snake.tny

Vectors:
    @screen @ctrl

Main:
    LIT 74 LIT 0 STB
    LIT 73 LIT 1 STB
    LIT 72 LIT 2 STB
BRK 

screen: 
    FRM
    LIT 6 MOD LIT 0 NEQ LIT @end JCN
        CLS

    LIT @len LDA 
    move: 
        DEC DUP
        DEC LDB OVR STB
        DUP LIT 1 GTH LIT @move JCN
    POP

        LIT dir: 1 LIT 0 LDB
        OVR LIT 0 EQU LIT @up    JCR
        OVR LIT 1 EQU LIT @right JCR
        OVR LIT 2 EQU LIT @down  JCR
        OVR LIT 3 EQU LIT @left  JCR
        LIT 0 STB POP
        LIT len: 3 
        
    draw: 
        DEC DUP
        LDB LIT 1 SET
        DUP LIT 1 GTH LIT @draw JCN 
            POP
        LIT 0 LDB
        DUP GET LIT @game_over JCN
            LIT tar: 7a DUP LIT 1 SET
        OVR EQU LIT @hit JCR
        LIT 1 SET

    end: 
BRK

hit: 
    LIT @len LDA INC LIT @len STA RND LIT @tar STA 
JMPr

right: 
    INC 
JMPr

left:  
    DEC 
JMPr

down: 
    LIT 10 ADD 
JMPr

up:   
    LIT 10 SUB 
JMPr

ctrl: 
    KEY
    LIT @dir LDA
    OVR LIT 8 EQU LIT @right JCR
    OVR LIT 4 EQU LIT @left  JCR
    LIT 4 MOD LIT @dir STA POP
BRK

game_over: 
    LIT 0 LIT 0 STA 
BRK