CPU 8086
ORG 0x9e00

jmp start

;Calls
%include "BYTE2HEX.INC"
%include "CMPSTR.INC"
%include "PRINTNL.INC"
%include "PRINTCH.INC"
%include "PRINTSTR.INC"
%include "PRINTLN.INC"
%include "READCH.INC"
%include "READSTR.INC"
%include "READLN.INC"

;Commands
%include "ECHO.INC"
%include "HELLO.INC"
%include "HELP.INC"
%include "KEYCODE.INC"

start:

;Get the terminal width
mov ah, 0xf
int 0x10
mov [cpl], ah

;Print a welcome message
mov si, welcome
call println

loop:

;Print a prompt
mov si, prompt
call printstr

;Read a command
mov di, buffer
mov al, 0xff
call readln

;Identify and execute the command
exec:
;Check for no command
cmp byte [buffer], 0x0
je loop
.echo:
;Check
mov si, buffer
mov di, cmd.echo
call cmpstr
jnc .hello
;Execute
call echo
jmp loop
.hello:
;Check
mov si, buffer
mov di, cmd.hello
call cmpstr
jnc .help
;Execute
call hello
jmp loop
.help:
;Check
mov si, buffer
mov di, cmd.help
call cmpstr
jnc .keycode
;Execute
call help
jmp loop
.keycode:
;Check
mov si, buffer
mov di, cmd.keycode
call cmpstr
jnc .error
;Execute
call keycode
jmp loop
.error:
mov si, error
call println
jmp loop

cpl db 0x0

welcome db 0xd, 0xa, "Welcome to EttinOS!", 0xd, 0xa, 0x0

prompt db "> ", 0x0

cmd:
.echo    db "echo", 0x0
.hello   db "hello", 0x0
.help    db "help", 0x0
.keycode db "keycode", 0x0

error db "Unknown command", 0x0

buffer times 0xff db 0