From 1d18e8e92e6d25fcbb4cd39d61b6416be1b9200e Mon Sep 17 00:00:00 2001
From: Forest Belton <forest@homolo.gy>
Date: Wed, 29 Sep 2021 06:14:41 -0400
Subject: [PATCH] Restore GBSDK subdirectory

---
 gbsdk/LICENSE              |  21 +
 gbsdk/README.md            |  26 ++
 gbsdk/inc/sdk/assets.h     |  18 +
 gbsdk/inc/sdk/assets.inc   |   6 +
 gbsdk/inc/sdk/banking.h    |  13 +
 gbsdk/inc/sdk/hardware.h   | 494 ++++++++++++++++++++
 gbsdk/inc/sdk/hardware.inc | 913 +++++++++++++++++++++++++++++++++++++
 gbsdk/inc/sdk/joypad.h     |  20 +
 gbsdk/inc/sdk/oam.h        |  19 +
 gbsdk/inc/sdk/sgb.h        |  39 ++
 gbsdk/inc/sdk/video.h      |  40 ++
 gbsdk/rules.mk             | 169 +++++++
 gbsdk/src/banking.asm      |  25 +
 gbsdk/src/entry.asm        |  18 +
 gbsdk/src/joypad.asm       |  48 ++
 gbsdk/src/oam.asm          |  44 ++
 gbsdk/src/sgb.asm          |  44 ++
 gbsdk/src/video.asm        | 116 +++++
 gbsdk/tools/asmconvert.py  | 227 +++++++++
 gbsdk/tools/romspace.py    |  16 +
 20 files changed, 2316 insertions(+)
 create mode 100644 gbsdk/LICENSE
 create mode 100644 gbsdk/README.md
 create mode 100644 gbsdk/inc/sdk/assets.h
 create mode 100644 gbsdk/inc/sdk/assets.inc
 create mode 100644 gbsdk/inc/sdk/banking.h
 create mode 100644 gbsdk/inc/sdk/hardware.h
 create mode 100644 gbsdk/inc/sdk/hardware.inc
 create mode 100644 gbsdk/inc/sdk/joypad.h
 create mode 100644 gbsdk/inc/sdk/oam.h
 create mode 100644 gbsdk/inc/sdk/sgb.h
 create mode 100644 gbsdk/inc/sdk/video.h
 create mode 100644 gbsdk/rules.mk
 create mode 100644 gbsdk/src/banking.asm
 create mode 100644 gbsdk/src/entry.asm
 create mode 100644 gbsdk/src/joypad.asm
 create mode 100644 gbsdk/src/oam.asm
 create mode 100644 gbsdk/src/sgb.asm
 create mode 100644 gbsdk/src/video.asm
 create mode 100644 gbsdk/tools/asmconvert.py
 create mode 100644 gbsdk/tools/romspace.py

diff --git a/gbsdk/LICENSE b/gbsdk/LICENSE
new file mode 100644
index 0000000..731e7d7
--- /dev/null
+++ b/gbsdk/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 Daid
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/gbsdk/README.md b/gbsdk/README.md
new file mode 100644
index 0000000..c60a74e
--- /dev/null
+++ b/gbsdk/README.md
@@ -0,0 +1,26 @@
+# Gameboy Software Development Kit
+
+This is the Gameboy software development kit. For mixed assembly and C programming. Note that this isn't a mature project yet.
+
+If you want to do C programming for the Gameboy, https://github.com/gbdk-2020/gbdk-2020 is much more mature.
+
+If you want to do assembly programming for the Gameboy, https://rgbds.gbdev.io/ is the goto toolchain.
+
+# But... but...? Why this then?
+
+This project has a few goals:
+
+* Thin/no abstractions. GBDK-2020 is an oddball of low level functions, badly named functions and high level functions with horrible performance and side effects.
+* Mixing of C code with ASM code, without subjecting yourself to the asxxxx syntax.
+* A different linker. By using the rgbds linker instead of the SDCC linker, a bunch of features that exernal tools provide on gbdk-2020 are standard.
+
+# Usage
+
+To use this, you need to have installed:
+
+* sdcc (version 4.1.0)
+* rgbds (version 0.5.1)
+* python (version 3.6 or newer)
+* A strong will, and a bit of crazy.
+
+See https://github.com/daid/gbsdk-template for a ready to use template of a project setup.
diff --git a/gbsdk/inc/sdk/assets.h b/gbsdk/inc/sdk/assets.h
new file mode 100644
index 0000000..70f5d1e
--- /dev/null
+++ b/gbsdk/inc/sdk/assets.h
@@ -0,0 +1,18 @@
+#ifndef GBSDK_ASSETS_H
+#define GBSDK_ASSETS_H
+
+#include <stdint.h>
+
+#define EXTERN_ASSET(var_name) \
+    extern const uint8_t var_name[]; \
+    extern const uint8_t var_name ## _end[]
+
+#define ASSET(var_name, filename) \
+    void __ ## var_name ## __() __naked { \
+        __asm__("_" #var_name "::"); \
+        __asm__(".incbin \"_build/assets/" filename "\""); \
+        __asm__("_" #var_name "_end::"); \
+    } EXTERN_ASSET(var_name)
+
+
+#endif//GBSDK_ASSETS_H
diff --git a/gbsdk/inc/sdk/assets.inc b/gbsdk/inc/sdk/assets.inc
new file mode 100644
index 0000000..14ccf6e
--- /dev/null
+++ b/gbsdk/inc/sdk/assets.inc
@@ -0,0 +1,6 @@
+; Usage: asset label_name, "filename"
+MACRO asset
+\1::
+    INCBIN STRCAT("_build/assets/", \2)
+.end::
+ENDM
diff --git a/gbsdk/inc/sdk/banking.h b/gbsdk/inc/sdk/banking.h
new file mode 100644
index 0000000..0593e99
--- /dev/null
+++ b/gbsdk/inc/sdk/banking.h
@@ -0,0 +1,13 @@
+#ifndef GBSDK_BANKING_H
+#define GBSDK_BANKING_H
+
+#include <stdint.h>
+
+extern __sfr current_bank;
+
+inline void switch_bank(bank_nr) {
+    current_bank = bank_nr;
+    *((uint8_t*)0x2000) = bank_nr;
+}
+
+#endif//LIB_BANKING_H
diff --git a/gbsdk/inc/sdk/hardware.h b/gbsdk/inc/sdk/hardware.h
new file mode 100644
index 0000000..e611d3b
--- /dev/null
+++ b/gbsdk/inc/sdk/hardware.h
@@ -0,0 +1,494 @@
+#ifndef GBSDK_HARDWARE_H
+#define GBSDK_HARDWARE_H
+
+// Register for reading joy pad info. (R/W)
+static volatile __sfr __at(0x00) rP1;
+
+#define P1_5 0b00100000 // P15 out port, set to 0 to get buttons
+#define P1_4 0b00010000 // P14 out port, set to 0 to get dpad
+#define P1_3 0b00001000 // P13 in port
+#define P1_2 0b00000100 // P12 in port
+#define P1_1 0b00000010 // P11 in port
+#define P1_0 0b00000001 // P10 in port
+
+#define P1_GET_DPAD P1_5
+#define P1_GET_BTN  P1_4
+#define P1_GET_NONE (P1_4 | P1_5)
+
+// Serial Transfer Data (R/W)
+static volatile __sfr __at(0x01) rSB;
+
+// Serial I/O Control (R/W)
+static volatile __sfr __at(0x02) rSC;
+
+// Divider register (R/W)
+static volatile __sfr __at(0x04) rDIV;
+
+// Timer counter (R/W)
+static volatile __sfr __at(0x05) rTIMA;
+
+// Timer modulo (R/W)
+static volatile __sfr __at(0x06) rTMA;
+
+// Timer control (R/W)
+static volatile __sfr __at(0x07) rTAC;
+
+#define TAC_START 0b00000100
+#define TAC_STOP 0b00000000
+#define TAC_4KHZ 0b00000000
+#define TAC_16KHZ 0b00000011
+#define TAC_65KHZ 0b00000010
+#define TAC_262KHZ 0b00000001
+
+// Interrupt Flag (R/W)
+static volatile __sfr __at(0x0F) rIF;
+
+// AUD1SWEEP/NR10 ($FF10)
+// Sweep register (R/W)
+//
+// Bit 6-4 - Sweep Time
+// Bit 3   - Sweep Increase/Decrease
+//           0: Addition    (frequency increases???)
+//           1: Subtraction (frequency increases???)
+// Bit 2-0 - Number of sweep shift (# 0-7)
+// Sweep Time: (n*7.8ms)
+static volatile __sfr __at(0x10) rNR10;
+#define rAUD1SWEEP rNR10
+
+#define AUD1SWEEP_UP 0b00000000
+#define AUD1SWEEP_DOWN 0b00001000
+
+// AUD1LEN/NR11 ($FF11)
+// Sound length/Wave pattern duty (R/W)
+//
+// Bit 7-6 - Wave Pattern Duty (00:12.5% 01:25% 10:50% 11:75%)
+// Bit 5-0 - Sound length data (# 0-63)
+static volatile __sfr __at(0x11) rNR11;
+#define rAUD1LEN rNR11
+
+// AUD1ENV/NR12 ($FF12)
+// Envelope (R/W)
+//
+// Bit 7-4 - Initial value of envelope
+// Bit 3   - Envelope UP/DOWN
+//           0: Decrease
+//           1: Range of increase
+// Bit 2-0 - Number of envelope sweep (# 0-7)
+static volatile __sfr __at(0x12) rNR12;
+#define rAUD1ENV rNR12
+
+// AUD1LOW/NR13 ($FF13)
+// Frequency low byte (W)
+static volatile __sfr __at(0x13) rNR13;
+#define rAUD1LOW rNR13
+
+// AUD1HIGH/NR14 ($FF14)
+// Frequency high byte (W)
+//
+// Bit 7   - Initial (when set, sound restarts)
+// Bit 6   - Counter/consecutive selection
+// Bit 2-0 - Frequency's higher 3 bits
+static volatile __sfr __at(0x14) rNR14;
+#define rAUD1HIGH rNR14
+
+// AUD2LEN/NR21 ($FF16)
+// Sound Length; Wave Pattern Duty (R/W)
+//
+// see AUD1LEN for info
+static volatile __sfr __at(0x16) rNR21;
+#define rAUD2LEN rNR21
+
+// AUD2ENV/NR22 ($FF17)
+// Envelope (R/W)
+//
+// see AUD1ENV for info
+static volatile __sfr __at(0x17) rNR22;
+#define rAUD2ENV rNR22
+
+// AUD2LOW/NR23 ($FF18)
+// Frequency low byte (W)
+static volatile __sfr __at(0x18) rNR23;
+#define rAUD2LOW rNR23
+
+// AUD2HIGH/NR24 ($FF19)
+// Frequency high byte (W)
+//
+// see AUD1HIGH for info
+static volatile __sfr __at(0x19) rNR24;
+#define rAUD2HIGH rNR24
+
+// AUD3ENA/NR30 ($FF1A)
+// Sound on/off (R/W)
+//
+// Bit 7   - Sound ON/OFF (1=ON,0=OFF)
+static volatile __sfr __at(0x1A) rNR30;
+#define rAUD3ENA rNR30
+
+// AUD3LEN/NR31 ($FF1B)
+// Sound length (R/W)
+//
+// Bit 7-0 - Sound length
+static volatile __sfr __at(0x1B) rNR31;
+#define rAUD3LEN rNR31
+
+// AUD3LEVEL/NR32 ($FF1C)
+// Select output level
+//
+// Bit 6-5 - Select output level
+//           00: 0/1 (mute)
+//           01: 1/1
+//           10: 1/2
+//           11: 1/4
+static volatile __sfr __at(0x1C) rNR32;
+#define rAUD3LEVEL rNR32
+
+// AUD3LOW/NR33 ($FF1D)
+// Frequency low byte (W)
+//
+// see AUD1LOW for info
+static volatile __sfr __at(0x1D) rNR33;
+#define rAUD3LOW rNR33
+
+// AUD3HIGH/NR34 ($FF1E)
+// Frequency high byte (W)
+//
+// see AUD1HIGH for info
+static volatile __sfr __at(0x1E) rNR34;
+#define rAUD3HIGH rNR34
+
+// AUD4LEN/NR41 ($FF20)
+// Sound length (R/W)
+//
+// Bit 5-0 - Sound length data (# 0-63)
+static volatile __sfr __at(0x20) rNR41;
+#define rAUD4LEN rNR41
+
+// AUD4ENV/NR42 ($FF21)
+// Envelope (R/W)
+//
+// see AUD1ENV for info
+static volatile __sfr __at(0x21) rNR42;
+#define rAUD4ENV rNR42
+
+// AUD4POLY/NR43 ($FF22)
+// Polynomial counter (R/W)
+//
+// Bit 7-4 - Selection of the shift clock frequency of the (scf)
+//           polynomial counter (0000-1101)
+//           freq=drf*1/2^scf (not sure)
+// Bit 3 -   Selection of the polynomial counter's step
+//           0: 15 steps
+//           1: 7 steps
+// Bit 2-0 - Selection of the dividing ratio of frequencies (drf)
+//           000: f/4   001: f/8   010: f/16  011: f/24
+//           100: f/32  101: f/40  110: f/48  111: f/56  (f=4.194304 Mhz)
+static volatile __sfr __at(0x22) rNR43;
+#define rAUD4POLY rNR43
+
+// AUD4GO/NR44 ($FF23)
+//
+// Bit 7 -   Inital
+// Bit 6 -   Counter/consecutive selection
+static volatile __sfr __at(0x23) rNR44;
+#define rAUD4GO rNR44
+
+// AUDVOL/NR50 ($FF24)
+// Channel control / ON-OFF / Volume (R/W)
+//
+// Bit 7   - Vin->SO2 ON/OFF (Vin??)
