Upload dragon ship custom spritesheets dynamically

Overworld/custom_gfx.asm

@@ -12,6 +12,7 @@ CheckForChangeGraphicsNormalLoadBoat:
     LDA $8A : CMP.b #$30 : BNE .boat_area
     PHB : PHK : PLB
     JSR ApplyGraphics1
+    JSR ApplyGraphics2
     PLB
     RTL
   .boat_area
@@ -56,6 +57,26 @@ ApplyGraphics1:
   incbin gfx/boat.bin
 }
 
+ApplyGraphics2:
+{
+  REP #$20               ; A = 16, XY = 8
+  LDX #$80 : STX $2115   ; Set the video port register every time we write it increase by 1
+  LDA #$5000 : STA $2116 ; Destination of the DMA $7800 in vram <- this need to be divided by 2
+  LDA #$1801 : STA $4300 ; DMA Transfer Mode and destination register 
+                                ; "001 => 2 registers write once (2 bytes: p, p+1)"
+  LDA.w #AdditionalBitmap : STA $4302     ; Source address where you want gfx from ROM
+  LDX.b #AdditionalBitmap>>16 : STX $4304
+  LDA   #$2000 : STA $4305          ; size of the transfer 4 sheets of $800 each
+  LDX   #$01 : STX $420B            ; Do the DMA 
+
+  SEP #$30
+
+  RTS
+
+  AdditionalBitmap:
+  incbin gfx/boat2.bin
+}
+
 ; ==============================================================================
 
 ApplyKorokSpriteSheets: