add get_pkg_config, work on README

Author: mattip

README.md

@@ -1,12 +1,33 @@
-# Building OpenBLAS
+# OpenBLAS
 
-This is a repository to trigger builds of OpenBLAS on Travis-CI (for aarch64,
-ppc64, s390x) and github actions for all the others.
+We build OpenBLAS on Travis-CI (for linux aarch64, ppc64, s390x) and github actions
+for linux, windows, macOS x86_64 and macOS arm64.
 
-The OpenBLAS libraries get uploaded to
+Tarballs are at
 https://anaconda.org/scientific-python-nightly-wheels/openblas-libs/files
 
-A project using these libraries, for Manylinux or macOS, will need the
+A project using the tarball, for Manylinux or macOS, will need the
 ``gfortran-install`` submodule used here, from
 https://github.com/MacPython/gfortran-install
 
+We also build and upload a pip-installable wheel. The wheel is self-contianed,
+no additional fortran support installations are needed. The wheel supplies
+interfaces for building and using OpenBLAS in a python project like SciPy or
+NumPy:
+
+## Buildtime
+
+- `get_include_dir()`, `get_lib_dir()` and `get_library()` for use in compiler
+  or project arguments
+- `get_pkg_config()` will return a multi-line text that can be saved into a
+  file and used with pkg-config for build systems like meson. This works around
+  the problem of [relocatable pkg-config
+  files](https://docs.conan.io/en/1.43/integrations/build_system/pkg_config_pc_files.html)
+  since the windows build uses pkgconfiglite v0.28 which does not support
+  `--define-prefix`.
+
+## Runtime
+
+- `open_so()` will load openblas into the executable and provide the openblas
+  symbols linked in from the `get_include_dir()` includes (on windows linking
+  with `get_lib_dir()`/`get_libarary()` is required).

local/openblas/__init__.py

@@ -1,10 +1,12 @@
 from pathlib import Path
 
 from . import _init_openblas
+from textwrap import dedent
 
 
 _HERE = Path(__file__).resolve().parent
 
+__all__ = ["get_include_dir", "get_lib_dir", "get_library", "get_pkg_config"]
 
 # Use importlib.metadata to single-source the version
 
@@ -34,3 +36,20 @@ def get_lib_dir():
 
 def get_library():
     return "openblas_python"
+
+def get_pkg_config():
+    return f"""\
+        libdir={_HERE}/lib
+        includedir={_HERE}/include
+        openblas_config= USE_64BITINT= DYNAMIC_ARCH=1 DYNAMIC_OLDER= NO_CBLAS= NO_LAPACK= NO_LAPACKE= NO_AFFINITY=1 USE_OPENMP= PRESCOTT MAX_THREADS=24
+        version=0.3.23
+        extralib=-lm -lpthread -lgfortran -lm -lpthread -lgfortran
+        Name: openblas
+        Description: OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version
+        Version: ${version}
+        URL: https://github.com/xianyi/OpenBLAS
+        Libs: -L${libdir} -lopenblas
+        Libs.private: ${extralib}
+        Cflags: -I${includedir}
+        """
+

pyproject.toml

@@ -8,7 +8,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "openblas"
-version = "0.3.20"
+version = "0.3.23"
 requires-python = ">=3.7"
 description = "Provides OpenBLAS for python packaging"
 readme = "README.md"