+// Bit 6-4 - SO2 output level (volume) (# 0-7)
+// Bit 3   - Vin->SO1 ON/OFF (Vin??)
+// Bit 2-0 - SO1 output level (volume) (# 0-7)
+static volatile __sfr __at(0x24) rNR50;
+#define rAUDVOL rNR50
+
+#define AUDVOL_VIN_LEFT 0b10000000 // SO2
+#define AUDVOL_VIN_RIGHT 0b00001000 // SO1
+
+// AUDTERM/NR51 ($FF25)
+// Selection of Sound output terminal (R/W)
+//
+// Bit 7   - Output sound 4 to SO2 terminal
+// Bit 6   - Output sound 3 to SO2 terminal
+// Bit 5   - Output sound 2 to SO2 terminal
+// Bit 4   - Output sound 1 to SO2 terminal
+// Bit 3   - Output sound 4 to SO1 terminal
+// Bit 2   - Output sound 3 to SO1 terminal
+// Bit 1   - Output sound 2 to SO1 terminal
+// Bit 0   - Output sound 0 to SO1 terminal
+static volatile __sfr __at(0x25) rNR51;
+#define rAUDTERM rNR51
+
+// SO2
+#define AUDTERM_4_LEFT 0b10000000
+#define AUDTERM_3_LEFT 0b01000000
+#define AUDTERM_2_LEFT 0b00100000
+#define AUDTERM_1_LEFT 0b00010000
+// SO1
+#define AUDTERM_4_RIGHT 0b00001000
+#define AUDTERM_3_RIGHT 0b00000100
+#define AUDTERM_2_RIGHT 0b00000010
+#define AUDTERM_1_RIGHT 0b00000001
+
+// AUDENA/NR52 ($FF26)
+// Sound on/off (R/W)
+//
+// Bit 7   - All sound on/off (sets all audio regs to 0!)
+// Bit 3   - Sound 4 ON flag (read only)
+// Bit 2   - Sound 3 ON flag (read only)
+// Bit 1   - Sound 2 ON flag (read only)
+// Bit 0   - Sound 1 ON flag (read only)
+static volatile __sfr __at(0x26) rNR52;
+#define rAUDENA rNR52
+
+#define AUDENA_ON 0b10000000
+#define AUDENA_OFF 0b00000000 // sets all audio regs to 0!
+
+// LCDC ($FF40)
+// LCD Control (R/W)
+static volatile __sfr __at(0x40) rLCDC;
+
+#define LCDC_OFF 0b00000000 // LCD Control Operation
+#define LCDC_ON 0b10000000 // LCD Control Operation
+#define LCDC_WIN9800 0b00000000 // Window Tile Map Display Select
+#define LCDC_WIN9C00 0b01000000 // Window Tile Map Display Select
+#define LCDC_WINOFF 0b00000000 // Window Display
+#define LCDC_WINON 0b00100000 // Window Display
+#define LCDC_BG8800 0b00000000 // BG & Window Tile Data Select
+#define LCDC_BG8000 0b00010000 // BG & Window Tile Data Select
+#define LCDC_BG9800 0b00000000 // BG Tile Map Display Select
+#define LCDC_BG9C00 0b00001000 // BG Tile Map Display Select
+#define LCDC_OBJ8 0b00000000 // OBJ Construction
+#define LCDC_OBJ16 0b00000100 // OBJ Construction
+#define LCDC_OBJOFF 0b00000000 // OBJ Display
+#define LCDC_OBJON 0b00000010 // OBJ Display
+#define LCDC_BGOFF 0b00000000 // BG Display
+#define LCDC_BGON 0b00000001 // BG Display
+
+// STAT ($FF41)
+// LCDC Status   (R/W)
+static volatile __sfr __at(0x41) rSTAT;
+
+#define STAT_LYC 0b01000000 // LYC=LY Coincidence (Selectable)
+#define STAT_MODE10 0b00100000 // Mode 10
+#define STAT_MODE01 0b00010000 // Mode 01 (V-Blank)
+#define STAT_MODE00 0b00001000 // Mode 00 (H-Blank)
+#define STAT_LYCF 0b00000100 // Coincidence Flag
+#define STAT_HBL 0b00000000 // H-Blank
+#define STAT_VBL 0b00000001 // V-Blank
+#define STAT_OAM 0b00000010 // OAM-RAM is used by system
+#define STAT_LCD 0b00000011 // Both OAM and VRAM used by system
+#define STAT_BUSY 0b00000010 // When set, VRAM access is unsafe
+
+// SCY ($FF42)
+// Scroll Y (R/W)
+static volatile __sfr __at(0x42) rSCY;
+
+// SCX ($FF43)
+// Scroll X (R/W)
+static volatile __sfr __at(0x43) rSCX;
+
+// LY ($FF44)
+// LCDC Y-Coordinate (R)
+//
+// Values range from 0->153. 144->153 is the VBlank period.
+static volatile __sfr __at(0x44) rLY;
+
+// LYC ($FF45)
+// LY Compare (R/W)
+//
+// When LY==LYC, STATF_LYCF will be set in STAT
+static volatile __sfr __at(0x45) rLYC;
+
+// DMA ($FF46)
+// DMA Transfer and Start Address (W)
+static volatile __sfr __at(0x46) rDMA;
+
+// BGP ($FF47)
+// BG Palette Data (W)
+//
+// Bit 7-6 - Intensity for %11
+// Bit 5-4 - Intensity for %10
+// Bit 3-2 - Intensity for %01
+// Bit 1-0 - Intensity for %00
+static volatile __sfr __at(0x47) rBGP;
+
+// OBP0 ($FF48)
+// Object Palette 0 Data (W)
+//
+// See BGP for info
+static volatile __sfr __at(0x48) rOBP0;
+
+// OBP1 ($FF49)
+// Object Palette 1 Data (W)
+//
+// See BGP for info
+static volatile __sfr __at(0x49) rOBP1;
+
+// WY ($FF4A)
+// Window Y Position (R/W)
+//
+// 0 <= WY <= 143
+// When WY = 0, the window is displayed from the top edge of the LCD screen.
+static volatile __sfr __at(0x4A) rWY;
+
+// WX ($FF4B)
+// Window X Position (R/W)
+//
+// 7 <= WX <= 166
+// When WX = 7, the window is displayed from the left edge of the LCD screen.
+// Values of 0-6 and 166 are unreliable due to hardware bugs.
+static volatile __sfr __at(0x4B) rWX;
+
+
+#if CGB
+// SPEED ($FF4D)
+// Select CPU Speed (R/W)
+static volatile __sfr __at(0x4D) rKEY1;
+#define rSPD  rKEY1
+
+#define KEY1_DBLSPEED 0b10000000 // 0=Normal Speed, 1=Double Speed (R)
+#define KEY1_PREPARE 0b00000001 // 0=No, 1=Prepare (R/W)
+
+// VBK ($FF4F)
+// Select Video RAM Bank (R/W)
+//
+// Bit 0 - Bank Specification (0: Specify Bank 0; 1: Specify Bank 1)
+static volatile __sfr __at(0x4F) rVBK;
+
+// HDMA1 ($FF51)
+// High byte for Horizontal Blanking/General Purpose DMA source address (W)
+static volatile __sfr __at(0x51) rHDMA1;
+
+// HDMA2 ($FF52)
+// Low byte for Horizontal Blanking/General Purpose DMA source address (W)
+static volatile __sfr __at(0x52) rHDMA2;
+
+// HDMA3 ($FF53)
+// High byte for Horizontal Blanking/General Purpose DMA destination address (W)
+static volatile __sfr __at(0x53) rHDMA3;
+
+// HDMA4 ($FF54)
+// Low byte for Horizontal Blanking/General Purpose DMA destination address (W)
+static volatile __sfr __at(0x54) rHDMA4;
+
+// HDMA5 ($FF55)
+// Transfer length (in tiles minus 1)/mode/start for Horizontal Blanking, General Purpose DMA (R/W)
+static volatile __sfr __at(0x55) rHDMA5;
+
+#define HDMA5_MODE_GP 0b00000000 // General Purpose DMA (W)
+#define HDMA5_MODE_HBL 0b10000000 // HBlank DMA (W)
+
+// Once DMA has started, use HDMA5F_BUSY to check when the transfer is complete
+#define HDMA5_BUSY 0b10000000 // 0=Busy (DMA still in progress), 1=Transfer complete (R)
+
+// RP ($FF56)
+// Infrared Communications Port (R/W)
+static volatile __sfr __at(0x56) rRP;
+
+#define RP_ENREAD 0b11000000
+#define RP_DATAIN 0b00000010 // 0=Receiving IR Signal, 1=Normal
+#define RP_WRITE_HI 0b00000001
+#define RP_WRITE_LO 0b00000000
+
+// BCPS ($FF68)
+// Background Color Palette Specification (R/W)
+static volatile __sfr __at(0x68) rBCPS;
+#define BCPS_AUTOINC 0b10000000 // Auto Increment (0=Disabled, 1=Increment after Writing)
+
+// BCPD ($FF69)
+// Background Color Palette Data (R/W)
+static volatile __sfr __at(0x69) rBCPD;
+
+// OCPS ($FF6A)
+// Object Color Palette Specification (R/W)
+static volatile __sfr __at(0x6A) rOCPS;
+#define OCPS_AUTOINC 0b10000000 // Auto Increment (0=Disabled, 1=Increment after Writing)
+
+// OCPD ($FF6B)
+// Object Color Palette Data (R/W)
+static volatile __sfr __at(0x6B) rOCPD;
+
+// SMBK/SVBK ($FF70)
+// Select Main RAM Bank (R/W)
+//
+// Bit 2-0 - Bank Specification (0,1: Specify Bank 1; 2-7: Specify Banks 2-7)
+static volatile __sfr __at(0x70) rSVBK;
+#define rSMBK rSVBK
+
+// PCM12 ($FF76)
+// Sound channel 1&2 PCM amplitude (R)
+//
+// Bit 7-4 - Copy of sound channel 2's PCM amplitude
+// Bit 3-0 - Copy of sound channel 1's PCM amplitude
+static volatile __sfr __at(0x76) rPCM12;
+
+// PCM34 ($FF77)
+// Sound channel 3&4 PCM amplitude (R)
+//
+// Bit 7-4 - Copy of sound channel 4's PCM amplitude
+// Bit 3-0 - Copy of sound channel 3's PCM amplitude
+static volatile __sfr __at(0x77) rPCM34;
+
+#endif //CGB
+
+// IE ($FFFF)
+// Interrupt Enable (R/W)
+static volatile __sfr __at(0xFF) rIE;
+
+#define IE_HILO 0b00010000 // Transition from High to Low of Pin number P10-P13
+#define IE_SERIAL 0b00001000 // Serial I/O transfer end
+#define IE_TIMER 0b00000100 // Timer Overflow
+#define IE_LCDC 0b00000010 // LCDC (see STAT)
+#define IE_VBLANK 0b00000001 // V-Blank
+
+
+/***************************************************************************
+ *
+ * Flags common to multiple sound channels
+ *
+ ***************************************************************************/
+
+// Square wave duty cycle
+//
+// Can be used with AUD1LEN and AUD2LEN
+// See AUD1LEN for more info
+#define AUDLEN_DUTY_12_5 0b00000000 // 12.5%
+#define AUDLEN_DUTY_25 0b01000000 // 25%
+#define AUDLEN_DUTY_50 0b10000000 // 50%
+#define AUDLEN_DUTY_75 0b11000000 // 75%
+
+// Audio envelope flags
+//
+// Can be used with AUD1ENV, AUD2ENV, AUD4ENV
+// See AUD1ENV for more info
+#define AUDENV_UP 0b00001000
+#define AUDENV_DOWN 0b00000000
+
+// Audio trigger flags
+//
+// Can be used with AUD1HIGH, AUD2HIGH, AUD3HIGH
+// See AUD1HIGH for more info
+#define AUDHIGH_RESTART 0b10000000
+#define AUDHIGH_LENGTH_ON 0b01000000
+#define AUDHIGH_LENGTH_OFF 0b00000000
+
+// Shared bits between the OAM attributes and the CGB background attributes.
