softfloat and softposit in Python
* support for softfloat float16, float32, and float64
* support for softposit posit8, quire8, posit16, and quire16
-
+
## Demo
```
->>> import sfpy
->>> sfpy.Float32(1.3) + sfpy.Float32(1.4) # <-- construct from doubles
-Float32(2.6999998092651367)
->>> sfpy.Float32(3) # <-- construct from raw bits
-Float32(4.203895392974451e-45)
->>> sfpy.Float32(3).bits
-3
->>> x = sfpy.Float16(0)
->>> x
-Float16(0.0)
->>> x += sfpy.Float16(10.0) # <-- in-place operators have better performance
->>> x
-Float16(10.0)
->>> sfpy.Posit16(1.3) + sfpy.Posit16(1.4) # <-- posits work the same way as floats
-Posit16(2.7001953125)
->>> q = sfpy.Quire16(0) # <-- quire is also supported
->>> q
-Quire16(0.0)
->>> q.iqma(sfpy.Posit16(3), sfpy.Posit16(5))
->>> q
-Quire16(3.725290298461914e-09)
->>> q.iqma(sfpy.Posit16(3.0), sfpy.Posit16(5.0))
->>> q
-Quire16(15.0)
->>> q.bits
-1080863910568919232
->>> bin(q.bits)
-'0b111100000000000000000000000000000000000000000000000011000000'
-```
-
-## Building (on Linux)
-The Cython module can be built in place in the usual way:
-
-`python setup.py build_ext --inplace`
-
-This requires the submodules to be checked out, and the static libraries `SoftPosit/build/Linux-x86_64-GCC/softposit.a` and `berkeley-softfloat-3/build/Linux-x86_64-GCC/softfloat.a` to be built. Note that in order for Cython to be able to build the shared objects for the module, the static libraries must be compiled with -fPIC, which currently requires modifying the appropriate Makefiles manually. SoftPosit can be build with -fPIC using its python2 and python3 targets.
-
-The package can also be installed to a local Python distribution with pip, i.e. `pip install .` from the top level of the repository using the appropriate pip. This requires that Cython be installed.
+# WIP
+```
+
+## Building (on Linux x86_64, with bash)
+
+### Python Environment
+First, make sure a virtual environment is set up with Cython and twine:
+
+```
+$ python -m venv .env
+$ source .env/bin/activate
+(.env) $ pip install --upgrade -r requirements.txt
+[...]
+(.env) $
+```
+
+### Cython extensions
+Compile the Cython extensions to C:
+
+```
+(.env) $ cython sfpy/*.pyx
+(.env) $
+```
+
+### Static libraries
+The extension module depends on the softposit and softfloat static libraries.
+They can be built with the following:
+
+```
+(.env) $ (cd SoftPosit/build/Linux-x86_64-GCC/; make clean; make)
+[...]
+(.env) $ (cd berkeley-softfloat-3/build/Linux-x86_64-GCC/; make clean; make)
+[...]
+(.env) $
+```
+
+Note that some changes are needed to the Makefiles so that the libraries are
+compiled with the correct options. Both libraries need to use -fPIC, and
+SoftPosit may need -std=c99 to work on older versions of GCC. See the
+diff below.
+
+### Building locally
+The extension modules can be built in place in the usual way:
+
+```
+(.env) $ python setup.py build_ext --inplace
+[...]
+(.env) $
+```
+
+A local wheel (compatible with the python version installed in the virtual
+environment) can be built with the following:
+
+```
+(.env) $ python setup.py bdist_wheel
+[...]
+(.env) $
+```
+
+The local wheel will be created in the `dist/` directory. This is the recommended
+way to install the package when building it from source locally:
+
+```
+$ pip install dist/sfpy*.whl
+[...]
+$ python
+>>> from sfpy import *
+>>> Posit8(1.3)
+Posit8(1.3125)
+>>>
+```
+
+### Building manylinux1 wheels for distribution
+Widely compatible linux wheels can be built with the help of PyPA's manylinux
+docker image. This requires that Docker is installed, and that the host can pull
+the proper docker image.
+
+To build the manylinux wheels, run:
+
+```
+$ sudo docker run -u $(id -u) --rm -v `pwd`:/io quay.io/pypa/manylinux1_x86_64 /io/docker-build-wheels.sh
+[...]
+$
+```
+
+This will create a set of manylinux1 wheel files in the `wheelhouse/` directory.
+
+The docker build will make its own static libraries as part of the build process,
+and delete any existing static libraries with `make clean`.
+
+The wheels can be uploaded to PyPI (if you're the package maintainer) with
+
+```
+(.env) $ twine upload --repository-url https://test.pypi.org/legacy/ wheelhouse/*
+[...]
+(.env) $
+```
+
+to test on test PyPI, or
+
+```
+(.env) $ twine upload wheelhouse/*
+[...]
+(.env) $
+```
+
+for a release.
+
+### Makefile customizations
+The Makefiles used to build the static libraries need a few small tweaks to
+make sure that all the right flags are given to gcc. The changes are shown
+in the following diffs.
+
+`SoftPosit/build/Linux-x86_64/Makefile`
+
+```diff
+diff --git a/build/Linux-x86_64-GCC/Makefile b/build/Linux-x86_64-GCC/Makefile
+index 4409e43..46bb877 100644
+--- a/build/Linux-x86_64-GCC/Makefile
++++ b/build/Linux-x86_64-GCC/Makefile
+@@ -60,9 +60,9 @@ LINK_PYTHON = \
+
+ DELETE = rm -f
+ C_INCLUDES = -I. -I$(SOURCE_DIR)/$(SPECIALIZE_TYPE) -I$(SOURCE_DIR)/include
+-OPTIMISATION = -march=core-avx2 -O2
++OPTIMISATION = -fPIC -O2 ^M
+ COMPILE_C = \
+- gcc -c -Werror-implicit-function-declaration -DSOFTPOSIT_FAST_INT64 \
++ gcc -std=c99 -c -Werror-implicit-function-declaration -DSOFTPOSIT_FAST_INT64 \^M
+ $(SOFTPOSIT_OPTS) $(C_INCLUDES) $(OPTIMISATION) \
+ -o $@
+ MAKELIB = ar crs $@
+```
+
+`berkeley-softfloat-3/build/Linux-x86_64/Makefile`
+
+```diff
+diff --git a/build/Linux-x86_64-GCC/Makefile b/build/Linux-x86_64-GCC/Makefile
+index 2ee5dad..b175964 100644
+--- a/build/Linux-x86_64-GCC/Makefile
++++ b/build/Linux-x86_64-GCC/Makefile
+@@ -45,7 +45,7 @@ DELETE = rm -f
+ C_INCLUDES = -I. -I$(SOURCE_DIR)/$(SPECIALIZE_TYPE) -I$(SOURCE_DIR)/include
+ COMPILE_C = \
+ gcc -c -Werror-implicit-function-declaration -DSOFTFLOAT_FAST_INT64 \
+- $(SOFTFLOAT_OPTS) $(C_INCLUDES) -O2 -o $@
++ $(SOFTFLOAT_OPTS) $(C_INCLUDES) -O2 -fPIC -o $@
+ MAKELIB = ar crs $@
+
+ OBJ = .o
+```
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