Register Addressing Mode in Assembly Language
What is Register Addressing Mode Syntax and Instruction
Register addressing mode is a type of memory addressing that uses processor registers to store data and instructions. It's used in assembly language programming as a way to quickly access data and instructions stored in the processor's registers. The syntax for register addressing mode instruction is quite simple, consisting of two parts: the destination register and the source register. The destination register is the instruction's target, while the source register is the register that contains the data or instruction to be accessed.
As an example, let's take the following instruction: MOV R1, R2. In this instruction, the destination register is R1, and the source register is R2. This instruction will move the contents of R2 into R1. This instruction is just one of many that can be used in register addressing mode.
Register addressing mode program using Assembly Language using
Here is an example program written in assembly language using register addressing mode:
MOV R1, #10
move 10 into R1
MOV R2, #20
move 20 into R2
MOV R3, R1
move the value in R1 into R3
ADD R3, R2
add the value in R2 to R3
JMP 0x1234
jump to address 0x1234
This program will first move the value 10 into the register R1, then moves the value 20 into the register R2. Next, it will move the value in R1 into R3. Finally, it will add the value from R2 to the value in R3 and then jump to address 0x1234.
The syntax for register addressing mode depends on the specific instruction set architecture of the processor being used. Here's an example using the x86 assembly language syntax to move a value from one register to another:
mov eax, ebx
In this example, eax is the destination register and ebx is the source register. The instruction moves the value stored in ebx into eax.
Here's a simple program using register addressing mode to add two numbers together in x86 assembly language:
section .data
num1 dd 10
num2 dd 20
result dd ?
section .text
global _start
_start:
mov eax, [num1]
mov ebx, [num2]
add eax, ebx
mov [result], eax
; exit program
mov eax, 1
xor ebx, ebx
int 0x80
In this program, num1 and num2 are defined in the .data section as doubleword (32-bit) variables, and result is a variable to hold the sum of num1 and num2. In the .text section, the program loads the values of num1 and num2 into registers eax and ebx, respectively, adds them together using the add instruction, and stores the result in result using register addressing mode. Finally, the program exits using a system call.