|00 @System     [ &vect $2 &pad $6 &r $2 &g $2 &b $2 ]
|10 @Console    [ &vect $2 &r $1 &pad $5 &w $1 ]
|20 @Screen     [ &vect $2 &w $2 &h $2 &auto  $1 &pad $1 &x $2 &y $2 &addr $2 &pixel $1 &sprite $1 ]
|80 @Controller [ &vect $2 &button $1 &key $1 ]

|0000
    @tint      $1 ( draw mode. 01=regular, 04=inverted )
    @dirty?    $1 ( screen needs redraw? )

    @rows     $2 ( height in characters )
    @cols     $2 ( width in characters )
    @cur-x    $2 ( cursor x: 0 <= cur-x < cols )
    @cur-y    $2 ( cursor y: 0 <= cur-y < rows )

|0100
    ( 80 cols x 24 rows )
    #0028 .rows STZ2
    #0050 .cols STZ2

    ( set screen height/width based on rows/cols )
    .rows LDZ2 #30 SFT2 .Screen/h DEO2
    .cols LDZ2 #30 SFT2 .Screen/w DEO2

    ( set colors )
    #0cf0 .System/r DEO2
    #0c88 .System/g DEO2
    #0c0f .System/b DEO2

    ( clear screen for initial draw )
    ;clear-screen JSR2

    ( set up interrupts )
    ;redraw .Screen/vect DEO2     ( set up screen )
    ;on-key .Controller/vect DEO2 ( set up keyboard )
    ;on-input .Console/vect DEO2  ( set up stdin )

    ( return )
    BRK

@clear-screen
    #01 .dirty? STZ
    ;screen STH2
    #0000 &yloop
        #0000 &xloop
            #20 STH2kr STA INC2r
            INC2 DUP2 .cols LDZ2 LTH2 ,&xloop JCN
        POP2
        INC2 DUP2 .rows LDZ2 LTH2 ,&yloop JCN
    POP2 POP2r
    JMP2r

@redraw
    #41 .tint STZ
    .dirty? LDZ #00 EQU ,&done JCN
    ;screen STH2
    #0000 DUP2 .Screen/y DEO2
    &yloop
        #0000 DUP2 .Screen/x DEO2
        &xloop
            STH2kr LDA ;draw-tile JSR2
            .Screen/x DEI2 #0008 ADD2 .Screen/x DEO2
            INC2 INC2r
            DUP2 .cols LDZ2 LTH2 ,&xloop JCN
        POP2
        .Screen/y DEI2 #0008 ADD2 .Screen/y DEO2
        INC2
        DUP2 .rows LDZ2 LTH2 ,&yloop JCN
    POP2 POP2r

    ;show-cursor JSR2
    #00 .dirty? STZ
    &done BRK

@hide-cursor
    .tint LDZ
    #41 .tint STZ
    ;draw-cursor JSR2
    .tint STZ JMP2r

@show-cursor
    .tint LDZ
    #44 .tint STZ
    ;draw-cursor JSR2
    .tint STZ JMP2r

@draw-cursor
    .cur-x LDZ2 #30 SFT2 .Screen/x DEO2
    .cur-y LDZ2 #30 SFT2 .Screen/y DEO2
    .cur-y LDZ2 .cols LDZ2 MUL2 .cur-x LDZ2 ADD2 ;screen ADD2 LDA
    ;draw-tile JMP2

@on-key ( -> )
    .Controller/key DEI ,&ok JCN BRK
    &ok ,alt? JSR ,on-alt-key JCN
        ,ctrl? JSR ,on-ctrl-key JCN
        .Controller/key DEI .Console/w DEO BRK

@ctrl? ( -> down? ) .Controller/button DEI #01 AND JMP2r
@alt?  ( -> down? ) .Controller/button DEI #02 AND JMP2r

( alt-XYZ emits ESC and then emits XYZ )
@on-alt-key ( -> )
    #1b .Console/w DEO
    ,ctrl? JSR ,on-ctrl-key JCN
    .Controller/key DEI .Console/w DEO BRK

