easy6502_beams-generated.asm

StoreGun:
 ; Line order data starting at $20
 LDA #$00   ; Gun 1 Blue Laser Upper Row
 STA $20
 LDA #$60   ; 2 red
 STA $21
 LDA #$68   ; 3 green
 STA $22
 LDA #$00   ; 4 blue
 STA $23
 LDA #$00   ; Gun 1 Blue Laser Upper Row
 STA $24
 LDA #$60   ; 2 red
 STA $25
 LDA #$68   ; 3 green
 STA $26
 LDA #$68   ; 4 green
 STA $27
 LDA #$00   ; Gun 1 Blue Laser Upper Row
 STA $28
 LDA #$60   ; 2 red
 STA $29
 LDA #$68   ; 3 green
 STA $2a
 LDA #$00   ; 4 blue
 STA $2b
 LDA #$00   ; Gun 1 Blue Laser Upper Row
 STA $2c
 LDA #$60   ; 2 red
 STA $2d
 LDA #$68   ; 3 green
 STA $2e
 LDA #$60   ; 4 red
 STA $2f
 LDA #$08   ; Gun 1 Blue Laser Bottom Row
 STA $30
 LDA #$18   ; 2 red bottom
 STA $31
 LDA #$70   ; 3 green bottom
 STA $32
 LDA #$18   ; 4 red bottom
 STA $33
 LDA #$10   ; Gun 1-4 Body Rows
 STA $34
 STA $35
 STA $36
 STA $37
 LDA #$10   ; Gun 1-4 Body Rows
 STA $38
 STA $39
 STA $3a
 STA $3b
 LDA #$10   ; Gun 1-4 Body Rows
 STA $3c
 STA $3d
 STA $3e
 STA $3f
 LDA #$ff   ; Done
 STA $40

 ; Blue Laser Upper Rows ($00-$07)
 LDA #$06
 STA $01
 LDA #$0e
 STA $02
 LDA #$03
 STA $03
 LDA #$01
 STA $04
 LDA #$03
 STA $05
 LDA #$0e
 STA $06
 LDA #$06
 STA $07

 ; Blue Laser Bottom Row ($08-$10)
 LDA #$06
 STA $0a
 LDA #$0e
 STA $0b
 LDA #$01
 STA $0c
 LDA #$0e
 STA $0d
 LDA #$06
 STA $0e

 ; Red Laser Upper Rows ($60-$67)
 LDA #$02
 STA $61
 LDA #$08
 STA $62
 LDA #$07
 STA $63
 LDA #$01
 STA $64
 LDA #$07
 STA $65
 LDA #$08
 STA $66
 LDA #$02
 STA $67

 ; Red Laser Bottom Row ($18-$1f)
 LDA #$02
 STA $1a
 LDA #$08
 STA $1b
 LDA #$01
 STA $1c
 LDA #$08
 STA $1d
 LDA #$02
 STA $1e

 ; Green Laser Upper Rows ($68-$6f)
 LDA #$09
 STA $69
 LDA #$05
 STA $6a
 LDA #$0d
 STA $6b
 LDA #$01
 STA $6c
 LDA #$0d
 STA $6d
 LDA #$05
 STA $6e
 LDA #$09
 STA $6f

 ; Green Laser Upper Rows ($70-$77)
 LDA #$09
 STA $72
 LDA #$05
 STA $73
 LDA #$01
 STA $74
 LDA #$05
 STA $75
 LDA #$09
 STA $76

 ; Gun Body Row ($11-$17)
 LDA #$0b
 STA $11
 LDA #$0b
 STA $12
 LDA #$0c
 STA $13
 LDA #$0c
 STA $14
 LDA #$0f
 STA $15
 LDA #$0f
 STA $16
 LDA #$0c
 STA $17

DrawGun:
              ; A: Color
 LDX #$00     ; X: Init memory pos reader counter.
 LDY #$00     ; Y: Init screen pos writer counter.
 LDA #$01     ; | Init address $50: Line order counter.
 STA $50      ; |
              ;        Address $51: Backup space for Y
              ; | Init address $52: Line progress counter
 
DrawGunLoop:
 LDA $00,X    ; Read color from address $00+X
 STA $0200,Y  ; Store this color to address $0200+Y
 INX
 INC $52
 LDA $52
 CMP #$09     ; Check if line is done
 BEQ AddLine
 INY
 JMP DrawGunLoop

AddLine: 
 LDA #$00    ; \ Reset line progress counter
 STA $52     ; / 
 TYA         ; \ Backup Y (screen pos counter) into $51
 STA $51     ; / 
 LDY $50     ; Load into Y Line Order Counter ($50)
 
 ; Re-set memory read position X by reading the line order data starting at $20
 LDA $0020,Y ; Y now being the line order count
 CMP #$ff
 BEQ Exit
 TAX         ; Give the resulting reset point to X
 INY         ; Increment line order counter
 STY $50     ; Store it back into $50
 LDY $51     ; Recover backup of Y to Y (screen pos counter)
 JMP DrawGunLoop

Exit:
 BRK