added snake

ass1/bonus-snake.asm

@@ -0,0 +1,102 @@
+MOJPRG  START   0
+
+FIRST   LDS     #255
+        LDA     G_SCRN
+        STA     @CURSCR
+        STA     @SVEC
+LOOP    JSUB    DRAW
+        ADD     #4
+        STA     @SVEC
+        J       LOOP
+
+HALT    J       HALT  
+
+DRAW    JSUB    PUSH
+        RMO     T, A
+        JSUB    PUSH
+        RMO     S, A
+        JSUB    PUSH   
+
+        LDA     #0      .COUNTER      
+        LDT     @OFFSET
+STRT   COMP    @LEN
+        JEQ     END
+
+        JSUB    PUSH
+        LDA     SVEC
+        ADD     @OFFSET
+        STA     ADDR
+        LDA     @ADDR
+        STA     @BASEY
+
+        CLEAR A
+        
+LOOP1   COMP    FOUR
+        JEQ     LEND
+        LDS     @BASE
+        MUL     #64
+        ADDR    A, S
+        DIV     #64
+        STS     @BASEY
+        JSUB    PUSH
+        CLEAR   A
+
+LOOP2   COMP    FOUR
+        JEQ     LEND2
+        LDS     @BASEY
+        ADDR    A, S
+        STS     @CUR
+
+        LDS     #255
+        STS     @CUR
+
+        ADD     #1
+        J       LOOP2 
+
+LEND2     JSUB    POP
+        ADD     #1
+        J       LOOP1      
+
+LEND    JSUB    POP
+        ADD     #1
+        JSUB    PUSH
+        LDA     #3
+        ADDR    A, T
+        JSUB    POP
+        J       STRT
+
+END     JSUB    POP
+        RMO     A, T
+        JSUB    POP
+        RMO     A, S
+        JSUB    POP
+        RSUB
+        
+
+PUSH    STA     @S_PTR
+        LDA     S_PTR
+        ADD     #3
+        STA     S_PTR
+        RSUB
+
+POP     LDA     S_PTR
+        SUB     #3
+        STA     S_PTR
+        LDA     @S_PTR
+        RSUB
+
+FOUR    WORD    X'000004'
+ADDR    WORD    X'000000'
+CUR     WORD    X'000000'
+BASE    WORD    X'000000'
+BASEY   WORD    X'000000'
+LEN     WORD    X'000000'
+G_SCRN  WORD    X'00A000'
+CURSCR  WORD    X'000000'
+KEY_IN  WORD    X'00C000'
+S_PTR   WORD    X'000100'
+SVEC    WORD    X'001000'
+SVECMV  WORD    X'003000'
+OFFSET  WORD    X'000000'
+
+        END FIRST