0x42c scrolling

SET PC, initialstate

; string definitions (currently using C-style strings)
:version dat "0x42c v.0.1 128K MEM READY", 0
:input dat "> ", 0

; commands
:reddit dat "reddit", 0
:date dat "date", 0
:clean dat "clear", 0
:vers dat "version", 0
:echo dat "echo", 0

; outputs
:redditoutput dat "Reddit, the frontpage of the internet.", 0
:dateoutput dat "00:00:00 UTC on 1 January 1970", 0
:unrecognized dat "Unrecognized command '", 0
:unrecognizedEnd dat "'.", 0


:initialstate
set [0x1335], 0x8000   ; vidmem
set [0x1337], 0x1338   ; input buffer

:main
set a, version
jsr printnl      ; printnl(version)

:inputready
set a, input
jsr print        ; printnl(input)

set pc, kbloop

:kbloop
ife [0x9000], 0   ; if there's no input...
   set pc, kbloop
ife [0x9000], 0xA ; enter
   jsr enteredcommand
ife [0x9000], 0x8 ; backspace
   jsr backspace

set a, [0x9000]
jsr printchar     ; printchar([0x9000])

set a, [0x1337]   ; 0x1337 is the pointer to my buffer string
set b, [0x9000]
jsr strcat        ; strcat([0x1337], [0x9000])
add [0x1337], 1

set [0x9000], 0

set pc, kbloop

:backspace
sub [0x1335], 1    ; video pointer

        sub [0x1337], 1    ; delete last char

        set a, [0x1337]
set [a], 0

        set a, 0
jsr printchar      ; printchar(0)
sub [0x1335], 1
set [0x9000], 0
set pc, kbloop

:reset
set [0x1337], 0x1338 ; reset pointer
set [0x1338], 0      ; reset string
set [0x9000], 0      ; reset keyboard
set [0x1336], 0      ; reset command recognized
set pc, pop

:enteredcommand
set a, echo
set b, 0x1338
jsr startswith        ; startswith(echo, 0x1338)
ife y, 1
   jsr echof

set a, reddit
set b, 0x1338
jsr strcmp             ; strcmp(reddit, 0x1338)
ife y, 1
   jsr redditf

set a, date
set b, 0x1338
jsr strcmp            ; strcmp(date, 0x1338)
ife y, 1
jsr datef

set a, clean
set b, 0x1338
jsr strcmp            ; strcmp(date, 0x1338)
ife y, 1
jsr cleanf

set a, vers
set b, 0x1338
jsr strcmp            ; strcmp(vers, 0x1338)
ife y, 1
jsr versionf

ifn a, 1
jsr unrecognizedf

:enterdone
   jsr reset
   set pc, inputready


:echof
jsr newline
set a, echo
jsr strlen
add a, 1 ; +1 to strlen,
                        ; for the space

set b, 0x1338
add b, a ; start at `strlen'
set a, b ; string pointer
jsr printnl

set a, 1
set pc, enterdone

:cleanf
jsr clearScreen
set [0x1335], 0x8000
set a, 1
set pc, enterdone

:clearScreen
    set i, sp
    set sp, 0x8200
        :clearScreen_loop
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   set push, 0
   ifg 0x8000, sp
       set pc, clearScreen_done
   set pc, clearScreen_loop

        :clearScreen_done
   set sp, i
   set pc, pop

:versionf
jsr newline
jsr reset
set a, 1              ; return 1
set pc, main

:unrecognizedf
jsr newline
set a, unrecognized
jsr print
        set a, 0x1338
        jsr print
        set a, unrecognizedEnd
        jsr printnl

set a, 1               ; return 1
set pc, enterdone

:redditf
        set x, 1337
jsr printnl
set a, redditoutput
jsr printnl
set a, 1               ; return 1
set pc, enterdone

:datef
jsr printnl
set a, dateoutput
jsr printnl
set a, 1               ; return 1
set pc, enterdone


;  === STANDARD FUNCTIONS OVER HERE ===

:startswith
set y, 0

ife [a], 0
   set pc, startswith_end_success

ife [a], [b]
   jsr checkzero

        ifn [a], [b]
            set pc, pop

ife y, 1
   set pc, pop

add a, 1
add b, 1
set pc, startswith

:startswith_end_success
set y, 1
set pc, pop

:strlen
set y, 0

:strlen_begin
ife [a], 0
set pc, strlen_end

add y, 1
add a, 1
set pc, strlen_begin

:strlen_end
set a, y
set pc, pop


:strcmp
set y, 0

ife [a], [b]
            jsr checkzero

ife y, 1
   set pc, pop

ifn [a], [b]
   set pc, pop

add a, 1
add b, 1
set pc, strcmp

:checkzero
ife [a], 0
   set y, 1
set pc, pop

:strcat
set [a], b
add a, 1
        add b, 1
set [a], 0
set pc, pop


:printnl   ; shortcut
jsr print
jsr newline
set pc, pop

:print
set i, a
:doprint
   ifg [0x1335], 0x81ff ; end of vidmem
       jsr scroll
   ife [i], 0
       set pc, pop
   set a, [i]
   jsr printchar
   add i, 1
   set pc, doprint

:printchar
set b, [0x1335]
bor a, 0xf000 ; color :D
set [b], a
add [0x1335], 1
set pc, pop

:newline
set i, [0x1335]
mod i, 32 ; width
set z, 32
sub z, i
add [0x1335], z
set pc, pop


:scroll
    set a, 0x8000
    set b, 0x8020
    :scroll_loop
        set [a], [b]
        add a, 1
        add b, 1
        ifg b, 0x81ff
            set pc, scroll_clear_ll
        set pc, scroll_loop

        :scroll_clear_ll
        set [a], 0
        add a, 1
        ifg a, 0x81ff
            set pc, scroll_end
        set pc, scroll_clear_ll

    :scroll_end
        set [0x1335], 0x81e0
        set pc, pop


:end set pc, end