GBDK Programming Sample

In the previous post, we checked out GBDK Programming Setup. The GBDK is a cross-platform development kit for sm83, z80 and 6502 based gaming consoles including the Nintendo Game Boy and Game Boy Color.

Using the GBDK, it is now possible to write game code using the C language rather than pure Z80 assembly. Therefore, we would like to extend this knowledge and checkout some code samples and homebrew games.

Let's check it out!

Software
Follow all instructions from the previous post: this documents how to setup all the pre-requisite software.
Note: ensure you have downloaded and installed the GBDK devkit and Small Device C Compiler [SDCC].

Examples
As per the previous post, after the GBDK has been downloaded, installed and setup, we should now checkout C:\gbdk\examples\gb to learn more about APIs available in the devkit. Replicate prior Hello World example.

Launch Visual Studio 2015. File | New | Project... | Visual C++ | Win32 | Win32 Project

Name:	Game
Location:	C:\apa_image
Create directory for solution	UNCHECKED

Copy over all original folders and files from the corresponding example. Copy from prior Hello World example the hidden .vscode folder and files. Copy also build.bat and align with source compile.bat file. Add relevant files to Visual Studio 2015. Press Ctrl+1 to build, link and run code similar to the prior Hello World example!

Launch Visual Studio Code. Open example folder. Set breakpoint in main.c. Press F5 to debug step thru code


Here is the complete list:

CUSTOM: apa_image  SOURCE: apa_image  CUSTOM: banks  SOURCE: banks  CUSTOM: bcd  SOURCE: bcd  CUSTOM: colorbar  SOURCE: colorbar  CUSTOM: comm  SOURCE: comm  CUSTOM: crash  SOURCE: crash  CUSTOM: dscan  SOURCE: dscan  CUSTOM: filltest  SOURCE: filltest  CUSTOM: galaxy  SOURCE: galaxy  CUSTOM: gb-dtmf  SOURCE: gb-dtmf  CUSTOM: gbcompress  SOURCE: gbcompress  CUSTOM: incbin  SOURCE: incbin  CUSTOM: irq  SOURCE: irq  CUSTOM: isr_vector  SOURCE: isr_vector  CUSTOM: large_map  SOURCE: large_map  CUSTOM: lcd_isr_wob  SOURCE: lcd_isr_wob

CUSTOM: linkerfile  SOURCE: linkerfile  CUSTOM: metasprites  SOURCE: metasprites  CUSTOM: paint  SOURCE: paint  CUSTOM: ram_function  SOURCE: ram_function  CUSTOM: rand  SOURCE: rand  CUSTOM: rpn  SOURCE: rpn  CUSTOM: scroller  SOURCE: scroller  CUSTOM: sgb_border  SOURCE: sgb_border  CUSTOM: sgb_multiplay  SOURCE: sgb_multiplay  CUSTOM: sgb_pong  SOURCE: sgb_pong  CUSTOM: sgb_sfx  SOURCE: sgb_sfx  CUSTOM: simple_physics  SOURCE: simple_physics  CUSTOM: sound  SOURCE: sound  CUSTOM: temp_minimal  SOURCE: temp_minimal  CUSTOM: temp_subfolder  SOURCE: temp_subfolder  CUSTOM: wav_sample  SOURCE: wav_sample

Samples
Gaming Monsters YouTube channel has many samples to teach how to develop your own GameBoy games:

Launch Visual Studio 2015. File | New | Project... | Visual C++ | Win32 | Win32 Project

Name:	Game
Location:	C:\SimpleSprites
Create directory for solution	UNCHECKED

Copy over all original folders and files from the corresponding example. Copy from prior Hello World example the hidden .vscode folder and files. Copy also build.bat and align with source's make.bat file. Add relevant files to Visual Studio 2015. Press Ctrl+1 to build, link and run code similar to the prior Hello World example!

