What is the opcode for MOV?

What is the opcode for MOV?

“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 does MOV do in x86?

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 assembly x64?

For years, PC programmers used x86 assembly to write performance-critical code. x64 is a generic name for the 64-bit extensions to Intel‟s and AMD‟s 32-bit x86 instruction set architecture (ISA). AMD introduced the first version of x64, initially called x86-64 and later renamed AMD64.

What is MOV instruction?

The MOV instruction moves data bytes between the two specified operands. The byte specified by the second operand is copied to the location specified by the first operand. The source data byte is not affected.

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.

What is an EAX?

A. E. (Environmental Audio Extensions) Sound card functions that reproduce the reverberation effects heard in different environments. Developed by Creative Labs, EAX provides an extension to the Windows DirectSound and OpenAL programming interfaces.

What does MOV mean in arm?

The MOV instruction copies the value of Operand2 into Rd . The MVN instruction takes the value of Operand2 , performs a bitwise logical NOT operation on the value, and places the result into Rd . In certain circumstances, the assembler can substitute MVN for MOV , or MOV for MVN .

What is Mrs in arm?

Usage. The MRS instruction transfers the contents of VFPsysreg into Rd . The MSR instruction transfers the contents of Rd into VFPsysreg .

What is RSB in arm?

The RSB instruction subtracts the value in Rn from the value of Operand2 . This is useful because of the wide range of options for Operand2 . In certain circumstances, the assembler can substitute one instruction for another.

What is the opcode for move 0xC0?

I am aware of http://ref.x86asm.net/, but looking at 48 opcodes, I don’t see anything that resembles a move. Actually, mov is 0xc7 there; 0x48 is, in this case, a long mode REX.W prefix. Answering also the question in comments: 0xc0 is b11000000.

What are the opcodes in the x86-64 instruction set?

The x86-64 instruction set defines many opcodes and many ways to encode them, depending on several factors. Legacy (and x87) opcodes consist of, in this order: opcode. Certain instructions (most notably the SIMD instructions) require a mandatory prefix (0x66, 0xF2 or 0xF3), which looks like a normal modifier prefix.

Can MOV be used to load the CS register?

Both operands must be the same size, which can be a byte, a word, a doubleword, or a quadword. The MOV instruction cannot be used to load the CS register. Attempting to do so results in an invalid opcode exception (#UD).

When does a Vex/XOP prefix need to be encoded?

A VEX/XOP prefix must be encoded when: when using 128-bit XMM destination registers, bits 128-255 of the corresponding YMM register must be cleared. A VEX/XOP prefix must not be encoded when: when using 128-bit XMM destination registers, bits 128-255 of the corresponding YMM register must not be changed.