+#define ATTR_PRI     0b10000000
+#define ATTR_YFLIP   0b01000000
+#define ATTR_XFLIP   0b00100000
+#define ATTR_PAL0    0b00000000
+#define ATTR_PAL1    0b00010000
+#if CGB
+#define ATTR_BANK0   0b00000000
+#define ATTR_BANK1   0b00001000
+#define ATTR_PALMASK 0b00000111
+#endif
+
+
+// Defines for specific instructions
+#define HALT() __asm__("halt")
+#define DISABLE_INTERRUPTS() __asm__("di")
+#define ENABLE_INTERRUPTS() __asm__("ei")
+
+#endif
diff --git a/gbsdk/inc/sdk/hardware.inc b/gbsdk/inc/sdk/hardware.inc
new file mode 100644
index 0000000..d676af7
--- /dev/null
+++ b/gbsdk/inc/sdk/hardware.inc
@@ -0,0 +1,913 @@
+;*
+;* Gameboy Hardware definitions
+;*
+;* Based on Jones' hardware.inc
+;* And based on Carsten Sorensen's ideas.
+;*
+;* Rev 1.1 - 15-Jul-97 : Added define check
+;* Rev 1.2 - 18-Jul-97 : Added revision check macro
+;* Rev 1.3 - 19-Jul-97 : Modified for RGBASM V1.05
+;* Rev 1.4 - 27-Jul-97 : Modified for new subroutine prefixes
+;* Rev 1.5 - 15-Aug-97 : Added _HRAM, PAD, CART defines
+;*                     :  and Nintendo Logo
+;* Rev 1.6 - 30-Nov-97 : Added rDIV, rTIMA, rTMA, & rTAC
+;* Rev 1.7 - 31-Jan-98 : Added _SCRN0, _SCRN1
+;* Rev 1.8 - 15-Feb-98 : Added rSB, rSC
+;* Rev 1.9 - 16-Feb-98 : Converted I/O registers to $FFXX format
+;* Rev 2.0 -           : Added GBC registers
+;* Rev 2.1 -           : Added MBC5 & cart RAM enable/disable defines
+;* Rev 2.2 -           : Fixed NR42,NR43, & NR44 equates
+;* Rev 2.3 -           : Fixed incorrect _HRAM equate
+;* Rev 2.4 - 27-Apr-13 : Added some cart defines (AntonioND)
+;* Rev 2.5 - 03-May-15 : Fixed format (AntonioND)
+;* Rev 2.6 - 09-Apr-16 : Added GBC OAM and cart defines (AntonioND)
+;* Rev 2.7 - 19-Jan-19 : Added rPCMXX (ISSOtm)
+;* Rev 2.8 - 03-Feb-19 : Added audio registers flags (�lvaro Cuesta)
+;* Rev 2.9 - 28-Feb-20 : Added utility rP1 constants
+;* Rev 3.0 - 27-Aug-20 : Register ordering, byte-based sizes, OAM additions, general cleanup (Blitter Object)
+
+; If all of these are already defined, don't do it again.
+
+IF !DEF(HARDWARE_INC)
+HARDWARE_INC SET 1
+
+rev_Check_hardware_inc : MACRO
+;NOTE: REVISION NUMBER CHANGES MUST BE ADDED
+;TO SECOND PARAMETER IN FOLLOWING LINE.
+    IF  \1 > 3.0 ;PUT REVISION NUMBER HERE
+        WARN    "Version \1 or later of 'hardware.inc' is required."
+    ENDC
+ENDM
+
+_VRAM        EQU $8000 ; $8000->$9FFF
+_VRAM8000    EQU _VRAM
+_VRAM8800    EQU _VRAM+$800
+_VRAM9000    EQU _VRAM+$1000
+_SCRN0       EQU $9800 ; $9800->$9BFF
+_SCRN1       EQU $9C00 ; $9C00->$9FFF
+_SRAM        EQU $A000 ; $A000->$BFFF
+_RAM         EQU $C000 ; $C000->$CFFF / $C000->$DFFF
+_RAMBANK     EQU $D000 ; $D000->$DFFF
+_OAMRAM      EQU $FE00 ; $FE00->$FE9F
+_IO          EQU $FF00 ; $FF00->$FF7F,$FFFF
+_AUD3WAVERAM EQU $FF30 ; $FF30->$FF3F
+_HRAM        EQU $FF80 ; $FF80->$FFFE
+
+; *** MBC5 Equates ***
+
+rRAMG        EQU $0000 ; $0000->$1fff
+rROMB0       EQU $2000 ; $2000->$2fff
+rROMB1       EQU $3000 ; $3000->$3fff - If more than 256 ROM banks are present.
+rRAMB        EQU $4000 ; $4000->$5fff - Bit 3 enables rumble (if present)
+
+
+;***************************************************************************
+;*
+;* Custom registers
+;*
+;***************************************************************************
+
+; --
+; -- P1 ($FF00)
+; -- Register for reading joy pad info. (R/W)
+; --
+rP1 EQU $FF00
+
+P1F_5 EQU %00100000 ; P15 out port, set to 0 to get buttons
+P1F_4 EQU %00010000 ; P14 out port, set to 0 to get dpad
+P1F_3 EQU %00001000 ; P13 in port
+P1F_2 EQU %00000100 ; P12 in port
+P1F_1 EQU %00000010 ; P11 in port
+P1F_0 EQU %00000001 ; P10 in port
+
+P1F_GET_DPAD EQU P1F_5
+P1F_GET_BTN  EQU P1F_4
+P1F_GET_NONE EQU P1F_4 | P1F_5
+
+
+; --
+; -- SB ($FF01)
+; -- Serial Transfer Data (R/W)
+; --
+rSB EQU $FF01
+
+
+; --
+; -- SC ($FF02)
+; -- Serial I/O Control (R/W)
+; --
+rSC EQU $FF02
+
+
+; --
+; -- DIV ($FF04)
+; -- Divider register (R/W)
+; --
+rDIV EQU $FF04
+
+
+; --
+; -- TIMA ($FF05)
+; -- Timer counter (R/W)
+; --
+rTIMA EQU $FF05
+
+
+; --
+; -- TMA ($FF06)
+; -- Timer modulo (R/W)
+; --
+rTMA EQU $FF06
+
+
+; --
+; -- TAC ($FF07)
+; -- Timer control (R/W)
+; --
+rTAC EQU $FF07
+
+TACF_START  EQU %00000100
+TACF_STOP   EQU %00000000
+TACF_4KHZ   EQU %00000000
+TACF_16KHZ  EQU %00000011
+TACF_65KHZ  EQU %00000010
+TACF_262KHZ EQU %00000001
+
+
+; --
+; -- IF ($FF0F)
+; -- Interrupt Flag (R/W)
+; --
+rIF EQU $FF0F
+
+
+; --
+; -- AUD1SWEEP/NR10 ($FF10)
+; -- Sweep register (R/W)
+; --
+; -- Bit 6-4 - Sweep Time
+; -- Bit 3   - Sweep Increase/Decrease
+; --           0: Addition    (frequency increases???)
+; --           1: Subtraction (frequency increases???)