Launch Visual Studio Code. Open example folder. Set breakpoint in main.c. Press F5 to debug step thru code


Here is the complete list:

CUSTOM: helloworld  SOURCE: helloworld  CUSTOM: simplesprites  SOURCE: simplesprites  CUSTOM: movesprites  SOURCE: movesprites  CUSTOM: background  SOURCE: background  CUSTOM: window  SOURCE: window  CUSTOM: sound  SOURCE: sound  CUSTOM: noise  SOURCE: noise  CUSTOM: simplejumping  SOURCE: simplejumping  CUSTOM: metasprites  SOURCE: metasprites  CUSTOM: spritecollision  SOURCE: spritecollision  CUSTOM: bkgdcollision  SOURCE: bkgdcollision

CUSTOM: splashscreens  SOURCE: splashscreens  CUSTOM: fadeeffects  SOURCE: fadeeffects  CUSTOM: keyboard  SOURCE: keyboard  CUSTOM: savename  SOURCE: savename  CUSTOM: colorsprites  SOURCE: colorsprites  CUSTOM: backgrounds  SOURCE: backgrounds  CUSTOM: makingmusic  SOURCE: makingmusic  CUSTOM: spritetricks  SOURCE: spritetricks  CUSTOM: scrolling  SOURCE: scrolling  CUSTOM: debugging  SOURCE: debugging  CUSTOM: platformer  SOURCE: platformer

Homebrew
Larold's Jubilant Junkyard is a website/blog/shop which focuses on creating digital products including game development projects and tutorials. The Nintendo GameBoy development tutorial series is very educational.

Follow Larold's Jubilant Junkyard YouTube video channel for additional GBDK 2020 information and content:

SCREEN resolution	20 x 18 tiles	160 x 144 pixels
BACKGROUND	32 x 32 tiles	256 x 256 pixels

Compiler flags

-Wm-yc	GameBoy Color compatible	NB: lowercase c
-Wm-yC	GameBoy Color only	NB: uppercase C
-Wm-ys	Super GameBoy compatible

GameBoy Color Tile Attributes

Bit 7	priority flag	0: tiles below sprites, 1: tiles above sprites
Bit 6	vertical flip	0: tiles normal, 1: flipped vertically
Bit 5	horizontal flip	0: tiles normal, 1: flipped horizontally
Bit 4	not used
Bit 3	character bank specification	0: tiles at bank0, 1: tiles at bank1
Bit 2	see bit 0
Bit 1	see bit 0
Bit 0	bits 0-2	indicate tile color palette assignment

Launch Visual Studio 2015. File | New | Project... | Visual C++ | Win32 | Win32 Project

Name:	Game
Location:	C:\AlleywayGameboy
Create directory for solution	UNCHECKED

Copy over all original folders and files from the corresponding example. Copy from prior Hello World example the hidden .vscode folder and files. Copy also build.bat and align with source's make.bat file. Add relevant files to Visual Studio 2015. Press Ctrl+1 to build, link and run code similar to the prior Hello World example!


NOTE: ensure that the GBDK header files are included for Intellisense: Right click project | Properties |
Configuration Properties | C/C++ | General | Additional Include Directories | %GBDK_WIN%/include; $(SolutionDir)/headers/gen; $(SolutionDir)/headers/main; %(AdditionalIncludeDirectories).

Here is the complete list:

CUSTOM: alleyway  SOURCE: alleyway  CUSTOM: flappy-bird  SOURCE: flappy-bird

CUSTOM: pacman  SOURCE: pacman  CUSTOM: space-invaders  SOURCE: space-invaders

Summary
Armed with all this knowledge, we are now in an excellent position to build complete video games for the Nintendo Game Boy and Game Boy Color. In the interim, we see the GameBoy Competition 2023 is here!

GBDK Programming Setup

In 2017, we checked out devkitSMS Programming Setup to build 8-bit video games for Sega Master System. Here we installed all the tools required including a powerful emulator: Emulicious to test the video games.

Emulicious is a free multi-system emulator popular for Sega Master System and Sega Game Gear games but can also play Nintendo Game Boy and Game Boy Color games. Therefore, let's leverage Sega Master System development setup to build and test games for Nintendo Game Boy and Game Boy Color using the GBDK.

Let's check it out!

GDDK
The GBDK is a cross-platform development kit for sm83, z80 and 6502 based gaming consoles including the Nintendo Game Boy and Game Boy Color. It includes libraries, toolchain utilities and SDCC C compiler suite.