( ctrl-$n emits: )
(   0 <= $n < @     ->   $n         )
(   @ <= $n < `     ->   $n #40 SUB )
(   ` <= $n <= #ff  ->   $n #60 SUB )
@on-ctrl-key ( -> )
    .Controller/key DEI
    DUP LIT "@ LTH ,&done JCN
    DUP LIT "` LTH ,&c1 JCN
    LIT "` SUB ,&done JMP
    &c1 LIT "@ SUB
    &done .Console/w DEO BRK

@on-input
    .Console/r DEI
    DUP ,&ok JCN POP BRK
    &ok #41 .tint STZ
    ;read JSR2 BRK

@read ( byte^ -> )
    DUP #07 EQU ;read-bel JCN2
    DUP #08 EQU ;read-bs JCN2
    DUP #09 EQU ;read-tab JCN2
    DUP #0a EQU ;read-nl JCN2
    DUP #0d EQU ;read-cr JCN2
    DUP #1b EQU ;read-esc JCN2
    DUP #7f EQU ;read-del JCN2
    ;read-printable JMP2

( TODO: we need line-editing! )
@read-bel POP JMP2r
@read-bs POP JMP2r ( POP ;scroll JMP2 )
@read-esc POP JMP2r
@read-del POP JMP2r

( @read-tab POP JMP2r )
@read-tab
    POP
    .cur-x LDZ2 NIP #07 AND #08 SUB
    &loop
    #20 DUP ;cursor-addr JSR2 STA
    ;draw-tile JSR2
    ;forward JSR2
    INC DUP ,&loop JCN
    POP JMP2r

@read-cr ( 0d -> )
    POP ;hide-cursor JSR2 #0000 .cur-x STZ2 JMP2r

@read-nl ( 0a -> )
    POP ;hide-cursor JSR2 ;down JMP2

@read-printable ( c -> )
    DUP ;cursor-addr JSR2 STA
    ;draw-tile JSR2
    ;forward JMP2

@forward ( -> )
    .cur-x LDZ2 INC2 DUP2 .cols LDZ2 LTH2 ,&ok JCN
    POP2 #0000 .cur-x STZ2 ;down JMP2
    &ok .cur-x STZ2
    ;show-cursor JMP2

@back ( -> )
    .cur-x LDZ2 #0000 GTH2 ,&continue JCN
    POP2 POP JMP2r
    &continue ( addr^ value* )
    ;hide-cursor JSR2
    .cur-x LDZ2 #0001 SUB2 .cur-x STZ2
    ;show-cursor JMP2

@down ( -> )
    .cur-y LDZ2 INC2 DUP2 .rows LDZ2 LTH2 ,&ok JCN
    POP2 ;scroll JMP2
    &ok .cur-y STZ2
    ;show-cursor JMP2

@scroll
    ;end-screen STH2
    ;screen .cols LDZ2 ADD2 STH2
    &loop
        STH2kr LDA #20 STH2kr STA
        STH2kr .cols LDZ2 SUB2 STA
        INC2r GTH2kr STHr ,&loop JCN
    POP2r POP2r
    #01 .dirty? STZ
    ;show-cursor JMP2

@cursor-addr ( -> addr* )
    .cur-y LDZ2 .cols LDZ2 MUL2
    .cur-x LDZ2 ADD2 ;screen ADD2
    JMP2r

( 0 <= c < 256 )
@draw-tile ( c^ -> )
    DUP #80 LTH
    ,draw-7bit JCN
    ,draw-8bit JMP

( 0 <= index < 128 )
@load-tile ( index^ -> )
    #00 SWP #30 SFT2
    ;ascii ADD2 .Screen/addr DEO2
    JMP2r

( 0 <= c < 128 )
@draw-7bit ( c^ -> )
    ;load-tile JSR2
    .tint LDZ .Screen/sprite DEO
    JMP2r

( 128 <= c < 256 )
@draw-8bit ( 8bit^ -> )
    #80 SUB ;load-tile JSR2
    .tint LDZ #05 EOR .Screen/sprite DEO
    JMP2r

( 128 1-bit 8x8 tiles for ASCII 7-bit characters )
@ascii
    ~chr/ascii.tal

( store characters for redraw, etc. )
@screen $0c80 ( 80 x 40 )
@end-screen

( store attributes for redraw, etc. )
@attrs $0c80 ( 80 x 40 )
@end-attrs