snake

@screen @ctrl
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 RET
right: INC RET
left:  DEC RET
down: LIT 10 ADD RET
up:   LIT 10 SUB RET
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