Software
Follow all instructions from the previous post: this documents how to setup the pre-requisite software.

Here is a summary of all required software to be installed:

Name  Version  C IDE Editor  Visual Studio 2015  C IDE Editor  Visual Studio Code  Cross compiler  Small Device C Compiler

Name  Version  Make files  Cygwin  Emulators  Emulicious, BGB  Debugger  Emulicious Debugger

Note: this post documents how to download and install SDCC v4.1.0 on both Windows and Linux.

GBDK
Navigate to the gbdk-2020 repository on github: gbdk-2020 has full instructions here. Download the latest release from gbdk-2020 archive e.g. gbdk-4.1.1 or git clone latest source code. Extract code into C:\gbdk.

Setup the following environment variable for GBDK_WIN as it can be useful throughout GBDK development. Add the following one environment variable: System | Advanced system settings | Environment Variables:

Variable	Value	Description
GBDK_WIN	C:\gbdk	Windows path format

Example
As an example, let's write a simple program that prints Hello World to the screen using the GameBoy DevKit. Create new directory: C:\HelloWorld. Create new file main.c. Copy in the following code to print Hello World.

main.c

#include <gb/gb.h>
#include <stdio.h>

void main()
{
	printf( "HELLO WORLD" );
}

Build
Manually compile and link the Hello World program. Launch command prompt: Start | Run | cmd.


Change directory cd C:\HelloWorld. Next, execute the following 2x commands (in bold):

ACTION	COMMAND	OUTPUT
Compile	%GBDK_WIN%/bin/lcc -Wa-l -Wl-m -Wl-j -c -o main.o main.c	main.o
Link	%GBDK_WIN%/bin/lcc -Wa-l -Wl-m -Wl-j -o output.gb main.o	output.gb

Finally, type output.gb. The Hello World program should launch in the Emulicious emulator.
Congratulations! You have just written your first test program using the GameBoy DevKit.

IMPORTANT
If game does not initially render correct then select Options menu | System | Game Boy or Game Boy Color.

Automate
Let's automate the build process: create C:\HelloWorld\build.bat script file that contains the commands:

@echo off
%GBDK_WIN%/bin/lcc -Wa-l -Wl-m -Wl-j -c -o main.o main.c
%GBDK_WIN%/bin/lcc -Wa-l -Wl-m -Wl-j -o output.gb main.o
output.gb

Visual Studio 2015
Similar to Sega Master System development using devkitSMS, setup Visual Studio 2015 as per instructions here. Also, follow instructions here to connect Ctrl+1 hot key to automatically compile, link and run code.

Launch Visual Studio 2015. File | New | Project... | Visual C++ | Win32 | Win32 Project

Name:	HelloWorld
Location:	C:\
Create directory for solution	UNCHECKED

Application type:	Console application
Additional options:	Empty project CHECKED

Navigate to C:\HelloWorld. Add existing: main.c and build.bat at the same folder level as HelloWorld.sln.


Finally, ensure that the GBDK header files are included for Intellisense: Right click project | Properties |
Configuration Properties | C/C++ | General | Additional Include Directories | %GBDK_WIN%/include.

Press Ctrl+1 to build, link and run!


Visual Studio Code
Similar to Sega Master System development using devkitSMS, setup Visual Studio Code as per instructions here. Add hidden .vscode folder + include tasks.json and launch.json files beneath to build + debug code.

Launch Visual Studio Code. Open folder C:\HelloWorld. Add the .vscode folder the following files beneath:

c_cpp_properties.json

{
  "configurations": [
    {
      "name": "stevepro",
      "intelliSenseMode": "clang-x64",
      "includePath": [
        "${env:GBDK_WIN}/include"
      ],
      "cStandard": "c11",
      "cppStandard": "c++17",
      "browse": {
        "path": [
          "${workspaceFolder}"
        ],
        "limitSymbolsToIncludedHeaders": true,
        "databaseFilename": ""
      }
    }
  ],
  "version": 4
}

tasks.json

{
    "version": "2.0.0",
    "label": "build",
    "type": "shell",
    "windows": {
        "command": "./build.bat"
      },
    "presentation": {"echo": true, "reveal": "always", "focus": false, "panel": "shared", "showReuseMessage": false, "clear": true},
    "group": {"kind": "build", "isDefault": true},
}

