main.asm

; Basic Syntax for Assembly
; -------------------------

; An assembly program can be divided into three sections:
; The data section, the bss section, and the text section.

; The Data Section
; ----------------

; The data section is used for declaring initialized data or constants. This data does not change at
; runtime. You can declare various constant values, file names, or buffer size, in this section.

; The syntax for declaring data section is:

section.data

; The BSS Section
; ---------------

; The bss section is used for declaring variables. The syntax for declaring bss section is:

section.bss
 
; The Text Section
; ----------------

; The text section is used for keeping the actual code. This section must begin with the declaration
; global _start, which tells the kernel where the program execution begins.

; The syntax for declaring text section is:

section.text
   global _start
_start:

; Assembly Language Statements
; ----------------------------

; Assembly language programs consist of three types of statements:
; Executable instructions or instructions, Assembler directives or pseudo-ops, and
; macros.

; The executable instructions or simply instructions tell the processor what to do. Each instruction
; consists of an operation code (opcode). Each executable instruction generates one machine
; language instruction.

; The assembler directives or pseudo-ops tell the assembler about the various aspects of the
; assembly process. These are non-executable and do not generate machine language instructions.
; Macros are basically a text substitution mechanism.

; Syntax of Assembly Language Statements
; --------------------------------------

; Assembly language statements are entered one statement per line. Each statement follows the following format:
; [label]   mnemonic   [operands]   [;comment]

; The fields in the square brackets are optional. A basic instruction has two parts, the first one is the
; name of the instruction (or the mnemonic), which is to be executed, and the second are the
; operands or the parameters of the command.

; Following are some examples of typical assembly language statements:

INC COUNT        ; Increment the memory variable COUNT

MOV TOTAL, 48    ; Transfer the value 48 in the 
                 ; memory variable TOTAL
					  
ADD AH, BH       ; Add the content of the 
                 ; BH register into the AH register
					  
AND MASK1, 128   ; Perform AND operation on the 
                 ; variable MASK1 and 128
					  
ADD MARKS, 10    ; Add 10 to the variable MARKS
MOV AL, 10       ; Transfer the value 10 to the AL register

; Hello World in Assembly
; -----------------------

section	.text
   global _start    
	
_start:	            
   mov	edx,len     
   mov	ecx,msg    
   mov	ebx,1       
   mov	eax,4       
   int	0x80        
	
   mov	eax,1       
   int	0x80        

section	.data
msg db 'Hello, world!', 0xa
len equ $ - msg