Assembly Assignment

; Assembly work for Asssignment
;
; Course: Assembly Programming for all Platforms
;
; Copyright (C) 2022 UNIXn3rdV


; Macros takes 2 arguments and will be required to use
;
;
%macro print_line 2

    mov eax, 4      ; sys_write call
    mov ebx, 1      ; use a file descriptor (fd) - Screen
    mov ecx, %1     ; Data in to buffer
    mov edx, %2     ; send no of bytes to buffer

    int 0x80        ; call kernel interupt

;  Sys_write system call (EAX is 32 Bit while RAX is 64 Bit)
;
; EAX   Arg1 (EBX)  Arg2 (ECX)    Arg3 (EDX)
;  4      fd         String     Bytes of string
;
%endmacro

%macro print_Linux_lines 2

    mov eax, 4      ; sys_write call
    mov ebx, 1      ; use a file descriptor (fd) - Screen
    mov ecx, %1     ; Data in to buffer
    mov edx, %2     ; send no of bytes to buffer
    int 0x80        ; call kernel interupt

    ; Add a newline after print
    mov eax, 4
    mov ebx, 1
    mov ecx, newline
    mov edx, nllen
    int 0x80


%endmacro

; similar to the C putchar
%macro putchar 2
    mov eax, 4
    mov ebx, 1
    mov ecx, %1
    mov edx, %2
    int 0x80

    ; Add a space after the charactor
    mov eax, 4
    mov ebx, 1
    mov ecx, space
    mov edx, splen
    int 0x80

%endmacro

%macro read_line 2

    mov eax, 3      ; sys_read call
    mov ebx, 1      ; use file descriptor (fd) - Keyboard
    mov ecx, %1     ; output buffer
    mov edx, %2     ; size

    int 0x80        ; call kernel interrupt


;  Sys_read system call
;
; EAX   Arg1 (EBX)  Arg2 (ECX)    Arg3 (EDX)
;  3      fd         Variable   Bytes of variable
;

%endmacro



; Data Section will contain values to be addressed in memory before
; compilation of the program
;

section .data

    newline: db ' ', 0xA        ; New line
    nllen: equ $-newline

    space: db ' ', 0 ; Space
    splen: equ $-space

    progn: db 'Assembly assignment program',0xA     ; Program name (db = define bytes)
    pglen: equ $-progn                              ; Program name length in bytes calculation

    copyr: db 'Copyright (C) 2022 UNIXnerd',0xA,0xA ; copyright message
    crlen: equ $-copyr                              ; copyright length in bytes calculation

    prompt1: db 'Please Enter your name: ', 0   ; Prompt a user
    prmptlen: equ $-prompt1

    hello: db 'Hello, ', 0  ; Hello
    helen: equ $-hello

    ASCIIShow: db 'Now we are going to show all non-extended ASCII Charactors', 0xA
    ASClen: equ $-ASCIIShow

    asm: db 'Made in Assembly (Linux)', 0
    asmlen: equ $-asm


; Section for variables reserving memory in bytes for future
; use in the program
;
section .bss
        name:  resb 20  ; reserve 20 bytes for a name  - for input
        char:  resb 5   ; this is for ascii charactor related
        no:    resb 2       ; Number to use for edx


; This is where most of code will be
section .text
    global _start


_start:

    print_line progn, pglen         ; Display Program name
    print_line copyr, crlen         ; Display Copyright
    print_line prompt1, prmptlen    ; Show Prompt
    read_line name, 20              ; Take input
    print_line newline, nllen       ; Line Spacing
    print_line hello, helen         ; Display Hello
    print_line name, 20             ; display name
    print_line newline, nllen       ; Line Spacing
    print_line ASCIIShow, ASClen    ; Display message on ASCII Charactor display
    print_line newline, nllen       ; Line Spacing

    ; Display ASCII Charactors
    mov esi, 48                     ; Start ASCII at 48
    call print_ascii
    print_line newline, nllen       ; Line Spacing
    print_line newline, nllen       ; Line Spacing

    mov edi, 1                      ; for printing linux line
    mov [no], edi
    call print_Linux
    print_line newline, nllen       ; Line Spacing



    call sys_exit                   ; exit the program


print_ascii:

    mov [char], esi                 ; put value in to variable
    putchar char, 1             ;

    inc esi
    ;add esi, 1
    cmp esi, 126                    ; 126 is final charactor
    jle print_ascii                 ; jump back to start of block until 126 is reached
    ret

print_Linux:
    mov [no], edi
    print_Linux_lines asm, [no]     ; no must be in brackets (Variable) or it will over run.
    inc edi
    cmp edi, asmlen             ; compare value with total length of linux line
    jle print_Linux
    ret

sys_exit:
    mov eax, 1          ; sys_exit call
    mov ebx, 0          ; show exit code 0
    int 0x80            ; interrupt the kernel
    ret