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "emulicious-debugger",
            "request": "launch",
            "name": "Launch in Emulicious",
            "program": "${workspaceFolder}/output.gb",
            "port": 58870,
            "stopOnEntry": false,
        }
    ]
}

Open main.c. Set breakpoint. Press Ctrl + Shift + B to build source code. Press F5 to debug step thru code:


In Emulicious, choose Tools menu | Debugger to be able to fully debug step thru the Z80 assembly code:


Summary
Now the GBDK has been downloaded, installed and setup, we should checkout C:\gbdk\examples\gb to learn more about the APIs available in the devkit + checkout some code samples and complete homebrew games. This will be the topic of the next post.

eBPF Programming Sample

In the previous post, we checked out eBPF Programming Setup. Extended Berkeley Packet Filter [eBPF] is technology that runs sandboxed programs in privileged context like the OS kernel to safely and efficiently extend the capabilities of the kernel at runtime without requiring changes to the kernel source code. One issue is there are currently limited methods to debug BPF programs thus we'd like to explore test options.

Let's check it out!

Software
Follow all instructions from the previous post to install CLion and VS Code on Ubuntu Linux. Also install the following components for low level C code unit testing, mocking and integration: Unity, CMock, Ceedling.

Unity	Unit testing framework built for C projects with a focus on working with embedded toolchains
CMock	Mock and stub generator and runtime for unit testing C designed to work smoothly with Unity
Ceedling	Build system for C projects using Ruby Rake [make] build system to integrate Unity + CMock

Pre-requisites
As above, Ceedling requires Ruby installed otherwise sudo: gem: command not found errors may be thrown. Also, CMock requires Ruby bundle be installed otherwise Command 'bundle' not found errors may be thrown.

sudo apt install ruby

sudo apt install ruby-bundler

Unity
Unity is a unit testing framework built for C, with a focus on working with embedded toolchains, which we would like to try and leverage for BPF development. Follow instructions here to install and configure Unity.

git clone git@github.com:ThrowTheSwitch/Unity.git  cd Unity  cmake .  make  sudo make install  sudo cp libunity.a /usr/local/lib  sudo cp src/unity*.h /usr/local/include/unity

CMock
CMock is a mock and stub generator designed to work smoothly with Unity. CMock automagically parses the C headers and creates useful mock interfaces used for unit testing. Follow instructions here to install CMock.

git clone --recursive https://github.com/throwtheswitch/cmock.git  cd cmock  bundle install

Ceedling
Ceedling is a build system for C projects using Ruby Rake [make] build system. Ceedling also makes TDD Test Driven Development simple by integrating CMock + Unity. Follow instructions here to install Ceedling.

ruby -v  sudo gem install ceedling

Hello Unity
In the previous post, examples installed the libbpf C-based library. Therefore, extend an example and write tests that invoke simple libbpf APIs, for example, libbpf_num_possible_cpus directly using Unity framework.

Launch CLion | New Project | C Executable | Location: /home/stevepro/HelloUnity | Language std: C11

Create

Organize src and test directory structure. Install libbpf beneath src folder. Rename main.c to all_tests.c and move beneath test folder. Update all prod and unit test code. Complete CMakeLists.txt to include library files:

cmake_minimum_required(VERSION 3.19)  project(HelloUnity C)  set(CMAKE_C_STANDARD 11)    include_directories(src/ /usr/local/include/unity/ src/include/libbpf/src)  link_directories(/usr/local/lib/ src/include/libbpf/src/amd64)    file(GLOB CODE_FILES src/*.c)  file(GLOB TEST_FILES test/*.c)  add_executable(HelloUnity ${CODE_FILES} ${TEST_FILES} )  target_link_libraries(HelloUnity unity bpf elf z)

Edit configurations | Run with root privileges | Set breakpoints | Press F5 to debug step thru source code.



