dmath

dmath is a deterministic math library for game projects that running on standard mobile (Android/iOS) and desktop platforms (Windows/Linux/MacOS).

dmath is a drop-in replacement for the math library in C11, based on musl-libc v1.2.5 with modifications to ensure that all floating-point operations are deterministic across different platforms and compilers. Although musl-libc is primarily designed for Linux, dmath can be used on Windows and MacOS. pocketpy uses dmath as its math library when compiled with -DPK_ENABLE_DETERMINISM=ON.

Installation

First clone this repo recursively:

git clone --recursive https://github.com/pocketpy/dmath

Then add the following line to your CMakeLists.txt:

add_subdirectory(<path_to_dmath_repo>)

target_link_libraries(<your_target> dmath)

if(MSVC)
    # Force multiple definitions to be allowed in MSVC.
    target_link_options(<your_target> PRIVATE /FORCE:MULTIPLE)
endif()

Usage

// CMakeLists.txt will redirect <math.h> to "dmath/include/public/math.h".
// You don't need to modify your existing code.
#include <math.h>

#include <stdio.h>

int main(){

// You can check this macro to ensure that `dmath` is used.
#ifndef _DMATH_H
    abort();
#endif

    double x = log(10);
    printf("log(10) = %f\n", x);
    return 0;
}

Tested Platforms

We have tested dmath on the following platforms and configurations.

Job	OS	Arch	Compiler
build_ubuntu	Ubuntu 22.04	x86_64	gcc
			clang
build_ubuntu_multiarch	Ubuntu 22.04	x86	gcc
			clang
		aarch64	gcc
			clang
		armv7	gcc
			clang
build_macos	MacOS 14	x86_64	clang
build_win32	Windows 2022	x86_64	cl

References

https://box2d.org/posts/2024/08/determinism/

License

MIT License