Add sound support

*Update readme
* Add hardware.inc as submodule

.gitignore

@@ -1,2 +1,3 @@
 *.o
 *.bin
+.vscode

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "hardware.inc"]
+	path = hardware.inc
+	url = https://github.com/gbdev/hardware.inc

Makefile

@@ -19,7 +19,7 @@ $(TARGET).bin: $(TARGET).o
 	$(RGBLINK) ${LINKFLAGS} -o $@ $^
 
 $(TARGET).o: $(SRC_DIR)/bootrom.asm
-	$(RGBASM) $(ASMFLAGS) -o $@ $^
+	$(RGBASM) $(ASMFLAGS) -i hardware.inc -o $@ $^
 
 .PHONY: clean
 clean:

README.md

@@ -4,32 +4,25 @@ A custom copyright free Gameboy (DMG) bootrom Im making for my own GameBoy emula
 
 ![image](https://user-images.githubusercontent.com/25867720/141697694-a24ea751-7c32-41bd-8d90-e36b9b8bb0c9.png)
 
-## Current state
-
-This project is currently WIP.
-
-This my first time writing an actual software in any kind of assembly so any tips and suggestions are welcomed!
-
-I tried to stracture the file in a sensible way but the code is still a bit messy.
-
-### Features
+## Features
 
 * Custom boot screen made by me
-* Scrolling with a twist
+* Scrolling
+* Sound
 
 ### Future plans
 
-* Cycle accuracy with the original bootrom
-* Sound
+* Opcode accuracy with the original bootrom
 
 ## Building
 
 * Make sure `make` and `rgbds` are installed. (On Windows both can be installed with chocolatey package manager)
-* execute `make`
+* run `make`
 
-### Platforms
+### Build platforms
 
-Built and tested on Windows 10 and Linux (Ubuntu 20.4)
+* Windows 10
+* Linux (Ubuntu 20.04)
 
 ## Tools
 
@@ -42,5 +35,4 @@ The gbdev community and especially the awsome gbdev [repo](https://github.com/gb
 and especially
 * [rgbds](https://github.com/gbdev/rgbds) - for the awsome development toolchain
 * [The pandocs](https://gbdev.io/pandocs/) - for the awsome docs
-* [Harry Mulders Gameboy dev tools](http://www.devrs.com/gb/hmgd/intro.html) - for the awsome tile design tools.
-
+* [Harry Mulders Gameboy dev tools](http://www.devrs.com/gb/hmgd/intro.html) - for the awsome tile design tools.

src/bootrom.asm

@@ -1,3 +1,8 @@
+INCLUDE "hardware.inc"
+
+DEF WAIT_LEN equ 2
+DEF SCROLL_LEN equ 10
+
 SECTION "main", ROM0[$0]
 
 Main::
@@ -10,14 +15,6 @@ Main::
     ld bc, $2000    ; vram size        
     call Memset    ; init vram
 
-    ld hl, $C000    ; ram address
-    ld bc, $2000    ; ram size
-    call Memset    ; init ram
- 
-    ld hl, $FE00    ; OAM adress
-    ld bc, $00A0    ; OAM size
-    call Memset    ; init oam
-
     ld hl, $9A43
     ld de, $9A63
     ld b, 29
@@ -35,22 +32,38 @@ Main::
     ld a, %10010001 ; Turn lcd and BG on
     ld [$ff40], a
 
-    .scrollLoop
-        ld b, $F       ; wait time
-        call Wait
-        ld a, [$FF42]
-        inc a
-        ld [$FF42], a
-        cp a, $50
-        jr nz, .scrollLoop
-    
-    ld c, $5        ; counter for the wait loop, determines the length of the wait
-    .waitLoop
-        ld b, $FF
-        call Wait
-        dec c
-        jr nz, .waitLoop
-    
+.scrollLoop
+    ld b, SCROLL_LEN    ; wait time
+    call Wait
+    ld a, [$FF42]
+    inc a
+    ld [$FF42], a
+    cp a, $50
+    jr nz, .scrollLoop
+     
+    ; start sound
+    ld a, %01110111 ; left and right max volume
+    ld [rNR50], a
+    ld a, %10001    ; turn channel 1 on
+    ld [rNR51], a
+    ld a, $80       ; enable sound
+    ld [rNR52], a
+    ld a, %10000000 ; normal wave duty and max len
+    ld [rNR11], a
+    ld a, $F1       ; 0xF volume, volume envelope len 1
+    ld [rNR12], a
+    ld a, $FF       ; 0xFF low freq 
+    ld [rNR13], a
+    ld a, %11000110 ; start sound, terminated by len, 0x6 high freq
+    ld [rNR14], a
+
+    ld c, WAIT_LEN  ; counter for the wait loop, determines the length of the wait
+.waitLoop
+    ld b, $FF   ; max wait for Wait proc, 
+    call Wait
+    dec c
+    jr nz, .waitLoop
+
     jp FinishBoot
 
 ; mut b - wait length
@@ -81,8 +94,8 @@ SetTilemap:
     pop hl
     cp a, b
     jr nz, SetTilemap
-    .return
-        ret
+.return
+    ret
 
 ; mut hl - dst (address to set)
 ; mut bc - len (non zero length)
@@ -100,9 +113,9 @@ Memset:
 
     ld a, d     ; loads a
     ret
-    .continue:
-        ld a, d ; loads a
-        jr Memset
+.continue:
+    ld a, d ; loads a
+    jr Memset
 
 ; mut hl - dst (address to copy to)
 ; mut bc - src (adress to copy from)
@@ -130,24 +143,24 @@ DecodeLogoToVram:
     ld d, a
     ld e, a
     ld c, 2
-    .decodeNibleToByte
-        ld b, 4
-        .mulBit
-            rl d
-            rla
-            rl e
-            rla
-            dec b
-            jr nz, .mulBit
-        ld b, 2
-        .loadValueToVram
-            ldi [hl], a
-            ld [hl], 0      ; redunant the vram is already zeroed
-            inc hl
-            dec b
-            jr nz, .loadValueToVram
-        dec c
-        jr nz, .decodeNibleToByte
+.decodeNibleToByte
+    ld b, 4
+.mulBit
+    rl d
+    rla
+    rl e
+    rla
+    dec b
+    jr nz, .mulBit
+    ld b, 2
+.loadValueToVram
+    ldi [hl], a
+    ld [hl], 0      ; redunant the vram is already zeroed
+    inc hl
+    dec b
+    jr nz, .loadValueToVram
+    dec c
+    jr nz, .decodeNibleToByte
     pop bc
     pop de
     inc bc