Hello CMock
At the time of writing, there is currently no way to debug BPF programs' source code interactively. Therefore, we would like to attempt to mock BPF programs or at least underlying C sourc code somehow using CMock.

Follow the example Spin up CMock. This article uses Ceedling to automate project setup and generate mocks but we will complete the following manually first to better understand the process. Original code found here.

Open folder /home/stevepro/HelloCMock. Copy inc/rectangle.h + project.yml. Execute mock command:

ruby ~/GitHub/ThrowTheSwitch/cmock/lib/cmock.rb -oproject.yml inc/rectangle.h

This creates mocks folder two corresponding files: mock_rectangle.h and mock_rectangle.c. Notice we did not attempt to use CLion as is not currently integrated; any attempt may produce Multiple Definition issue!


Hello Ceedling
Complete previous example but this time try Ceedling using the article as a guideline: Launch the Terminal:

cd $HOME  ceedling new HelloCeedling

Copy all project files into src and test directories. Include inc and update project.yml with the inc directory:

  :paths:
  :test:
    - +:test/**
    - -:test/support
  :source:
    - src/**
  :include:
    - inc/**
  :support:
    - test/support
  :libraries: []

Run tests manually simply by typing ceedling

Debug tests interactively with GDB as follows: Launch VS Code. Press F5 to add launch.json file to complete:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "ceedling_gdb",
            "type": "cppdbg",
            "request": "launch",
            "program": "${workspaceFolder}/build/test/out/test_shape_container.out",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceFolder}",
            "environment": [],
            "externalConsole": true,
            "MIMode": "gdb",
            "miDebuggerPath": "/usr/bin/gdb",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ]
        }
    ]
}

Set breakpoint in test_shape_container.c | Press F5 to debug step thru source code:



Summary
According to ChatGPT, eBPF is versatile technology that allows safe and efficient code execution within the Linux kernel without requiring modification of kernel code. This feature makes it attractive for applications including network packet filtering, security, logging + tracing, monitoring, and performance optimization.

In summary, while eBPF is a valuable addition to the Linux ecosystem, it is not expected to replace kernel development. Instead, eBPF complements this by currently providing a flexible and efficient way to extend specific kernel features. Therefore, it will be interesting to see if this technology is dominant in the future.

eBPF Programming Setup

Extended Berkeley Packet Filter [eBPF] is a technology that runs sandboxed programs in privileged context like the OS kernel to safely and efficiently extend the capabilities of the kernel at runtime without requiring changes to the kernel source code. libbpf is a C-based library that takes compiled BPF object files and loads and verifies them into the kernel attachiing BPF programs to various kernel hooks and execute custom code.

Let's check it out!

Software
Follow all instructions from the previous post to install CLion and VS Code on Ubuntu Linux. Also install the bpftool which was added to the 2017 Linux kernel as a user space utility to introspect the eBPF subsystem.

git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  cd linux  cd tools/bpf/bpftool  make  sudo make install  bpftool version

Alternatively, download bpftool binary from the Github releases and extract into /usr/local/bin directory.

Hello World
Create your first BPF program using this simple eBPF CO-RE application as a reference however using CLion. Launch CLion | New Project | C Executable | Location: /home/stevepro/HelloWorld | Language std: C11

Create

A new C project will be created which automatically adds the following two files: main.c and CMakeLists.txt

main.c	CMakeLists.txt
#include <stdio.h>  int main()  {   printf( "Hello, World!\n" );   return 0;  }	cmake_minimum_required(VERSION 3.19)  project(HelloWorld C)    set(CMAKE_C_STANDARD 11)    add_executable(HelloWorld main.c)

In the Terminal window within CLion IDE enter the following commands to install and buld the libbpf library:

git clone https://github.com/libbpf/libbpf  cd libbpf/src  make  sudo make install  cd ../..

