gblinez

Yet another Color Lines game. For Game Boy.

This replica features the same gameplay as the original version, with smooth animation.

How to Play

There is plenty of resources over the Internet, just Google the original title.

Key Bindings

Key	Function
D-Pad	Move the cursor
A	Select, or move the selected stone to the cursor
B	Hold for D-Pad auto-repeating (rapid mode)
Start	Restart the game

What's Next?

This would be the final release if nobody is interested in this project. I have currently no plan for implementing more features such as sound effects or high scores.

For Fellow Developers

You may find my own libraries in the src/dwlib80/ directory. (I know there is linker, just laziness.)

Many of the functions are properly documented, you can use the VS Code extension RGBDS Z80 for hovering tooltips.

Members start with a _ is considered private, they are not meant to be used by end users.

memory.asm

A must have for every program beyond "Hello, world!".

• memset
• memcpy
• reverse
• macro read - A one-liner for reading memory into any register.
• macro write - A one-liner for writing any register into memory.
• macro readh - Same as above, but optimized with ldh instruction.
• macro writeh - Same as above, but optimized with ldh instruction.

math.asm

Nothing here. No trig functions, floating-point arithmetics, nor even integer multiplying. Don't expect this as something like math.h in C.

• Divide - 8-bit general division algorithm.
• ToDecimal8 - 8-bit BCD.
• macro AddR16D8 - A handy macro for adding 8-bit immediate values to any register pair (using carry flag, not HL register).

rand.asm

For best performance, random numbers are not generated by RNG algorithms but a 256 bytes table with entropy provided by user inputs. To make the RNG unbiased, an other table is used.

You should call macro SeedRandom in your joypad interrupt handler to collect entropy.

animation.asm

Linear animation, with arguments of delta X, delta Y, and duration in frames.

The current implementation will block the execution until the animation is ended.

pathfinding.asm

A standard (?) BFS algorithm.

• 512 bytes WRAM is used for buffer.
• Requirements for a compatible gameboard:
  • Should be a byte[] array.
  • Less than 256 bytes.
  • Value 0 is passable, otherwise obstacles.

After a successful search, Pathfinding_backtrace is filled with directions from search target to search origin. If you want the reverse path, simply swap the origin and the target.

controlflow.asm

An elegant way to write counter loops.

Search BeginLoop in this repository for example.

oam.asm

All the OAM and DMA stuff goes here.

Sprites related functions are organized to 8x8, 8x16, 8x8x4, 8x16x2. Currently, only 8x16x2 functions are implemented.

• OAMBuffer - Don't allocate it yourself, just use this for your game.
• ClearOAMBuffer
• SetSprite - It should be called SetSpriteTile. (An afterthought.)
• SetSpritePos
• HideSprite - Set sprite pos away from screen area, technically.
• InitDMA - Copy DMA waiting routine to HRAM.
• StartDMA

input.asm

An input handler, with keypress support.

Call Input from your game loop, then read JoypadState and PressedKeys.