What does EAX mean in assembly language?

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What does EAX mean in assembly language?

It stands for a general purpose register. The 16 bit AX register can be addressed as AH (high byte) and AL (low byte). The EAX register is the 32 bit version of the AX register. The E stands for extended.

What is call in assembly language?

The call instruction is used to call a function. The CALL instruction performs two operations: It pushes the return address (address immediately after the CALL instruction) on the stack. It changes EIP to the call destination. This effectively transfers control to the call target and begins execution there.

What is EAX EBX?

The EAX, EBX, ECX, EDX, EBP, EDI, and ESI registers are all 32-bit general-purpose registers, used for temporary data storage and memory access. https://web.archive.org/web/20191114093028/https://gerardnico.com/computer/cpu/register/general. Some of CPU instructions modify specific registers.

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What is mov eax in assembly language?

“mov” is an instruction, encoded with the operation code or “opcode” 0xb8. Since mov takes an argument, the next 4 bytes are the constant to move into eax. The opcode 0xb9 moves a constant into ecx. 0xba moves a constant into edx.

What is EAX and ax?

EAX is the full 32-bit value AX is the lower 16-bits AL is the lower 8 bits AH is the bits 8 through 15 (zero-based) So AX is composed of AH:AL halves, and is itself the low half of EAX. (The upper half of EAX isn’t directly accessible as a 16-bit register; you can shift or rotate EAX if you want to get at it.)

What does EAX stand for register?

EAX register, a 32-bit processor register of x86 CPUs. Environmental Audio Extensions, a number of digital signal processing presets for audio, found in Sound Blaster sound cards.

What is XOR EAX EAX?

xor eax, eax is a faster way of setting eax to zero. This is happening because you’re returning zero. The in instruction is doing stuff with I/O ports. Basically reading a word of data from the port specified dx in and storing it in al .

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What is the EAX register?

eax. eax is a 32-bit general-purpose register with two common uses: to store the return value of a function and as a special register for certain calculations. It is technically a volatile register, since the value isn’t preserved. Instead, its value is set to the return value of a function before a function returns.

What does test EAX EAX do?

eax contains the return value of strcmp. test is like bitwise and except it only sets the flags. Anding a value with itself gives the same value, so test eax, eax sets the flags based on whatever eax contains. ZF is set when the result of an operation is zero.

What is EAX x86?

In 1985 Intel introduced 80386, the first 32-bit processor in the x86 line. The main registers were extended to 32 bits by adding an E prefix: EAX stood for extended AX . And AX now refers to the lower half of EAX , while AH and AL continue to refer to the two AX bytes. And that’s how EAX got its name.

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What is EDX and EAX?

The most common 64-bit register (used for operations such as division and multiplication) is edx:eax. This means that the 32-bits of edx are put in front of the 32-bits of eax, creating a double-long register, so to speak.

What does MOV EAX 4 mean?

; print a byte to stdout mov eax, 4 ; the system interprets 4 as “write” mov ebx, 1 ; standard output (print to terminal) mov ecx, variable ; pointer to the value being passed mov edx, 1 ; length of output (in bytes) int 0x80 ; call the kernel.

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