Next, enter commands to create the vmlinux.h file. Create and build the Hello BPF program + skeleton file:

bpftool btf dump file /sys/kernel/btf/vmlinux format c > vmlinux.h  touch hello.bpf.c  clang -g -O2 -target bpf -D__TARGET_ARCH_x86_64 -I libbpf/src -c hello.bpf.c -o hello.bpf.o  bpftool gen skeleton hello.bpf.o > hello.skel.h

hello.bpf.c	CMakeLists.txt
#include "vmlinux.h"  #include "bpf_helpers.h"    SEC("tracepoint/syscalls/sys_enter_execve")  int hello_bpf(struct trace_event_raw_sys_enter *ctx)  {   bpf_printk("Hello world!\n");   return 0;  }  char LICENSE[] SEC("license") = "GPL";	cmake_minimum_required(VERSION 3.19)  project(HelloWorld C)    set(CMAKE_C_STANDARD 11)    include_directories(.)  link_directories(libbpf libbpf/src)    add_executable(HelloWorld main.c)  target_link_libraries(HelloWorld bpf elf z)

Rename main.c to hello.c and update the driver program code. Edit configurations | Run with root privileges

Set break point in hello.c | HelloWorld | Debug or Press F5 to launch your first Hello World BPF program!

IMPORTANT you can tail BPF output in Terminal window: sudo cat /sys/kernel/debug/tracing/trace_pipe

Hello Maps
BPF maps are generic structures for storing different types of data accessible between kernel + user space. Launch CLion | New Project | C Executable | Location: /home/stevepro/HelloMaps | Language std: C11

Create

Repeat the process similar to Hello World: Install the libbpf library. Create the vmlinux header file, the Maps BPF program and driver code. Compile code. Update the CMakeLists build script and Run with root privileges:


libbpf-bootstrap
libbpf-bootstrap provides a starting point for building your own BPF applications with things like BPF Compile Once-Run Everywhere [CO-RE] and vmlinux.h. Numerous more BPF samples can be found at the Linux repo.

CUSTOM: minimal  SOURCE: minimal  CUSTOM: minimal_ns  SOURCE: minimal_ns  CUSTOM: minimal_legacy  SOURCE: minimal_legacy  CUSTOM: bootstrap  SOURCE: bootstrap  CUSTOM: uprobe  SOURCE: uprobe  CUSTOM: usdt  SOURCE: usdt

CUSTOM: fentry  SOURCE: fentry  CUSTOM: kprobe  SOURCE: kprobe  CUSTOM: ksyscall  SOURCE: ksyscall  CUSTOM: tc  SOURCE: tc  CUSTOM: profile  SOURCE: profile  CUSTOM: sockfilter  SOURCE: sockfilter

Summary
Although libbpf allows BPF programs to be loaded, verified and attached to various kernel hooks and execute custom code there is currently no way to debug BPF programs' source code interactively. Therefore, this now presents alternatives to explore unit testing and mock BPF programs. This will be the topic of the next post.

Sega Console Game Port

In 2017, we checked out devkitSMS Programming Setup to build code in C for the 8-bit Sega Master System. Then, in 2020, we checked out SGDK Programming Setup to build code in C for the 16-bit Sega Mega Drive.

Leveraging this knowledge, we would now like to port existing code built for the 8-bit Sega Master System, for example, Simpsons Trivia SMS to the 16-bit Mega Drive Simpsons Trivia MD and document the process.

SEGA MASTER SYSTEM [256 x 192]	SEGA MEGA DRIVE [320 x 224]

Let's check it out!

Software
Follow most instructions from the previous post: this documents how to setup some pre-requisite software.

Here is a summary of some of the software to be installed:

Name  Version  C IDE Editor  Visual Studio 2015  Emulators  Fusion, Gens KMod

Name  Version  Cross compiler  GCC  Make files  Cygwin

Setup Project
Create folder C:\SimpsonsTriviaMD. Copy new SGDK custom library lib folder here. Create sub-folder: dev. Change directory to dev folder and create the following sub-folders as indicated per Usage: inc, out, res, src


Launch Visual Studio 2015. File | New | Project... | Visual C++ | Win32 | Win32 Project

Name:	Game
Location:	C:\SimpsonsTriviaMD\dev
Create directory for solution	UNCHECKED

OK

Application type:	Console application
Additional options:	Empty project CHECKED

Finish

First, remove x64 build configuration! Right click Solution | Properties. Click Configuration Manager button. Click Active solution platform drop down | Edit. Click x64 option | Remove. Now will have only Win32 build.