+; -- Bit 2-0 - Number of sweep shift (# 0-7)
+; -- Sweep Time: (n*7.8ms)
+; --
+rNR10 EQU $FF10
+rAUD1SWEEP EQU rNR10
+
+AUD1SWEEP_UP   EQU %00000000
+AUD1SWEEP_DOWN EQU %00001000
+
+
+; --
+; -- AUD1LEN/NR11 ($FF11)
+; -- Sound length/Wave pattern duty (R/W)
+; --
+; -- Bit 7-6 - Wave Pattern Duty (00:12.5% 01:25% 10:50% 11:75%)
+; -- Bit 5-0 - Sound length data (# 0-63)
+; --
+rNR11 EQU $FF11
+rAUD1LEN EQU rNR11
+
+
+; --
+; -- AUD1ENV/NR12 ($FF12)
+; -- Envelope (R/W)
+; --
+; -- Bit 7-4 - Initial value of envelope
+; -- Bit 3   - Envelope UP/DOWN
+; --           0: Decrease
+; --           1: Range of increase
+; -- Bit 2-0 - Number of envelope sweep (# 0-7)
+; --
+rNR12 EQU $FF12
+rAUD1ENV EQU rNR12
+
+
+; --
+; -- AUD1LOW/NR13 ($FF13)
+; -- Frequency low byte (W)
+; --
+rNR13 EQU $FF13
+rAUD1LOW EQU rNR13
+
+
+; --
+; -- AUD1HIGH/NR14 ($FF14)
+; -- Frequency high byte (W)
+; --
+; -- Bit 7   - Initial (when set, sound restarts)
+; -- Bit 6   - Counter/consecutive selection
+; -- Bit 2-0 - Frequency's higher 3 bits
+; --
+rNR14 EQU $FF14
+rAUD1HIGH EQU rNR14
+
+
+; --
+; -- AUD2LEN/NR21 ($FF16)
+; -- Sound Length; Wave Pattern Duty (R/W)
+; --
+; -- see AUD1LEN for info
+; --
+rNR21 EQU $FF16
+rAUD2LEN EQU rNR21
+
+
+; --
+; -- AUD2ENV/NR22 ($FF17)
+; -- Envelope (R/W)
+; --
+; -- see AUD1ENV for info
+; --
+rNR22 EQU $FF17
+rAUD2ENV EQU rNR22
+
+
+; --
+; -- AUD2LOW/NR23 ($FF18)
+; -- Frequency low byte (W)
+; --
+rNR23 EQU $FF18
+rAUD2LOW EQU rNR23
+
+
+; --
+; -- AUD2HIGH/NR24 ($FF19)
+; -- Frequency high byte (W)
+; --
+; -- see AUD1HIGH for info
+; --
+rNR24 EQU $FF19
+rAUD2HIGH EQU rNR24
+
+
+; --
+; -- AUD3ENA/NR30 ($FF1A)
+; -- Sound on/off (R/W)
+; --
+; -- Bit 7   - Sound ON/OFF (1=ON,0=OFF)
+; --
+rNR30 EQU $FF1A
+rAUD3ENA EQU rNR30
+
+
+; --
+; -- AUD3LEN/NR31 ($FF1B)
+; -- Sound length (R/W)
+; --
+; -- Bit 7-0 - Sound length
+; --
+rNR31 EQU $FF1B
+rAUD3LEN EQU rNR31
+
+
+; --
+; -- AUD3LEVEL/NR32 ($FF1C)
+; -- Select output level
+; --
+; -- Bit 6-5 - Select output level
+; --           00: 0/1 (mute)
+; --           01: 1/1
+; --           10: 1/2
+; --           11: 1/4
+; --
+rNR32 EQU $FF1C
+rAUD3LEVEL EQU rNR32
+
+
+; --
+; -- AUD3LOW/NR33 ($FF1D)
+; -- Frequency low byte (W)
+; --
+; -- see AUD1LOW for info
+; --
+rNR33 EQU $FF1D
+rAUD3LOW EQU rNR33
+
+
+; --
+; -- AUD3HIGH/NR34 ($FF1E)
+; -- Frequency high byte (W)
+; --
+; -- see AUD1HIGH for info
+; --
+rNR34 EQU $FF1E
+rAUD3HIGH EQU rNR34
+
+
+; --
+; -- AUD4LEN/NR41 ($FF20)
+; -- Sound length (R/W)
+; --
+; -- Bit 5-0 - Sound length data (# 0-63)
+; --
+rNR41 EQU $FF20
+rAUD4LEN EQU rNR41
+
+
+; --
+; -- AUD4ENV/NR42 ($FF21)
+; -- Envelope (R/W)
+; --
+; -- see AUD1ENV for info
+; --
+rNR42 EQU $FF21
+rAUD4ENV EQU rNR42
+
+
+; --
+; -- AUD4POLY/NR43 ($FF22)
+; -- Polynomial counter (R/W)
+; --
+; -- Bit 7-4 - Selection of the shift clock frequency of the (scf)
+; --           polynomial counter (0000-1101)
+; --           freq=drf*1/2^scf (not sure)
+; -- Bit 3 -   Selection of the polynomial counter's step
+; --           0: 15 steps
+; --           1: 7 steps
+; -- Bit 2-0 - Selection of the dividing ratio of frequencies (drf)
+; --           000: f/4   001: f/8   010: f/16  011: f/24
+; --           100: f/32  101: f/40  110: f/48  111: f/56  (f=4.194304 Mhz)
+; --
+rNR43 EQU $FF22
+rAUD4POLY EQU rNR43
+
+
+; --
+; -- AUD4GO/NR44 ($FF23)
+; --
+; -- Bit 7 -   Inital
+; -- Bit 6 -   Counter/consecutive selection
+; --
+rNR44 EQU $FF23
+rAUD4GO EQU rNR44
+
+
+; --
+; -- AUDVOL/NR50 ($FF24)
+; -- Channel control / ON-OFF / Volume (R/W)
+; --
+; -- Bit 7   - Vin->SO2 ON/OFF (Vin??)
+; -- Bit 6-4 - SO2 output level (volume) (# 0-7)
+; -- Bit 3   - Vin->SO1 ON/OFF (Vin??)
+; -- Bit 2-0 - SO1 output level (volume) (# 0-7)
+; --
+rNR50 EQU $FF24
+rAUDVOL EQU rNR50
+
+AUDVOL_VIN_LEFT  EQU %10000000 ; SO2
+AUDVOL_VIN_RIGHT EQU %00001000 ; SO1
+
+
+; --
+; -- AUDTERM/NR51 ($FF25)
+; -- Selection of Sound output terminal (R/W)
+; --
+; -- Bit 7   - Output sound 4 to SO2 terminal
+; -- Bit 6   - Output sound 3 to SO2 terminal
+; -- Bit 5   - Output sound 2 to SO2 terminal
+; -- Bit 4   - Output sound 1 to SO2 terminal
+; -- Bit 3   - Output sound 4 to SO1 terminal
+; -- Bit 2   - Output sound 3 to SO1 terminal
+; -- Bit 1   - Output sound 2 to SO1 terminal
+; -- Bit 0   - Output sound 0 to SO1 terminal
+; --
+rNR51 EQU $FF25
+rAUDTERM EQU rNR51
+
+; SO2
+AUDTERM_4_LEFT  EQU %10000000
+AUDTERM_3_LEFT  EQU %01000000
+AUDTERM_2_LEFT  EQU %00100000
+AUDTERM_1_LEFT  EQU %00010000
+; SO1
+AUDTERM_4_RIGHT EQU %00001000
+AUDTERM_3_RIGHT EQU %00000100
+AUDTERM_2_RIGHT EQU %00000010
+AUDTERM_1_RIGHT EQU %00000001
+
+
+; --
+; -- AUDENA/NR52 ($FF26)
+; -- Sound on/off (R/W)
+; --
+; -- Bit 7   - All sound on/off (sets all audio regs to 0!)
+; -- Bit 3   - Sound 4 ON flag (read only)
+; -- Bit 2   - Sound 3 ON flag (read only)
+; -- Bit 1   - Sound 2 ON flag (read only)
+; -- Bit 0   - Sound 1 ON flag (read only)
+; --
+rNR52 EQU $FF26
+rAUDENA EQU rNR52
+
+AUDENA_ON    EQU %10000000
+AUDENA_OFF   EQU %00000000  ; sets all audio regs to 0!
+
+
+; --
+; -- LCDC ($FF40)
+; -- LCD Control (R/W)
+; --
+rLCDC EQU $FF40
+
+LCDCF_OFF     EQU %00000000 ; LCD Control Operation
+LCDCF_ON      EQU %10000000 ; LCD Control Operation
+LCDCF_WIN9800 EQU %00000000 ; Window Tile Map Display Select
+LCDCF_WIN9C00 EQU %01000000 ; Window Tile Map Display Select
+LCDCF_WINOFF  EQU %00000000 ; Window Display
+LCDCF_WINON   EQU %00100000 ; Window Display
+LCDCF_BG8800  EQU %00000000 ; BG & Window Tile Data Select
+LCDCF_BG8000  EQU %00010000 ; BG & Window Tile Data Select
+LCDCF_BG9800  EQU %00000000 ; BG Tile Map Display Select
+LCDCF_BG9C00  EQU %00001000 ; BG Tile Map Display Select
+LCDCF_OBJ8    EQU %00000000 ; OBJ Construction
+LCDCF_OBJ16   EQU %00000100 ; OBJ Construction
+LCDCF_OBJOFF  EQU %00000000 ; OBJ Display
+LCDCF_OBJON   EQU %00000010 ; OBJ Display
+LCDCF_BGOFF   EQU %00000000 ; BG Display
+LCDCF_BGON    EQU %00000001 ; BG Display
+; "Window Character Data Select" follows BG
+
+
+; --
+; -- STAT ($FF41)
+; -- LCDC Status   (R/W)
+; --
+rSTAT EQU $FF41
+
+STATF_LYC     EQU  %01000000 ; LYC=LY Coincidence (Selectable)
+STATF_MODE10  EQU  %00100000 ; Mode 10
+STATF_MODE01  EQU  %00010000 ; Mode 01 (V-Blank)
+STATF_MODE00  EQU  %00001000 ; Mode 00 (H-Blank)
+STATF_LYCF    EQU  %00000100 ; Coincidence Flag
+STATF_HBL     EQU  %00000000 ; H-Blank
+STATF_VBL     EQU  %00000001 ; V-Blank
+STATF_OAM     EQU  %00000010 ; OAM-RAM is used by system
+STATF_LCD     EQU  %00000011 ; Both OAM and VRAM used by system
+STATF_BUSY    EQU  %00000010 ; When set, VRAM access is unsafe
+
+
+; --
+; -- SCY ($FF42)
+; -- Scroll Y (R/W)
+; --
+rSCY EQU $FF42
+
+
+; --
+; -- SCX ($FF43)
+; -- Scroll X (R/W)
+; --
+rSCX EQU $FF43
+
+
+; --
+; -- LY ($FF44)
+; -- LCDC Y-Coordinate (R)
+; --
+; -- Values range from 0->153. 144->153 is the VBlank period.
+; --
+rLY EQU $FF44
+
+
+; --
+; -- LYC ($FF45)
+; -- LY Compare (R/W)
+; --
+; -- When LY==LYC, STATF_LYCF will be set in STAT
+; --
+rLYC EQU $FF45
+
+
+; --
+; -- DMA ($FF46)
+; -- DMA Transfer and Start Address (W)
+; --
+rDMA EQU $FF46
+
+
+; --
+; -- BGP ($FF47)
+; -- BG Palette Data (W)
+; --
+; -- Bit 7-6 - Intensity for %11
+; -- Bit 5-4 - Intensity for %10
+; -- Bit 3-2 - Intensity for %01
+; -- Bit 1-0 - Intensity for %00
+; --
+rBGP EQU $FF47
+
+
+; --
+; -- OBP0 ($FF48)
+; -- Object Palette 0 Data (W)
+; --
+; -- See BGP for info
+; --
+rOBP0 EQU $FF48
+
+
+; --
+; -- OBP1 ($FF49)
+; -- Object Palette 1 Data (W)
+; --
+; -- See BGP for info
+; --
+rOBP1 EQU $FF49
+
+
+; --
+; -- WY ($FF4A)
+; -- Window Y Position (R/W)
+; --
+; -- 0 <= WY <= 143
+; -- When WY = 0, the window is displayed from the top edge of the LCD screen.
+; --
+rWY EQU $FF4A
+
+
+; --
+; -- WX ($FF4B)
+; -- Window X Position (R/W)
+; --
+; -- 7 <= WX <= 166
+; -- When WX = 7, the window is displayed from the left edge of the LCD screen.
+; -- Values of 0-6 and 166 are unreliable due to hardware bugs.
