movement

ass1/bonus-snake.asm

@@ -6,10 +6,15 @@
 .
 . keyboard settings: 
 . Address: 0x00C000
+.
+. frequency: 4000
 
 SNAKE   START   0
 
-FIRST   JSUB    RENDER
+FIRST   CLEAR   A
+LOOP    JSUB    RENDER
+
+        JSUB    WAIT
 
         .if (food was eaten) temp = snake[LEN - 1], generate new food:
 
@@ -18,47 +23,62 @@ FIRST   JSUB    RENDER
 
         .if (eaten) LEN++, snake[LEN - 1] = temp    
 
-        LDA     @KEY_IN
-        COMP    #0x41           .A
-        JEQ     LEFT
+        CLEAR   A
+        LDCH    @KEY_IN
+
+L10     COMP    #0x41           .A
+        JEQ     L3
         COMP    #0x57           .W
-        JEQ     UP
+        JEQ     L4
         COMP    #0x44           .D
-        JEQ     RIGHT
+        JEQ     L5
         COMP    #0x53           .S
-        JEQ     DOWN
+        JEQ     L6
 
-L3      RMO     A, X            .make horizontal move
-        LDA     @SNAKEX
-        ADDR    X, A
+        LDCH    DIREC
+        J       L10
+
+L3      STCH    DIREC
+        LDA     @SNAKEX         .move left
+        SUB     #1
         STA     @SNAKEX
-        J       L5
+        J       L7
 
-L4      RMO     A, X            .make vertical move
-        LDA     @SNAKEY
-        ADDR    X, A
+L4      STCH    DIREC
+        LDA     @SNAKEY         .move up
+        SUB     #1       
+        STA     @SNAKEY
+        J       L7
+
+L5      STCH    DIREC
+        LDA     @SNAKEX         .move right
+        ADD     #1        
+        STA     @SNAKEX
+        J       L7
+
+L6      STCH    DIREC
+        LDA     @SNAKEY         .move down
+        ADD     #1        
         STA     @SNAKEY
 
-L5      .check bounds
+L7      .check bounds
         .for (pos : snakex/y) assert x/y >= 0 && x/y <= 15
 
-        J       FIRST
+        JSUB    RENDER
+        J       LOOP
 
 HALT    J       HALT  
 
-.store direction
-LEFT    LDA     #-1
-        STA     DIREC
-        J       L3
-UP      LDA     #-0x10
-        STA     DIREC
-        J       L4
-RIGHT   LDA     #1
-        STA     DIREC
-        J       L3
-DOWN    LDA     #0x10
-        STA     DIREC
-        J       L4
+.waits some time before reading input so it doesnt feel laggy
+.no arguements, no return
+.changes A, X
+WAIT    LDA     #0
+        LDX     #0xA0
+L8      ADD     #1
+        COMPR   A, X
+        JEQ     L9
+        J       L8
+L9      RSUB
 
 .draws the snake
 .no arguements, no return
@@ -138,7 +158,7 @@ POP     LDA     ST_PTR
         LDA     @ST_PTR
         RSUB
 
-LEN     WORD    0               .snake length
+LEN     WORD    1               .snake length
 SCREEN  WORD    X'00A000'       .screen pointer
 KEY_IN  WORD    X'00C000'       .input pointer
 ST_PTR  WORD    X'000200'       .stack pointer, 2kB of space