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+# OpenLibm
+
+[![codecov](https://codecov.io/gh/JuliaMath/openlibm/graph/badge.svg?token=eTAdN7d9cg)](https://codecov.io/gh/JuliaMath/openlibm)
+
+[OpenLibm](https://openlibm.org/) is an effort to have a high quality, portable, standalone
+C mathematical library ([`libm`](http://en.wikipedia.org/wiki/libm)).
+It can be used standalone in applications and programming language
+implementations.
+
+The project was born out of a need to have a good `libm` for the
+[Julia programming language](http://www.julialang.org) that worked
+consistently across compilers and operating systems, and in 32-bit and
+64-bit environments.
+
+## Platform support
+
+OpenLibm builds on Linux, macOS, Windows, FreeBSD, OpenBSD, NetBSD, and
+DragonFly BSD.  It builds with both GCC and clang. Although largely
+tested and widely used on the x86 and x86-64 architectures, OpenLibm
+also supports arm, aarch64, ppc64le, mips, wasm32, riscv, s390(x) and
+loongarch64.
+
+## Build instructions
+
+### GNU Make
+
+1. Use GNU Make to build OpenLibm. This is `make` on most systems, but `gmake` on BSDs.
+2. Use `make USEGCC=1` to build with GCC. This is the default on
+   Linux and Windows.
+3. Use `make USECLANG=1` to build with clang. This is the default on OS X, FreeBSD,
+   and OpenBSD.
+4. Use `make ARCH=wasm32` to build the wasm32 library with clang.
+5. Architectures are auto-detected. Use `make ARCH=i386` to force a
+   build for i386. Other supported architectures are i486, i586, and
+   i686. GCC 4.8 is the minimum requirement for correct codegen on
+   older 32-bit architectures.
+
+
+**Cross Build**
+Take `riscv64` as example:
+1. install `qemu-riscv64-static`, `gcc-riscv64-linux-gnu`
+2. Cross build:
+```sh
+ARCH=riscv64
+TRIPLE=$ARCH-linux-gnu
+make ARCH=$ARCH TOOLPREFIX=$TRIPLE-  -j
+make -C test ARCH=$ARCH TOOLPREFIX=$TRIPLE-  -j
+```
+
+3. Run test with qemu:
+```sh
+qemu-$ARCH-static -L . -L /usr/$TRIPLE/  test/test-float
+qemu-$ARCH-static -L . -L /usr/$TRIPLE/  test/test-double
+```
+
+
+### CMake
+
+1. Create build directory with `mkdir build` and navigate into it with `cd build`.
+2. Run CMake to configure project and generate native build system with `cmake /path/to/openlibm/`
+or generate project with build system of choice e.g. `cmake /path/to/openlib/ -G "MinGW Makefiles"`.
+3. Build with the build system with `cmake --build .`.
+
+Default CMake configuration builds a shared library, this can easily be configured using
+[BUILD_SHARED_LIBS](https://cmake.org/cmake/help/latest/variable/BUILD_SHARED_LIBS.html)
+configuration option.
+
+
+## Acknowledgements
+
+PowerPC support for openlibm was graciously sponsored by IBM.