SCHG How-to

Convert the Hivebrain 2005 disassembly to ASM68K

From Sonic Retro

(Original guide by Puto)

This guide covers converting your split disassembly from SNASM68K (the assembler) to a better, faster assembler known as ASM68K. This tutorial is also necesary if you want to work on a 64-bit OS without restarting on a new split.

The only thing that SNASM68K has that ASM68K doesn't seem to support, is the "align" directive, as well as negative cnops. The align issue can be fixed with a simple macro that can be placed above StartOfRom:

align macro
     cnop 0,\1

Next edit the line below in build.bat:

snasm68k.exe -emax 0 -p -o ae- s1comb.asm, s1built.bin

With this:

asm68k /o op+ /o os+ /o ow+ /o oz+ /o oaq+ /o osq+ /o omq+ /p /o ae- s1comb.asm, s1built.bin

And then in the source file itself replace this incorrect line in "SkipSecurity:":

		move	a6,usp	  ; set usp to $0

with the proper:

		move.l	a6,usp	  ; set usp to $0

to result in a perfectly assembled ROM, which assembles so quickly I can barely have time to see the window open.

Better yet, since this supports long filenames, I can then replace the include.exe directives (in the format of ; include=xxx) with proper "include" directives, which allows me to completely skip the creation of s1comb.asm! This is very useful, because it means when you get a compiling error, you'll no longer have to check the line in s1comb.asm, and then track the location to sonic1.asm.

In the source file, replace all instances of:

; include=

with the proper:

	include "

Ensure that you replace all instances of:




As such, this entire line becomes unneeded in build.bat:

include.exe sonic1.asm s1comb.asm

And the ASM68K line can be changed to assemble sonic1.asm directly.

Now, delete this files:

  • include.exe
  • s1comb.asm (if it exists)

That's it! Enjoy a faster build of your hack.

SCHG How-To Guide: Sonic the Hedgehog (16-bit)
Fixing Bugs
Fix Demo Playback | Fix a Race Condition with Pattern Load Cues | Fix the SEGA Sound | Display the Press Start Button Text | Fix the Level Select Menu | Fix the Hidden Points Bug | Fix Accidental Deletion of Scattered Rings | Fix Ring Timers | Fix the Walk-Jump Bug | Correct Drowning Bugs | Fix the Death Boundary Bug | Fix the Camera Follow Bug | Fix Song Restoration Bugs | Fix the HUD Blinking | Fix the Level Select Graphics Bug | Fix a remember sprite related bug
Changing Design Choices
Change Spike Behavior | Collide with Water After Being Hurt | Fix Special Stage Jumping Physics | Improve the Fade In\Fade Out Progression Routines | Fix Scattered Rings' Underwater Physics | Remove the Speed Cap | Port the REV01 Background Effects | Port Sonic 2's Level Art Loader | Retain Rings Between Acts | Add Sonic 2 (Simon Wai Prototype) Level Select | Improve ObjectMove Subroutines | Port Sonic 2 Level Select
Adding Features
Add Spin Dash ( Part 1 / Part 2 / Part 3 / Part 4 ) | Add Eggman Monitor | Add Super Sonic | Add the Air Roll
Sound Features
Expand the Sound Index | Play Different Songs Per Act | Port Sonic 2 Final Sound Driver | Port Sonic 3's Sound Driver | Port Flamewing's Sonic 3 & Knuckles Sound Driver | Change The SEGA Sound
Extending the Game
Load Chunks From ROM | Add Extra Characters | Make an Alternative Title Screen | Use Dynamic Tilesets | Make GHZ Load Alternate Art | Make Ending Load Alternate Art | Add a New Zone | Set Up the Goggle Monitor | Add New Moves | Add a Dynamic Collision System | Dynamic Special Stage Walls System | Extend Sprite Mappings and Art Limit | Enigma Credits | Use Dynamic Palettes
Convert the Hivebrain 2005 Disassembly to ASM68K
Split Disassembly Guides
Set Up a Split Disassembly | Basic Level Editing | Basic Art Editing | Basic ASM Editing (Spin Dash)