+; --
+rWX EQU $FF4B
+
+
+; --
+; -- SPEED ($FF4D)
+; -- Select CPU Speed (R/W)
+; --
+rKEY1 EQU $FF4D
+rSPD  EQU rKEY1
+
+KEY1F_DBLSPEED EQU %10000000 ; 0=Normal Speed, 1=Double Speed (R)
+KEY1F_PREPARE  EQU %00000001 ; 0=No, 1=Prepare (R/W)
+
+
+; --
+; -- VBK ($FF4F)
+; -- Select Video RAM Bank (R/W)
+; --
+; -- Bit 0 - Bank Specification (0: Specify Bank 0; 1: Specify Bank 1)
+; --
+rVBK EQU $FF4F
+
+
+; --
+; -- HDMA1 ($FF51)
+; -- High byte for Horizontal Blanking/General Purpose DMA source address (W)
+; -- CGB Mode Only
+; --
+rHDMA1 EQU $FF51
+
+
+; --
+; -- HDMA2 ($FF52)
+; -- Low byte for Horizontal Blanking/General Purpose DMA source address (W)
+; -- CGB Mode Only
+; --
+rHDMA2 EQU $FF52
+
+
+; --
+; -- HDMA3 ($FF53)
+; -- High byte for Horizontal Blanking/General Purpose DMA destination address (W)
+; -- CGB Mode Only
+; --
+rHDMA3 EQU $FF53
+
+
+; --
+; -- HDMA4 ($FF54)
+; -- Low byte for Horizontal Blanking/General Purpose DMA destination address (W)
+; -- CGB Mode Only
+; --
+rHDMA4 EQU $FF54
+
+
+; --
+; -- HDMA5 ($FF55)
+; -- Transfer length (in tiles minus 1)/mode/start for Horizontal Blanking, General Purpose DMA (R/W)
+; -- CGB Mode Only
+; --
+rHDMA5 EQU $FF55
+
+HDMA5F_MODE_GP  EQU %00000000 ; General Purpose DMA (W)
+HDMA5F_MODE_HBL EQU %10000000 ; HBlank DMA (W)
+
+; -- Once DMA has started, use HDMA5F_BUSY to check when the transfer is complete
+HDMA5F_BUSY EQU %10000000 ; 0=Busy (DMA still in progress), 1=Transfer complete (R)
+
+
+; --
+; -- RP ($FF56)
+; -- Infrared Communications Port (R/W)
+; -- CGB Mode Only
+; --
+rRP EQU $FF56
+
+RPF_ENREAD   EQU %11000000
+RPF_DATAIN   EQU %00000010 ; 0=Receiving IR Signal, 1=Normal
+RPF_WRITE_HI EQU %00000001
+RPF_WRITE_LO EQU %00000000
+
+
+; --
+; -- BCPS ($FF68)
+; -- Background Color Palette Specification (R/W)
+; --
+rBCPS EQU $FF68
+
+BCPSF_AUTOINC EQU %10000000 ; Auto Increment (0=Disabled, 1=Increment after Writing)
+
+
+; --
+; -- BCPD ($FF69)
+; -- Background Color Palette Data (R/W)
+; --
+rBCPD EQU $FF69
+
+
+; --
+; -- OCPS ($FF6A)
+; -- Object Color Palette Specification (R/W)
+; --
+rOCPS EQU $FF6A
+
+OCPSF_AUTOINC EQU %10000000 ; Auto Increment (0=Disabled, 1=Increment after Writing)
+
+
+; --
+; -- OCPD ($FF6B)
+; -- Object Color Palette Data (R/W)
+; --
+rOCPD EQU $FF6B
+
+
+; --
+; -- SMBK/SVBK ($FF70)
+; -- Select Main RAM Bank (R/W)
+; --
+; -- Bit 2-0 - Bank Specification (0,1: Specify Bank 1; 2-7: Specify Banks 2-7)
+; --
+rSVBK EQU $FF70
+rSMBK EQU rSVBK
+
+
+; --
+; -- PCM12 ($FF76)
+; -- Sound channel 1&2 PCM amplitude (R)
+; --
+; -- Bit 7-4 - Copy of sound channel 2's PCM amplitude
+; -- Bit 3-0 - Copy of sound channel 1's PCM amplitude
+; --
+rPCM12 EQU $FF76
+
+
+; --
+; -- PCM34 ($FF77)
+; -- Sound channel 3&4 PCM amplitude (R)
+; --
+; -- Bit 7-4 - Copy of sound channel 4's PCM amplitude
+; -- Bit 3-0 - Copy of sound channel 3's PCM amplitude
+; --
+rPCM34 EQU $FF77
+
+
+; --
+; -- IE ($FFFF)
+; -- Interrupt Enable (R/W)
+; --
+rIE EQU $FFFF
+
+IEF_HILO   EQU %00010000 ; Transition from High to Low of Pin number P10-P13
+IEF_SERIAL EQU %00001000 ; Serial I/O transfer end
+IEF_TIMER  EQU %00000100 ; Timer Overflow
+IEF_LCDC   EQU %00000010 ; LCDC (see STAT)
+IEF_VBLANK EQU %00000001 ; V-Blank
+
+
+;***************************************************************************
+;*
+;* Flags common to multiple sound channels
+;*
+;***************************************************************************
+
+; --
+; -- Square wave duty cycle
+; --
+; -- Can be used with AUD1LEN and AUD2LEN
+; -- See AUD1LEN for more info
+; --
+AUDLEN_DUTY_12_5    EQU %00000000 ; 12.5%
+AUDLEN_DUTY_25      EQU %01000000 ; 25%
+AUDLEN_DUTY_50      EQU %10000000 ; 50%
+AUDLEN_DUTY_75      EQU %11000000 ; 75%
+
+
+; --
+; -- Audio envelope flags
+; --
+; -- Can be used with AUD1ENV, AUD2ENV, AUD4ENV
+; -- See AUD1ENV for more info
+; --
+AUDENV_UP           EQU %00001000
+AUDENV_DOWN         EQU %00000000
+
+
+; --
+; -- Audio trigger flags
+; --
+; -- Can be used with AUD1HIGH, AUD2HIGH, AUD3HIGH
+; -- See AUD1HIGH for more info
+; --
+
+AUDHIGH_RESTART     EQU %10000000
+AUDHIGH_LENGTH_ON   EQU %01000000
+AUDHIGH_LENGTH_OFF  EQU %00000000
+
+
+;***************************************************************************
+;*
+;* CPU values on bootup (a=type, b=qualifier)
+;*
+;***************************************************************************
+
+BOOTUP_A_DMG    EQU $01 ; Dot Matrix Game
+BOOTUP_A_CGB    EQU $11 ; Color GameBoy
+BOOTUP_A_MGB    EQU $FF ; Mini GameBoy (Pocket GameBoy)
+
+; if a=BOOTUP_A_CGB, bit 0 in b can be checked to determine if real CGB or
+; other system running in GBC mode
+BOOTUP_B_CGB    EQU %00000000
+BOOTUP_B_AGB    EQU %00000001   ; GBA, GBA SP, Game Boy Player, or New GBA SP
+
+
+;***************************************************************************
+;*
+;* Cart related
+;*
+;***************************************************************************
+
+; $0143 Color GameBoy compatibility code
+CART_COMPATIBLE_DMG     EQU $00
+CART_COMPATIBLE_DMG_GBC EQU $80
+CART_COMPATIBLE_GBC     EQU $C0
+
+; $0146 GameBoy/Super GameBoy indicator
+CART_INDICATOR_GB       EQU $00
+CART_INDICATOR_SGB      EQU $03
+
+; $0147 Cartridge type
+CART_ROM                     EQU $00
+CART_ROM_MBC1                EQU $01
+CART_ROM_MBC1_RAM            EQU $02
+CART_ROM_MBC1_RAM_BAT        EQU $03
+CART_ROM_MBC2                EQU $05
+CART_ROM_MBC2_BAT            EQU $06
+CART_ROM_RAM                 EQU $08
+CART_ROM_RAM_BAT             EQU $09
+CART_ROM_MMM01               EQU $0B
+CART_ROM_MMM01_RAM           EQU $0C
+CART_ROM_MMM01_RAM_BAT       EQU $0D
+CART_ROM_MBC3_BAT_RTC        EQU $0F
+CART_ROM_MBC3_RAM_BAT_RTC    EQU $10
+CART_ROM_MBC3                EQU $11
+CART_ROM_MBC3_RAM            EQU $12
+CART_ROM_MBC3_RAM_BAT        EQU $13
+CART_ROM_MBC5                EQU $19
+CART_ROM_MBC5_BAT            EQU $1A
+CART_ROM_MBC5_RAM_BAT        EQU $1B
+CART_ROM_MBC5_RUMBLE         EQU $1C
+CART_ROM_MBC5_RAM_RUMBLE     EQU $1D
+CART_ROM_MBC5_RAM_BAT_RUMBLE EQU $1E
+CART_ROM_MBC7_RAM_BAT_GYRO   EQU $22
+CART_ROM_POCKET_CAMERA       EQU $FC
+CART_ROM_BANDAI_TAMA5        EQU $FD
+CART_ROM_HUDSON_HUC3         EQU $FE
+CART_ROM_HUDSON_HUC1         EQU $FF
+
+; $0148 ROM size
+; these are kilobytes
+CART_ROM_32KB   EQU $00 ; 2 banks
+CART_ROM_64KB   EQU $01 ; 4 banks
+CART_ROM_128KB  EQU $02 ; 8 banks
+CART_ROM_256KB  EQU $03 ; 16 banks
+CART_ROM_512KB  EQU $04 ; 32 banks
+CART_ROM_1024KB EQU $05 ; 64 banks
+CART_ROM_2048KB EQU $06 ; 128 banks
+CART_ROM_4096KB EQU $07 ; 256 banks
+CART_ROM_8192KB EQU $08 ; 512 banks
+CART_ROM_1152KB EQU $52 ; 72 banks
+CART_ROM_1280KB EQU $53 ; 80 banks
+CART_ROM_1536KB EQU $54 ; 96 banks
+
+; $0149 SRAM size
+; these are kilobytes
+CART_SRAM_NONE  EQU 0
+CART_SRAM_2KB   EQU 1 ; 1 incomplete bank
+CART_SRAM_8KB   EQU 2 ; 1 bank
+CART_SRAM_32KB  EQU 3 ; 4 banks
+CART_SRAM_128KB EQU 4 ; 16 banks
+
+CART_SRAM_ENABLE  EQU $0A
+CART_SRAM_DISABLE EQU $00
+
+; $014A Destination code
+CART_DEST_JAPANESE     EQU $00
+CART_DEST_NON_JAPANESE EQU $01
+
+
+;***************************************************************************
+;*
+;* Keypad related
+;*
+;***************************************************************************
+
+PADF_DOWN   EQU $80
+PADF_UP     EQU $40
+PADF_LEFT   EQU $20
+PADF_RIGHT  EQU $10
+PADF_START  EQU $08
+PADF_SELECT EQU $04
+PADF_B      EQU $02
+PADF_A      EQU $01
+
+PADB_DOWN   EQU $7
+PADB_UP     EQU $6
+PADB_LEFT   EQU $5
+PADB_RIGHT  EQU $4
+PADB_START  EQU $3
+PADB_SELECT EQU $2
+PADB_B      EQU $1
+PADB_A      EQU $0
+
+
+;***************************************************************************
+;*
+;* Screen related
+;*
+;***************************************************************************
+
+SCRN_X    EQU 160 ; Width of screen in pixels
+SCRN_Y    EQU 144 ; Height of screen in pixels
+SCRN_X_B  EQU 20  ; Width of screen in bytes
+SCRN_Y_B  EQU 18  ; Height of screen in bytes
+
+SCRN_VX   EQU 256 ; Virtual width of screen in pixels
+SCRN_VY   EQU 256 ; Virtual height of screen in pixels
+SCRN_VX_B EQU 32  ; Virtual width of screen in bytes
+SCRN_VY_B EQU 32  ; Virtual height of screen in bytes
+
+
+;***************************************************************************
+;*
+;* OAM related
+;*
+;***************************************************************************
+
+; OAM attributes
+; each entry in OAM RAM is 4 bytes (sizeof_OAM_ATTRS)
+RSRESET
+OAMA_Y              RB  1   ; y pos
+OAMA_X              RB  1   ; x pos
+OAMA_TILEID         RB  1   ; tile id
+OAMA_FLAGS          RB  1   ; flags (see below)
+sizeof_OAM_ATTRS    RB  0
+
+OAM_COUNT           EQU 40  ; number of OAM entries in OAM RAM
+
+; flags
+OAMF_PRI        EQU %10000000 ; Priority
+OAMF_YFLIP      EQU %01000000 ; Y flip
+OAMF_XFLIP      EQU %00100000 ; X flip
+OAMF_PAL0       EQU %00000000 ; Palette number; 0,1 (DMG)
+OAMF_PAL1       EQU %00010000 ; Palette number; 0,1 (DMG)
+OAMF_BANK0      EQU %00000000 ; Bank number; 0,1 (GBC)
+OAMF_BANK1      EQU %00001000 ; Bank number; 0,1 (GBC)
+
+OAMF_PALMASK    EQU %00000111 ; Palette (GBC)
+
+OAMB_PRI        EQU 7 ; Priority
+OAMB_YFLIP      EQU 6 ; Y flip
+OAMB_XFLIP      EQU 5 ; X flip
+OAMB_PAL1       EQU 4 ; Palette number; 0,1 (DMG)
+OAMB_BANK1      EQU 3 ; Bank number; 0,1 (GBC)
+
+
+;*
+;* Nintendo scrolling logo
+;* (Code won't work on a real GameBoy)
+;* (if next lines are altered.)
