Chip 8

This crate aims to provide platform agnostic implementation of Chip-8 interpreter.

There are alot of extensions existing for Chip-8 platform, however this crate will provide only the most common 35 instruction from Super-Chip specification from 1991, without the additional opcodes that provide extended functionality.

Fully qualified emulator should consist of following peripherals:

• sound sink (most commonly a buzzer)
• 64x32 px display
• 4x4 matrix keyboard

No std

Peach8 is fully compatible with no_std environment. To overcome the differences between different embedded platforms, the user is provided with a Context trait, which should handle:

• displaying frame on the screen,
• getting user input,
• generating random numbers,
• turning sound on and off,

Implementation guidelines

There are two main methods that progresses emulation:

• Peach8::tick_chip
• Peach8::tick_timers

Both of them should be tacted independly. tick_timers should be called with 60Hz frequency, and tick_chip should be called with around 500Hz frequency.

Emulation cycle (tick_chip) is as follows:

• Get input (Context::get_keys),
• Execute next instruction,
• Draw to the screen (Context::on_frame),

Timers cycle (tick_timers) is as follows:

• Decrement active timers (sound and delay),
• Call Context::sound_on or Context::sound_off when appropriate,

Thread safety

Although most no_std targets are single-threaded, the interrupts may lead to the same problems that are encountered in multi-threading.

Peach8 can handle thread-safety on targets, where there is a support for atomic operations on u8. This is handled by atomic feature, enabled by default. On platforms where there is no such support, eg. thumbv6em-none-eabi, implementation should ensure that those methods won`t interrupt eachother.

Implementation of Context trait also have to be Sync for Peach8 to be sync.

Examples:

coming soon...