Make the SGB boot ROMs closer in timing to the original ones, fixed #602

BootROMs/sgb_boot.asm

@@ -119,6 +119,19 @@ Start:
     ld a, $30
     ld [c], a
     
+    ; Wait 4 frames
+    ld e, 4
+    ld a, 1
+    ldh [rIE], a
+    xor a
+.waitLoop
+    ldh [rIF], a
+    halt
+    nop
+    dec e
+    jr nz, .waitLoop
+    ldh [rIE], a
+    
     ; Update command
     ldh a, [_HRAM]
     add 2
@@ -198,16 +211,6 @@ DoubleBitsAndWriteRow:
     inc hl
     ret
 
-WaitFrame:
-    push hl
-    ld hl, $FF0F
-    res 0, [hl]
-.wait
-    bit 0, [hl]
-    jr z, .wait
-    pop hl
-    ret
-
 TrademarkSymbol:
 db $3c,$42,$b9,$a5,$b9,$a5,$42,$3c
 

Makefile

@@ -629,7 +629,7 @@ $(BIN)/BootROMs/sgb2_boot: BootROMs/sgb_boot.asm
 
 $(BIN)/BootROMs/%.bin: BootROMs/%.asm $(OBJ)/BootROMs/SameBoyLogo.pb12
 	-@$(MKDIR) -p $(dir $@)
-	$(RGBASM) -i $(OBJ)/BootROMs/ -i BootROMs/ -o $@.tmp $<
+	$(RGBASM) -H -i $(OBJ)/BootROMs/ -i BootROMs/ -o $@.tmp $<
 	$(RGBLINK) -o $@.tmp2 $@.tmp
 	dd if=$@.tmp2 of=$@ count=1 bs=$(if $(findstring cgb,$@)$(findstring agb,$@),2304,256) 2> $(NULL)
 	@rm $@.tmp $@.tmp2