+NINTENDO_LOGO : MACRO
+    DB  $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D
+    DB  $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99
+    DB  $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
+ENDM
+
+    ENDC ;HARDWARE_INC
diff --git a/gbsdk/inc/sdk/joypad.h b/gbsdk/inc/sdk/joypad.h
new file mode 100644
index 0000000..5102a6c
--- /dev/null
+++ b/gbsdk/inc/sdk/joypad.h
@@ -0,0 +1,20 @@
+#ifndef GBSDK_JOYPAD_H
+#define GBSDK_JOYPAD_H
+
+#include <stdint.h>
+
+#define PAD_DOWN   0x80
+#define PAD_UP     0x40
+#define PAD_LEFT   0x20
+#define PAD_RIGHT  0x10
+#define PAD_START  0x08
+#define PAD_SELECT 0x04
+#define PAD_B      0x02
+#define PAD_A      0x01
+
+extern uint8_t joypad_state;
+extern uint8_t joypad_pressed;
+
+void joypad_update(void) __preserves_regs(b, c);
+
+#endif//GBSDK_JOYPAD_H
diff --git a/gbsdk/inc/sdk/oam.h b/gbsdk/inc/sdk/oam.h
new file mode 100644
index 0000000..dd6fe35
--- /dev/null
+++ b/gbsdk/inc/sdk/oam.h
@@ -0,0 +1,19 @@
+#ifndef GBSDK_OAM_H
+#define GBSDK_OAM_H
+
+#include <stdint.h>
+#include <sdk/hardware.h>
+
+
+struct oam_entry {
+    uint8_t y;
+    uint8_t x;
+    uint8_t tile;
+    uint8_t attr;
+};
+extern struct oam_entry shadow_oam[40];
+
+void oam_init(void) __preserves_regs(b);
+void oam_dma_copy(void) __preserves_regs(b, c, d, e, h, l);
+
+#endif//GBSDK_OAM_H
diff --git a/gbsdk/inc/sdk/sgb.h b/gbsdk/inc/sdk/sgb.h
new file mode 100644
index 0000000..c5d2127
--- /dev/null
+++ b/gbsdk/inc/sdk/sgb.h
@@ -0,0 +1,39 @@
+#ifndef GBSDK_SGB_H
+#define GBSDK_SGB_H
+
+#include <stdint.h>
+
+#if SGB
+
+#define SGB_PAL01       0x00    //Set SGB Palette 0 & 1
+#define SGB_PAL23       0x01    //Set SGB Palette 2 & 3
+#define SGB_PAL03       0x02    //Set SGB Palette 0 & 3
+#define SGB_PAL12       0x03    //Set SGB Palette 1 & 2
+#define SGB_ATTR_BLK    0x04    //"Block" Area Designation Mode
+#define SGB_ATTR_LIN    0x05    //"Line" Area Designation Mode
+#define SGB_ATTR_DIV    0x06    //"Divide" Area Designation Mode
+#define SGB_ATTR_CHR    0x07    //"1CHR" Area Designation Mode
+#define SGB_SOUND       0x08    //Sound On/Off
+#define SGB_SOU_TRN     0x09    //Transfer Sound PRG/DATA
+#define SGB_PAL_SET     0x0A    //Set SGB Palette Indirect
+#define SGB_PAL_TRN     0x0B    //Set System Color Palette Data
+#define SGB_ATRC_EN     0x0C    //Enable/disable Attraction Mode
+#define SGB_TEST_EN     0x0D    //Speed Function
+#define SGB_ICON_EN     0x0E    //SGB Function
+#define SGB_DATA_SND    0x0F    //SUPER NES WRAM Transfer 1
+#define SGB_DATA_TRN    0x10    //SUPER NES WRAM Transfer 2
+#define SGB_MLT_REQ     0x11    //Controller 2 Request
+#define SGB_JUMP        0x12    //Set SNES Program Counter
+#define SGB_CHR_TRN     0x13    //Transfer Character Font Data
+#define SGB_PCT_TRN     0x14    //Set Screen Data Color Data
+#define SGB_ATTR_TRN    0x15    //Set Attribute from ATF
+#define SGB_ATTR_SET    0x16    //Set Data to ATF
+#define SGB_MASK_EN     0x17    //Game Boy Window Mask
+#define SGB_OBJ_TRN     0x18    //Super NES OBJ Mode
+
+#define SGB_HEADER(command, length) ((uint8_t)(((command) << 3) | (length)))
+
+void sgb_send(const uint8_t* packet);
+#endif
+
+#endif
diff --git a/gbsdk/inc/sdk/video.h b/gbsdk/inc/sdk/video.h
new file mode 100644
index 0000000..7cba700
--- /dev/null
+++ b/gbsdk/inc/sdk/video.h
@@ -0,0 +1,40 @@
+#ifndef GBSDK_VIDEO_H
+#define GBSDK_VIDEO_H
+
+#include <stdint.h>
+#include <sdk/hardware.h>
+
+
+//Turn off the LCD, with the proper checks that this happens during VBLANK
+void lcd_off(void) __preserves_regs(b, c, d, e, h, l);
+
+//Copy to VRAM with STAT checks, so these function are safe to write to VRAM at any time.
+void vram_memcpy(uint16_t dst, void* src, uint16_t size) __preserves_regs(b, c);
+void vram_memset(uint16_t dst, uint8_t value, uint16_t size) __preserves_regs(b, c);
+inline void vram_set(uint16_t dst, uint8_t value) {
+    while(rSTAT & STAT_BUSY) {}
+    *((uint8_t*)dst) = value;
+}
+
+#if CGB
+#define PAL24(rgb) (((rgb & 0xF80000) >> 19) | ((rgb & 0x00F800) >> 6) | ((rgb & 0x0000F8) << 7))
+
+void cgb_background_palette(uint16_t* palette) __preserves_regs(b, c);
+void cgb_object_palette(uint16_t* palette) __preserves_regs(b, c);
+inline void cgb_gdma(uint16_t dst, const void* src, uint8_t count) {
+    rHDMA1 = ((uint16_t)src) >> 8;
+    rHDMA2 = ((uint16_t)src) & 0xFF;
+    rHDMA3 = dst >> 8;
+    rHDMA4 = dst & 0xFF;
+    rHDMA5 = count - 1;
+}
+inline void cgb_hdma(uint16_t dst, const void* src, uint8_t count) {
+    rHDMA1 = ((uint16_t)src) >> 8;
+    rHDMA2 = ((uint16_t)src) & 0xFF;
+    rHDMA3 = dst >> 8;
+    rHDMA4 = dst & 0xFF;
+    rHDMA5 = (count - 1) | 0x80;
+}
+#endif
+
+#endif//GBSDK_VIDEO_H
diff --git a/gbsdk/rules.mk b/gbsdk/rules.mk
new file mode 100644
index 0000000..8e8d2a2
--- /dev/null
+++ b/gbsdk/rules.mk
@@ -0,0 +1,169 @@
+.PHONY: all clean
+
+MYDIR     := $(dir $(lastword $(MAKEFILE_LIST)))
+
+ifndef PROJECT_NAME
+$(error PROJECT_NAME is not set to the name of your rom.)
+endif
+ifndef MBC
+$(error MBC is not set. Should be set to the MBC name or value you want. Example "MBC5+RAM+BATTERY")
+endif
+ifndef TARGETS
+$(error TARGETS is not set. Should be a combination of DMG SGB CGB)
+endif
+ifneq ($(filter-out DMG SGB CGB,$(TARGETS)),)
+$(error TARGETS should be a combination of DMG SGB CGB, unknown: $(filter-out DMG SGB CGB,$(TARGETS)))
+endif
+
+MAPS      := $(shell find level/ -type f -name '*.png' -not -name '*_coll.png')
+SRC       := $(shell find src/ -type f -name '*.c') $(shell find $(MYDIR)/src/ -type f -name '*.c') $(MAPS:level/%.png=_build/level/%.c)
+ASM       := $(shell find src/ -type f -name '*.asm') $(shell find $(MYDIR)/src/ -type f -name '*.asm')
+
+# Which files do we use from the sdcc libc
+LIBC    := _memset.c gbz80/memcpy.s
+LIBC    += _divuchar.c _divschar.c _muluchar.c _mulschar.c _modschar.c _moduchar.c
+LIBC    += _divuint.c _divsint.c _mulint.c _modsint.c _moduint.c
+# the 32 bit functions use 10% of ROM0, so do not include them
+#LIBC    += _divulong.c _divslong.c _mullong.c _modslong.c _modulong.c
+LIBC_PATH := $(subst \,/,$(shell sdcc -mgbz80 --print-search-dirs | grep gbz80 | tail -n 1))/../src
+
+ifneq (1,$(words [$(LIBC_PATH)]))
+$(error "your environment or sdcc is installed in a path with spaces in it, this is not allowed, as it will break sdcc")
+endif
+
+Q ?= @
+
+BUILD    := _build
+TOOLS    := $(MYDIR)/tools
+OBJS     := $(patsubst %, $(BUILD)/%.o, $(ASM) $(SRC)) $(patsubst %, $(BUILD)/libc/%.o, $(LIBC)) $(BUILD)/gsinit.end.o
+
+CFLAGS   := -mgbz80 -Isrc/ -I$(MYDIR)/inc -I$(BUILD)/level
+ASFLAGS  := -isrc/ -i$(MYDIR)/inc -i$(BUILD)/assets/ -Wall
+LDFLAGS  := --pad 0xFF
+FIXFLAGS := --validate --pad-value 0xFF --title "$(PROJECT_NAME)" --mbc-type "$(MBC)" -l 0x33
+ROM_EXTENSION := gb
+# Replace spaces with underscores in the project name.
