added in 1985 during the transition to 32-bit processors with the 80386 CPU.

What is RBX Assembly?

For example, the instruction addq \%rax, \%rbx performs the computation \%rbx := \%rbx + \%rax . Data movement. These instructions move data between registers and memory. Almost all have one source operand and one destination operand; the source operand comes first.

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What does Movl instruction do?

The mov instruction (you have to learn these specifics for any instruction) does not care about the value stored in the location indicated by the target operand, but it will store a copy of the value of the source operand at the location indicated by the second operand, overwriting the previous value.

What is difference between MOV and Movl?

movq and movl are variations of the mov command (moving data to a memory location or a register). movq moves 8 bytes starting at the current specified memory address whereas movl moves 4 bytes starting at the current specificed memory address.

What is Pushq Assembly?

A push instruction pushes a value onto the stack. This both modifies the stack pointer (making it smaller) and modifies the stack segment (by moving data there). For instance, the instruction pushq X means: subq $8, \%rsp movq X, (\%rsp) And popq X undoes the effect of pushq X .

What does Movl do to upper 4 bytes?

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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 \%Rax used for?

The RAX register is used for return values in functions regardless of whether you’re working with Objective-C or Swift.

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