implementation of the Gameboy apu in ~1k lines of code.
this uses blip_buf internally to resample the psg channels to your desired output rate.
when using this library, you have the choice between using blip_buf or Blip_buffer, the latter being c++.
using the latter will allow you to have bass and treble control, as well as sounding slightly better sounds slightly better. Other than that, both function the same and the api remains the same, and the exposed api doesn't change.
The C version compiles down to ~25 KiB in release mode.
The CXX version compiles down to ~34 KiB in release mode.
gb_apu passes all of blarggs dmg_sound and cgb_sound tests and all audio tests in numism.
The level of accurary does depend on your emulation of the Gameboy timer. For example, the apu_frame_sequencer_clock() should be called on the falling edge (bit goes from 1 -> 0) of bit 4 of DIV. In double speed mode, this is the falling edge of bit 5. Be aware that DIV can be written to which sets DIV to 0, which could cause an early clock, or, result in no clocks if DIV is written to frequently.
gb_apu currently doesn't accurately emulate "zombie mode". Basic emulation of it exists, and can be enabled with -DGB_APU_ZOMBIE=ON.
first you need to choose between the C and CPP version. The exposed api is written in C, so as long as you have a CPP compiler, you should chose that version.
Please give credit if using any of this code To add this to your project, add the following files depending on your language of choice:
- gb_apu.c
- blip_wrap.c
- blip_buf.c
- gb_apu.c
- blip_wrap.cpp
- Blip_Buffer.cpp
you can also use the included cmake file:
set(GB_APU_CXX OFF) # set ON if wanting Blip_Buffer
set(GB_APU_ZOMBIE OFF) # set ON for zombie mode emulation
add_subdirectory(gb_apu)
target_link_libraries(your_exe PRIVATE gb_apu)or use cmake's fetch content:
include(FetchContent)
FetchContent_Declare(gb_apu
GIT_REPOSITORY https://github.com/ITotalJustice/gb_apu.git
GIT_TAG v1.2.0
)
set(GB_APU_CXX OFF) # set ON if wanting Blip_Buffer
set(GB_APU_ZOMBIE OFF) # set ON for zombie mode emulation
FetchContent_MakeAvailable(gb_apu)
target_link_libraries(your_exe PRIVATE gb_apu)- gb_apu is licenced under MIT.
- blip_buf and Blip_Buffer are licenced under LGPL.
If you cannot use gpl code in your project, create a blip_wrap.c/cpp file with your own bandlimited synthesis code, or remove all blip_wrap_ functions from gb_apu.c and sample the channels however you wish.