Right click Project | Properties | Configuration Properties | General. Set Output and Intermediate directories:

Output Directory:	$(SolutionDir)..\bin\$(ConfigurationName)
Intermediate Directory:	$(SolutionDir)..\obj\$(ConfigurationName)

Right click Project | Properties | Configuration Properties | C++ | General. Set Additional Include Directories:

Value:

$(SolutionDir)..\lib;$(ProjectDir)inc;$(ProjectDir)res;$(GDK_WIN)\inc;$(IncludePath)

Right click Project | Properties | Configuration Properties | Linker | General | Additional Library Directories:

Value:

$(SolutionDir)..\lib

Right click Project | Properties | Configuration Properties | Linker | Input. Set the Additional Dependencies:

Value:

_genesis.lib;%(AdditionalDependencies)

The final solution should look like this:


Setup Resources
Import all resources into your project as media files that your game will use such as images for background tiles + sprites, audio for music + sound effects etc. Clone the "Setup Project" folder and follow these steps:

Change directory to res folder under dev folder. Copy all resources here. Create corresponding *.res files. Next execute build.bat to compile all resources then generate all corresponding gfx and sfx header files.

Create folder gfx at same level as dev folder. Create sub folder res. Add dummy corresponding translation unit files under res sub folder. Repeat process with sfx folder. Import all translation units into Visual Studio.


Setup Folders
Larger game projects will require nested folders in the inc or src directories to organize engine and screen code etc. Clone the "Setup Resources" folder and add all necessary subfolders + then update the makefile.

Launch Visual Studio and include resource files as before. Next, scale out engine and screen code but now organize into subfolders. Create as New Filters under Visual Studio Header Files and Source Files solution:

Create corresponding engine and screen subfolders beneath inc folder under dev. Add header files. Create engine and screen subfolders beneath src folder under dev. Add all the corresponding translation unit code.

Right click Project | Properties | Configuration Properties | C++ | General. Set Additional Include Directories:

Value:

$(SolutionDir)..\lib;$(ProjectDir)inc;$(ProjectDir)res;$(GDK_WIN)\inc;$(IncludePath);  $(ProjectDir)inc\engine;$(ProjectDir)inc\object;$(ProjectDir)inc\screen

Customize the makefile.gen file to include the new subfolders accordingly. Copy %GDK_WIN%\makefile.gen to local dev folder. Update makefile: Add new $(wildcard $(SRC)/ and -I$(INCLUDE) entries per folder.

Update dev built.bat file to use new local custom makefile.gen instead of de-facto %GDK_WIN% version.
If you remove pre-build step to speed up makefile build then don't forget to create out subfolders manually.


Convert APIs
Finally, copy over all engine, object, screen etc. files from the Sega Master System code base into the Sega Mega Drive port. Convert all devkitSMS APIs to the SGDK equivalents. Allow for different screen resolution!

Here is quick cheat of devkitSMS to SGDK API conversions; of course not all APIs are one-to-one mapping:

	SEGA MASTER SYSTEM	SEGA MEGA DRIVE
Audio	PSGPlay();  PSGStop();  PSGGetStatus();	XGM_startPlayPCM();  XGM_stopPlayPCM();  XGM_isPlayingPCM();
Dimensions	256 x 192 [32x24]	320 x 224 [40x28]
Font	SMS_setNextTileatXY();  SMS_setTile();	VDP_setMapEx();
Graphics	SMS_loadPSGaidencompressedTiles();  SMS_loadBGPalette();	VDP_drawImageEx();  VDP_setPalette();
Hack	Address : 0x0050	Address : 0x01E0
Input	SMS_getKeysStatus();	JOY_readJoypad();
Random	rand();	random();
Sprites	SMS_addSprite();  SMS_copySpritestoSAT();	SPR_addSprite();  SPR_update();

Summary
Repeat process with Skazka. In summary, the Master System to Mega Drive port should be fairly seemless J

SEGA MASTER SYSTEM [256 x 192]	SEGA MEGA DRIVE [320 x 224]