input.asm 08/25/2016

;executable name:   input.asm
;version:           1.0
;created date:      08/24/16
;last update:       08/25/16
;author:            Kevin M. Thomas
;description:       app that accepts only proper int input of 4 bytes
;run:               ./input
;compile:           nasm -f elf32 input.asm
;link:              ld -m elf_i386 -o input input.o

%include 'functions.asm'            ;include external library

SECTION .data                       ;initialized data section
    prompt_input db 'Enter 4 Numbers ONLY:  '
    prompt_inputLEN equ $ - prompt_input
    buffer times 4 db 0
    bufferLEN equ $ - buffer
    display_buffer db 'Buffer:  '
    display_bufferLEN equ $ - display_buffer

SECTION .bss                        ;unitialized data section
    kb_input resb 1

SECTION .text
    global _start

_start:
    nop                             ;for debugging purposes

    call clear_screen               ;cal clear_screen function

prompt_input_message:
    mov ecx, prompt_input           ;mov prompt_input to ECX
    mov edx, prompt_inputLEN        ;mov LEN to EDX
    call write_message              ;call write_message function

    call canonical_off              ;call canonical_off function

    mov ebx, buffer                 ;base address pointer to buffer
    mov ecx, 4                      ;counter total bytes to get of kb_input

get_kb_input:
    call read                       ;call read function

    mov al, byte[kb_input]          ;move single keypress into al

    cmp al, 30h                     ;cmp ASCII 0 to al
    jb invalid_kb_input             ;jmp if below

    cmp al, 39h                     ;cmp ASCII 9 to al
    ja invalid_kb_input             ;jmp if above

    mov byte[ebx], al               ;store valid byte to EBX pointer

    add ebx, 1                      ;advance pointer 1b to next kb_input

    call write                      ;call write function

    jmp next_byte                   ;jmp next_byte

invalid_kb_input:
    add ecx, 1                      ;compensation what loop takes away

next_byte:
    mov byte[kb_input], 0           ;mov 0 into byte of kb_input
    loop get_kb_input               ;loop get_kb_input

    call canonical_on               ;call canonical_on function

    call new_line                   ;call new_line function

display_buffer_message:
    mov ecx, display_buffer         ;mov display_buffer to ECX
    mov edx, display_bufferLEN      ;mov LEN to EDX
    call write_message              ;call write_message function

display_buffer_data:
    mov ecx, buffer                 ;mov buffer to ECX
    mov edx, bufferLEN              ;mov LEN to EDX
    call write_message              ;call write_message function

    call new_line                   ;call new_line function

    call exit                       ;call exit function