+PROJECT_NAME := $(subst $() $(),_,$(PROJECT_NAME))
+
+ifeq ($(filter CGB,$(TARGETS)),) # Not targeting CGB, so disable CGB features
+	CFLAGS  += -DCGB=0
+	ASFLAGS += -DCGB=0
+	LDFLAGS += --dmg
+else
+	CFLAGS  += -DCGB=1
+	ASFLAGS += -DCGB=1
+	ifeq ($(filter DMG,$(TARGETS))$(filter SGB,$(TARGETS)),) # Check if not targeting both CGB and DMG
+		FIXFLAGS += --color-only
+	else
+		FIXFLAGS += --color-compatible
+	endif
+    ROM_EXTENSION := gbc
+endif
+ifeq ($(filter SGB,$(TARGETS)),) # Not targeting SGB, so disable SGB features
+	CFLAGS  += -DSGB=0
+	ASFLAGS += -DSGB=0
+else # Targeting SGB as well
+	CFLAGS  += -DSGB=1
+	ASFLAGS += -DSGB=1
+	FIXFLAGS += --sgb-compatible
+endif
+ifneq ($(findstring RAM,$(MBC)),)
+	FIXFLAGS += --ram-size 2
+endif
+
+all: $(PROJECT_NAME).$(ROM_EXTENSION)
+
+# Rules to make c files
+$(BUILD)/%.c.as: %.c
+	@echo Compiling $<
+	@mkdir -p $(dir $@)
+	$(Q)sdcc $(CFLAGS) -S $< -o $@ -Wp "-MQ $@ -MD $(@:.as=.as.d)"
+-include $(patsubst %.c, $(BUILD)/%.c.as.d, $(SRC))
+
+$(BUILD)/libc/%.c.as: $(LIBC_PATH)/%.c
+	@echo Compiling $<
+	@mkdir -p $(dir $@)
+	$(Q)sdcc $(CFLAGS) -S $< -o $@
+
+$(BUILD)/%.c.asm: $(BUILD)/%.c.as $(TOOLS)/asmconvert.py
+	$(Q)python3 $(TOOLS)/asmconvert.py $(notdir $<) < $< > $@
+
+$(BUILD)/%.c.asm.d: $(BUILD)/%.c.asm
+	@mkdir -p $(dir $@)
+	$(Q)rgbasm $(ASFLAGS) $< -M $@ -MT $(@:.asm.d=.o) -MT $@ -MG
+#	rgbds dependency generation is broken, as it stops after the first missing file. so list all incbins always
+	$(Q)cat $< | grep -i '^ *INCBIN' | sed -E 's/ *incbin *"([^"]*)"/$(subst /,\/,$(@:.asm.d=.o)): \1/gI' >> $@
+-include $(patsubst %.c, $(BUILD)/%.c.asm.d, $(SRC))
+
+$(BUILD)/%.c.o: $(BUILD)/%.c.asm $(BUILD)/%.c.asm.d
+	@echo "Assembling (c)" $<
+	@mkdir -p $(dir $@)
+	$(Q)rgbasm $(ASFLAGS) $< -o $@
+
+# Rules to build libc asm files
+$(BUILD)/libc/%.s.asm: $(LIBC_PATH)/%.s $(TOOLS)/asmconvert.py
+	@mkdir -p $(dir $@)
+	$(Q)python3 $(TOOLS)/asmconvert.py $(notdir $<) < $< > $@
+
+$(BUILD)/libc/%.s.o: $(BUILD)/libc/%.s.asm
+	@echo Assembling $<
+	@mkdir -p $(dir $@)
+	$(Q)rgbasm $(ASFLAGS) $< -o $@
+
+# Rules to build project asm files
+$(BUILD)/%.asm.d: %.asm
+	@mkdir -p $(dir $@)
+	$(Q)rgbasm $(ASFLAGS) $< -M $@ -MT $(@:.d=.o) -MT $@ -MG
+#	rgbds dependency generation is broken, as it stops after the first missing file. so list all incbins always
+	$(Q)cat $< | grep -i '^ *INCBIN' | sed -E 's/incbin "([^"]*)"/$(subst /,\/,$(@:.d=.o)): \1/gI' >> $@
+
+$(BUILD)/%.asm.o: %.asm $(BUILD)/%.asm.d
+	@echo Assembling $<
+	@mkdir -p $(dir $@)
+	$(Q)rgbasm $(ASFLAGS) $< -o $@
+-include $(patsubst %.asm, $(BUILD)/%.asm.d, $(ASM))
+
+# Rule to build the final rom
+$(PROJECT_NAME).$(ROM_EXTENSION) $(PROJECT_NAME).map $(PROJECT_NAME).sym: $(OBJS)
+	@echo Linking $@
+	$(Q)rgblink $(LDFLAGS) $^ -o $@ -m $(basename $@).map -n $(basename $@).sym
+	$(Q)rgbfix $(FIXFLAGS) $@
+	@python3 $(TOOLS)/romspace.py $(basename $@).map
+
+# Asset related rules
+$(BUILD)/assets/%.2bpp $(BUILD)/assets/%.map: assets/%.png
+	@echo Converting $<
+	@mkdir -p $(dir $@)
+	$(Q)rgbgfx \
+		-t "$(BUILD)/$(shell dirname $<)/$(shell basename --suffix=.png $<).map" \
+		-o "$(BUILD)/$(shell dirname $<)/$(shell basename --suffix=.png $<).2bpp" \
+		-u \
+		$<
+
+$(BUILD)/level/%.h $(BUILD)/level/%.c: level/%.png level/%_coll.png
+	@echo Generating level $<
+	@mkdir -p $(BUILD)/level
+	@cp $< $(BUILD)/level/
+	@cp $(shell dirname $<)/$(shell basename --suffix=.png $<)_coll.png $(BUILD)/level/
+	@python scripts/generate_map.py --compress 1 "$(BUILD)/$<"
+
+$(BUILD)/assets/%.oam.2bpp: assets/%.oam.png
+	@echo Converting $<
+	@mkdir -p $(dir $@)
+	$(Q)rgbgfx -h $< -o $@
+
+$(BUILD)/assets/%.1bpp: assets/%.png
+	@echo Converting $<
+	@mkdir -p $(dir $@)
+	$(Q)rgbgfx -d 1 $< -o $@
+
+# Special hack to place a ret instruction at the end of the GSINIT section.
+# This has to be linked last, as that ensures that this fragment is at the end of the "GSINIT" section.
+$(BUILD)/gsinit.end.o:
+	@/bin/echo -e 'SECTION FRAGMENT "GSINIT", ROMX, BANK[1]\n  ret' | rgbasm - -o $@
+
+clean:
+	@rm -rf $(BUILD) $(PROJECT_NAME).$(ROM_EXTENSION) $(PROJECT_NAME).map $(PROJECT_NAME).sym
+
+# Do not remove intermediate files (like assets, c->asm files, etc)
+.SECONDARY:
diff --git a/gbsdk/src/banking.asm b/gbsdk/src/banking.asm
new file mode 100644
index 0000000..5e9d1d6
--- /dev/null
+++ b/gbsdk/src/banking.asm
@@ -0,0 +1,25 @@
+INCLUDE "sdk/hardware.inc"
+
+SECTION "BankingHRAM", HRAM
+wCurrentBank::
+_current_bank:: ds 1
+
+SECTION "BankingCode", ROM0
+bankedCall::
+___sdcc_bcall_ehl::
+    ldh  a, [wCurrentBank]
+    push af
+    ld   a, e
+    ldh  [wCurrentBank], a
+    ld   [rROMB0], a
+    rst  callHL
+    pop  af
+setCurrentBank::
+    ldh  [wCurrentBank], a
+    ld   [rROMB0], a
+    ret
+
+SECTION "callHL", ROM0[$0008]
+callHL::
+___sdcc_call_hl::
+    jp   hl
diff --git a/gbsdk/src/entry.asm b/gbsdk/src/entry.asm
new file mode 100644
index 0000000..7399881
--- /dev/null
+++ b/gbsdk/src/entry.asm
@@ -0,0 +1,18 @@
+include "sdk/hardware.inc"
+
+SECTION "Header", ROM0[$100]
+    di
+    jp startRom
+    ds $150 - @
+
+SECTION "Init", ROMX, BANK[1]
+startRom:
+    ld   sp, $E000
+    call globalsInit ; init C globals
+    call _main
+    db   $DD ; lock up if main returns ($DD is an invalid opcode)
+
+
+SECTION FRAGMENT "GSINIT", ROMX, BANK[1]
+globalsInit:
+    ; This will be the first fragment of GSINIT.
diff --git a/gbsdk/src/joypad.asm b/gbsdk/src/joypad.asm
new file mode 100644
index 0000000..d06ae99
--- /dev/null
+++ b/gbsdk/src/joypad.asm
@@ -0,0 +1,48 @@
+include "sdk/hardware.inc"
+
+SECTION "gbsdk_joypad_ram", WRAM0
+_joypad_state::
+wJoypadState:: ds 1
+_joypad_pressed::
+wJoypadPressed:: ds 1
+
+
+SECTION "gbsdk_joypad_functions", ROM0
+_joypad_update::
+    ; Call this routine once per frame to update the joypad related variables.
+    ; Routine also returns the currently pressed buttons in the a register.
+    ld   hl, rP1
+    ld   [hl], P1F_GET_BTN
+    ; After the initial enable we need to read twice to ensure
+    ; we get the proper hardware state on real hardware
+    ld   a, [hl]
+    ld   a, [hl]
+    ld   [hl], P1F_GET_DPAD
+    cpl  ; Inputs are active low, so a bit being 0 is a button pressed. So we invert this.
+    and  PADF_A | PADF_B | PADF_SELECT | PADF_START
+    ld   e, a  ; Store the lower 4 button bits in e
+
+    ; We need to read rP1 8 times to ensure the proper button state is available.
+    ; This is only needed on real hardware, as it takes a while for the
+    ; inputs to change state back from the first set.
+    ld   d, 8
+:   ld   a, [hl]
+    dec  d
+    jr   nz, :-
+    ld   [hl], P1F_GET_NONE ; Disable the joypad inputs again, saves a tiny bit of power and allows the lines to settle before the next read
+
+    swap a ; We want the directional keys as upper 4 bits, so swap the nibbles.
+    cpl  ; Inputs are active low, so a bit being 0 is a button pressed. So we invert this.
+    and  PADF_RIGHT | PADF_LEFT | PADF_UP | PADF_DOWN
+    or   e
+    ld   e, a
+
+    ; Compare the new joypad state with the previous one, and store the
+    ; new bits in wJoypadPressed
+    ld   hl, wJoypadState
+    xor  [hl]
+    and  e
+    ld   [wJoypadPressed], a
+    ld   a, e
+    ld   [wJoypadState], a
+    ret
diff --git a/gbsdk/src/oam.asm b/gbsdk/src/oam.asm
new file mode 100644
index 0000000..cbe3daf
--- /dev/null
+++ b/gbsdk/src/oam.asm
@@ -0,0 +1,44 @@
+include "sdk/hardware.inc"
+
+SECTION "gbsdk_oam_memory", WRAM0, ALIGN[8]
+_shadow_oam:: ; OAM Memory is for 40 sprites with 4 bytes per sprite
+wShadowOAM::
+  ds 40 * 4
+.end:
+
+SECTION "gbsdk_oam_init_function", ROMX, BANK[1]
+oamInit::
+_oam_init::
+    ld   hl, wShadowOAM
+    xor  a
+    ld   c, wShadowOAM.end - wShadowOAM
+:   ld   [hl+], a
+    dec  c
+    jr   nz, :-
+
+    ld   hl, hOAMCopyRoutine
+    ld   de, oamCopyRoutine
+    ld   c, hOAMCopyRoutine.end - hOAMCopyRoutine
+:   ld   a, [de]
+    inc  de
+    ld   [hl+], a
+    dec  c
+    jr   nz, :-
+
+    ; We directly copy to clear the initial OAM memory, which else contains garbage.
