0x10c

; Acquire device numbers
hwn I
:map_devices
    hwq i
    ife b, 0x7349
        ife a, 0xf615
            set [monitor], i
    ife b, 0x30cf
        ife a, 0x7406
            set [keyboard], i
    sub i, 1
    ifn i, 0
    set pc, map_devices

; Map monitor video ram
set a, 0x0
set b, [moni_ram_start]
hwi [monitor]

; Draw intro
set x, msg_start
set y, [moni_ram_start]
set z, 0x1e0
jsr drawstr

; Keyboard loop
set a, 0x1
set i, [cmd_buf] ; Command buffer index
set j, [moni_ram_start] ; Video RAM index
add j, 0x20 ; Offset for welcome message
set [j], 0xf0fc ; Draw cursor at start

:loop
    hwi [keyboard]
    ife c, 0x0
        set pc, loop

    ife c, 0x10
        set pc, backspace
    ife c, 0x11
        set pc, linebreak

    set [i], c ; Write to command buffer

    set z, 0xf000 ; Formatting helper variable
    add z, c ; Format
    set [j], z ; Write to video RAM

    ; Update indexes
    add i, 0x1
    add j, 0x1

    set [j], 0xf0fc ; Draw cursor
    set pc, loop

:backspace
    ife j, [bs_limit]
        set pc, loop
    set [j], 0x0 ; Delete cursor at current location
    ; Decrement indexes
    sub i, 0x1
    sub j, 0x1
    set [j], 0xf0fc ; Draw cursor
    set [i], 0x0 ; Delete buffer token
    set pc, loop

:linebreak
    set [j], 0x0
    set x, j
    sub x, [moni_ram_start]
    :linebreakloop
        add j, 0x1
        add x, 0x1
        set [j], 0xf0fc
        mod x, 0x20
        ifn x, 0x0
            set pc, linebreakloop
    set a, [cmd_buf]
    set b, cmdstr_version
    jsr cmpstr
    ife z, 0x1
        jsr tell_version
    set [j], 0xf0fc
    set pc, loop

:tell_version
    set x, msg_version
    set y, j
    set z, 0x1e0
    jsr drawstr
    set pc, pop
; Functions
; Write string from X to Y using formatting Z (bbbbffff_)
:drawstr
    set push, a
    shl z, 0x7
    :drawstr_loop
    set a, [x]
    add a, z
    set [y], a
    add x, 0x1
    add y, 0x1
    ifn [x], 0x0
    set pc, drawstr_loop
    set a, pop
    set pc, pop

; If strings starting at X and Y are equal, set Z to 0x1, otherwise 0x0
:cmpstr
    set z, 0x1
    :cmpstr_loop
    ifn [x], [y]
        set pc, cmpstr_break
    add x, 0x1
    add y, 0x1
    ifn x, 0x0
        ifn y, 0x0
            set pc, cmpstr_loop
    set pc, pop
    :cmpstr_break
        set z, 0x0
        set pc, pop

; Data
:monitor dat 0x0
:moni_ram_start dat 0x1f40

:keyboard dat 0x0

:cmd_buf dat 0x1b58

:bs_limit dat 0x1F60

:msg_start dat "Welcome to Shizuku.", 0x0

:cmdstr_version dat "version", 0x0
:msg_version dat "Version 0.1 Alpha", 0x0