Final

README.md

@@ -7,18 +7,23 @@ A Simple Trail on Assembly.
 1. Compilation
 
     ```sh
-    $ nasm ./init.asm -f elf64 -o ./init.o
+    $ nasm ./init-01.asm -f elf64 [-o ./init-01.o]
     ```
 
 2. Linking
 
     ```sh
-    $ ld -s ./init.o -o ./init.out
+    $ ld -s ./init-01.o -o ./init-01.out
     ```
 
 3. Execution
 
     ```sh
-    $ ./init.out
+    $ ./init-01.out
     Holax, sekai!
+    39
+    Sharing (the World)
+    We're Sharing an Endless Love
     ```
+
+    (The part in brackets`()` is User's input.)

init-01.asm

@@ -0,0 +1,79 @@
+section .data
+	txt0	db	0xa, 0
+	txt1	db	"Sharing", 0x20, 0
+	txt	db	"Holax, Sekai!", 0xa, 0
+	txt2	db	"We're Sharing an Endless Love", 0xa, 0
+	dig	db	0
+
+section .bss
+	inst	resb	16
+
+section .text
+	global	_start
+
+%macro	exit	1		; Declaring the Name and the Num of Parameters of the Macro
+	mov	rax,	60	; Declaring the Function we're to call is `sys_exit`
+	mov	rdi,	%1	; `%[k]` means the k-th Parameter
+	syscall			; Calling the Function `sys_exit`
+%endmacro
+
+_start:
+	call	_printext
+	mov	rax,	3
+	call	_printdgrax
+	mov	rax,	9
+	call	_printdgrax
+	mov	rax,	txt0
+	call	_printstrax
+	mov	rax,	txt1
+	call	_printstrax
+	call	_readstr
+	mov	rax,	txt2
+	call	_printstrax
+	exit	0		; Process of exiting the Program
+
+_printext:			; A Sub-routine calling the Function `sys_write` to print the Bytes to which `rax` pointed
+	mov	rax,	1	; Declaring the Function we're to call is `sys_read`
+	mov	rdi,	1
+	mov	rsi,	txt
+	mov	rdx,	14
+	syscall
+	ret
+
+_readstr:			; A Sub-routine calling the Function `sys_read`(?) to read the String which the User inputs then stored it in `inst`
+	mov	rax,	0	; Declaring the Function we're to call is `sys_read`
+	mov	rdi,	0
+	mov	rsi,	inst
+	mov	rdx,	16
+	syscall
+	ret
+
+_printdgrax:
+	add	rax, 	48	; Add 48 to the Value of `rax`, which refers to the ascii of any digit
+	mov	[dig],	al	; Temporarily storing the Byte of the Digit in `[dig]` from `al`
+	mov	rax,	1
+	mov	rdi,	1
+	mov	rsi,	dig
+	mov	rdx,	1
+	syscall
+	ret
+
+;input: rax as a pointer to the specified string
+;output: print string as rax
+_printstrax:
+	push	rax		; Pushing the Value of `rax` into the Stack
+	mov	rbx,	0	; Setting the Value of `rbx` to zero, for counting Length of the Bytes later
+_prloop:
+	inc	rax		; ++`rax`, which makes it point to the Byte next to the one pointed to previously
+	inc	rbx		; ++`rbx`, which means the Length it recorded is added by one
+	mov	ch,	[rax]	; Temporarily storing the Byte in `cl` (or using `ch` is also proper), which `rax` pointed to, for being compared to zero later
+	cmp	ch,	0	; Compare the Byte to zero,
+	jne	_prloop		; * if the result is not equal, go back to `_prloop` (`jne` == "Jump when Not Equal")
+				; * otherwise, execute the program below:
+	mov	rax,	1	; Declaring the Function we're to call is `sys_write`, like every time we called it previously
+	mov	rdi,	1	;
+	pop	rsi		; The top of the Stack should be pushed from `rax` previously, which means it refers to the Starter of the String
+				; Now we pop it to `rsi`
+	mov	rdx,	rbx	; (Actually we can also operate on `rdx` directly only in this case, nevertheless operating on `rbx` before copying to `rdx` is more of safety
+	syscall
+	ret