+    jp   hOAMCopyRoutine
+
+
+oamCopyRoutine:
+LOAD "hram", HRAM
+_oam_dma_copy::
+hOAMCopyRoutine::
+  ld   a, HIGH(wShadowOAM)
+  ldh  [rDMA], a
+  ld   a, $28
+.wait:
+  dec  a
+  jr   nz, .wait
+  ret
+.end:
+ENDL
diff --git a/gbsdk/src/sgb.asm b/gbsdk/src/sgb.asm
new file mode 100644
index 0000000..908c34a
--- /dev/null
+++ b/gbsdk/src/sgb.asm
@@ -0,0 +1,44 @@
+include "sdk/hardware.inc"
+
+SECTION "gbsdk_sgb_functions", ROM0
+_sgb_send::
+    pop  de
+    pop  hl
+    ; hl=pointer to data to send
+
+    ; SGB RESET pulse
+    xor  a
+    ldh  [rP1], a
+    push hl ; done here for delay reasons
+    cpl
+    ldh  [rP1], a
+    push de ; done here for delay reasons
+    ld   e, 16 ; amount of bytes to send
+
+.byteLoop:
+    ld   a, [hl+]
+    ld   d, a   ; byte to send in d
+    ld   c, 8 ; amount of bits to send
+
+.bitLoop:
+    bit  0, d
+    ld   a, P1F_5
+    jr   z, .zero
+    ld   a, P1F_4
+.zero:
+    ldh  [rP1], a
+    rr   d                ; 2cycles
+    ld   a, P1F_5 | P1F_4 ; 2cycles
+    dec  c                ; 1cycle
+    ldh  [rP1], a
+    jr   nz, .bitLoop
+    dec  e
+    jr   nz, .byteLoop
+    ld   a, P1F_5
+    ldh  [rP1], a
+    ldh  [rP1], a ; (3)
+    ldh  [rP1], a ; (3)
+    xor  a        ; (1)
+    ldh  [rP1], a
+
+    ret
diff --git a/gbsdk/src/video.asm b/gbsdk/src/video.asm
new file mode 100644
index 0000000..ffb12e1
--- /dev/null
+++ b/gbsdk/src/video.asm
@@ -0,0 +1,116 @@
+include "sdk/hardware.inc"
+
+SECTION "gbsdk_video_functions", ROM0
+_lcd_off::
+:   ldh  a, [rLY]
+    cp   144
+    jr   c, :-
+    xor  a
+    ldh  [rLCDC], a
+    ret
+
+_vram_memcpy::
+    ld   hl, sp + 7
+    ld   a, [hl-]
+    ld   d, a
+    ld   a, [hl-]
+    ld   e, a
+    or   a, d
+    ret  z
+    ; size -> de
+
+    push bc
+     ld   a, [hl-]
+     ld   b, a
+     ld   a, [hl-]
+     ld   c, a
+     ld   a, [hl-]
+     ld   l, [hl]
+     ld   h, a
+     ; src -> bc, dst -> hl, size -> de
+     inc  d
+     inc  e
+     jr   .start
+
+.copy_loop:
+     ldh  a, [rSTAT]
+     and  a, STATF_BUSY
+     jr   nz, .copy_loop
+     ld   a, [bc]
+     ld   [hl+], a
+     inc  bc
+.start:
+     dec  e
+     jr   nz, .copy_loop
+     dec  d
+     jr   nz, .copy_loop
+
+    pop bc
+    ret
+
+_vram_memset::
+    ld   hl, sp + 6
+    ld   a, [hl-]
+    ld   d, a
+    ld   a, [hl-]
+    ld   e, a
+    or   a, d
+    ret  z
+    ; size -> de
+    push bc
+     ld   a, [hl-]
+     ld   c, a
+     ld   a, [hl-]
+     ld   l, [hl]
+     ld   h, a
+     ; value -> c, dst -> hl, size -> de
+     inc  d
+     inc  e
+     jr   .start
+
+.copy_loop:
+     ldh  a, [rSTAT]
+     and  a, STATF_BUSY
+     jr   nz, .copy_loop
+     ld   a, c
+     ld   [hl+], a
+.start:
+     dec  e
+     jr   nz, .copy_loop
+     dec  d
+     jr   nz, .copy_loop
+
+    pop bc
+    ret
+
+IF CGB
+
+_cgb_background_palette::
+    pop  de
+    pop  hl
+    push hl
+    push de
+    ld   a, BCPSF_AUTOINC
+    ldh  [rBCPS], a
+    ld   e, 8*4*2
+:   ld   a, [hl+]
+    ldh  [rBCPD], a
+    dec  e
+    jr   nz, :-
+    ret
+
+_cgb_object_palette::
+    pop  de
+    pop  hl
+    push hl
+    push de
+    ld   a, OCPSF_AUTOINC
+    ldh  [rOCPS], a
+    ld   e, 8*4*2
+:   ld   a, [hl+]
+    ldh  [rOCPD], a
+    dec  e
+    jr   nz, :-
+    ret
+
+ENDC
diff --git a/gbsdk/tools/asmconvert.py b/gbsdk/tools/asmconvert.py
new file mode 100644
index 0000000..90c8b41
--- /dev/null
+++ b/gbsdk/tools/asmconvert.py
@@ -0,0 +1,227 @@
+import sys
+import re
+
+## Need to convert asxxxx syntax to rgbds syntax
+
+module = sys.argv[1]
+
+class Token:
+    def __init__(self, kind, value, line_nr):
+        self.kind = kind
+        self.value = value
+        self.line_nr = line_nr
+
+    def isA(self, kind, value=None):
+        return self.kind == kind and (value is None or value == self.value)
+
+    def __repr__(self):
+        return "[%s:%s:%d]" % (self.kind, self.value, self.line_nr)
+
+
+class Tokenizer:
+    TOKEN_REGEX = re.compile('|'.join('(?P<%s>%s)' % pair for pair in [
+        ('HEX', r'0x[0-9A-Fa-f]+'),
+        ('ASSIGN', r'='),
+        ('ALABEL', r'\d+\$'),
+        ('NUMBER', r'\d+(\.\d*)?'),
+        ('COMMENT', r';[^\n]*'),
+        ('LABEL', r':+'),
+        ('EXPR', r'#'),
+        ('STRING', '"[^"]*"'),
+        ('DIRECTIVE', r'\.[A-Za-z_][A-Za-z0-9_\.]*'),
+        ('ID', r'[A-Za-z_][A-Za-z0-9_\.]*'),
+        ('OP', r'[+\-*/,\(\)<>]'),
+        ('NEWLINE', r'\n'),
+        ('SKIP', r'[ \t]+'),
+        ('MISMATCH', r'.'),
+    ]))
+
+    def __init__(self, code):
+        self.__tokens = []
+        line_num = 1
+        for mo in self.TOKEN_REGEX.finditer(code):
+            kind = mo.lastgroup
+            value = mo.group()
+            if kind == 'MISMATCH':
+                print("ERR:", code.split("\n")[line_num-1])
+                raise RuntimeError("Syntax error on line: %d: %s\n%s", line_num, value)
+            elif kind == 'SKIP':
+                pass
+            else:
+                if kind == 'HEX':
+                    value = "$" + value[2:]
+                if kind == 'ALABEL':
+                    value = "._ANNO_" + value[:-1]
+                    kind = "ID"
+                self.__tokens.append(Token(kind, value, line_num))
+                if kind == 'NEWLINE':
+                    line_num += 1
+        self.__tokens.append(Token('NEWLINE', '\n', line_num))
+
+    def peek(self):
+        return self.__tokens[0]
+
+    def pop(self):
+        return self.__tokens.pop(0)
+
+    def expect(self, kind, value=None):
+        pop = self.pop()
+        if not pop.isA(kind, value):
+            if value is not None:
+                raise SyntaxError("%s != %s:%s" % (pop, kind, value))
+            raise SyntaxError("%s != %s" % (pop, kind))
+
+    def __bool__(self):
+        return bool(self.__tokens)
+
+tok = Tokenizer(sys.stdin.read())
+
+def processExpression():
+    while True:
+        t = tok.peek()
+        if t.isA('EXPR'):
+            tok.pop()
+            t = tok.peek()
+        if t.isA('OP', '<'):
+            sys.stdout.write('LOW')
+            tok.pop()
+            t = tok.peek()
+        if t.isA('OP', '>'):
+            sys.stdout.write('HIGH')
+            tok.pop()
+            t = tok.peek()
+        if t.isA('OP', '('):
+            tok.pop()
+            sys.stdout.write('(')
+            processExpression()
+            t = tok.pop()
+            assert t.isA('OP', ')')
+            sys.stdout.write(')')
+        if t.isA('ID') and t.value.startswith("b_"):
+            t.value = "BANK(%s)" % (t.value[1:])
+        if t.isA('NEWLINE') or t.isA('OP', ')') or t.isA('OP', ','):
+            break
+        sys.stdout.write(t.value)
+        tok.pop()
+
+def processParameter():
+    t = tok.pop()
+    if t.isA('EXPR'):
+        processExpression()
+    elif t.isA('NEWLINE'):
+        return
+    elif t.isA('ID') or t.isA('NUMBER') or t.isA('HEX'):
+        sys.stdout.write(t.value)
+    elif t.isA('OP', '('):
+        sys.stdout.write("[")
+        processExpression()
+        t = tok.pop()
+        while not t.isA('OP', ')'):
+            sys.stdout.write(t.value)
+            t = tok.pop()
+        assert t.isA('OP', ')'), t
+        sys.stdout.write("]")
+    else:
+        raise Exception(t)
+
+while tok:
+    start = tok.pop()
+    if start.isA('NEWLINE'):
+        pass
+    elif start.isA('COMMENT'):
+        print(start.value)
+    elif start.isA('DIRECTIVE'):
+        if start.value in {'.module', '.optsdcc', '.globl'}:
+            while not tok.pop().isA('NEWLINE'):
+                pass
+        elif start.value == '.area':
+            area_name = tok.pop().value
+            if area_name == "_DATA":
+                print('SECTION "%s_%s", WRAM0' % (module, area_name))
+            elif area_name == "_DABS":
+                print('SECTION "%s_%s", SRAM' % (module, area_name))
+            elif area_name == "_HOME":
+                print('SECTION FRAGMENT "%s_%s", ROM0' % (module, area_name))
+            elif area_name == "_CODE":
+                print('SECTION FRAGMENT "%s_%s", ROM0' % (module, area_name))
+            elif area_name.startswith("_CODE_"):
+                print('SECTION FRAGMENT "%s_%s", ROMX, BANK[%d]' % (module, area_name, int(area_name[6:])))
+            elif area_name == "_CABS":
+                print('SECTION FRAGMENT "%s_%s", ROM0' % (module, area_name))
+            elif area_name == "_GSINIT":
+                print('SECTION FRAGMENT "GSINIT", ROMX, BANK[1]')
+            elif area_name == "_GSFINAL":
+                print('SECTION FRAGMENT "GSFINAL", ROMX, BANK[1]')
+            elif area_name == "_auto":
+                print('SECTION FRAGMENT "code_%s", ROMX' % (module))
+            else:
+                raise Exception(area_name)
+            while not tok.pop().isA('NEWLINE'):
+                pass
+        elif start.value == '.ds':
+            sys.stdout.write("ds ")
+            processExpression()
+            sys.stdout.write("\n")
+        elif start.value == '.ascii':
+            sys.stdout.write("db ")
+            sys.stdout.write(tok.pop().value)
+            sys.stdout.write("\n")
+        elif start.value == '.db':
+            sys.stdout.write("db ")
+            processParameter()
+            while tok.peek().isA('OP', ','):
+                sys.stdout.write(",")
+                tok.pop()
+                processParameter()
+            sys.stdout.write("\n")
+        elif start.value == '.dw':
+            sys.stdout.write("dw ")
+            processParameter()
+            while tok.peek().isA('OP', ','):
+                sys.stdout.write(",")
+                tok.pop()
+                processParameter()
+            sys.stdout.write("\n")
+        elif start.value == '.incbin':
+            sys.stdout.write("incbin ")
+            while not tok.peek().isA('NEWLINE'):
+                sys.stdout.write(tok.pop().value)
+            sys.stdout.write("\n")
+            tok.pop()
+        else:
+            raise Exception(start, tok.peek())
+    elif start.isA('ID'):
+        if tok.peek().isA('ASSIGN'):
+            tok.pop()
+            sys.stdout.write("%s = " % (start.value))
+            processExpression()
+            sys.stdout.write("\n")
+        elif tok.peek().isA('LABEL'):
+            print("%s%s" % (start.value, tok.pop().value))
+        elif start.isA('ID', 'ldhl'):
+            tok.expect('ID', 'sp')
+            tok.expect('OP', ',')
+            sys.stdout.write("ld hl, sp + ")
+            processParameter()
+            sys.stdout.write("\n")
+        elif start.isA('ID', 'lda'):
+            tok.expect('ID', 'hl')
+            tok.expect('OP', ',')
+            t = tok.pop()
+            assert t.isA('NUMBER') or t.isA('HEX')
+            tok.expect('OP', '(')
+            tok.expect('ID', 'sp')
+            tok.expect('OP', ')')
+            sys.stdout.write("ld hl, sp + %s\n" % (t.value))
+        else:
+            sys.stdout.write("%s " % (start.value))
+            if not tok.peek().isA('NEWLINE'):
+                processParameter()
+                if tok.peek().isA('OP', ','):
+                    tok.pop()
+                    sys.stdout.write(", ")
+                    processParameter()
+            sys.stdout.write("\n")
+        tok.expect('NEWLINE')
+    else:
+        raise Exception(start)
diff --git a/gbsdk/tools/romspace.py b/gbsdk/tools/romspace.py
new file mode 100644
index 0000000..bae86db
--- /dev/null
+++ b/gbsdk/tools/romspace.py
@@ -0,0 +1,16 @@
+import sys
+import re
+
+SIZE = {"ROM0": 0x4000, "ROMX": 0x4000, "WRAM0": 0x2000, "HRAM": 0x007F, "VRAM": 0x4000}
+
+area_re = re.compile(r'([A-Z0-9]+) bank #([0-9a-f]+):\n')
+slack_re = re.compile(r'    SLACK: \$([0-9a-f]+) byte')
+for line in open(sys.argv[1], "rt"):
+    area = area_re.match(line)
+    if area:
+        area_name = area[1]
+        bank_nr = int(area[2])
+    slack = slack_re.match(line)
+    if slack:
+        used = SIZE[area_name] - int(slack[1], 16)
+        print("%5s:%2d %04x/%04x (%.1f%%)" % (area_name, bank_nr, used, SIZE[area_name], used * 100 / SIZE[area_name]))