OCCA

OCCA is an open-source (MIT license) library used to program current multi-core/many-core architectures. Devices (such as CPUs, GPUs, Intel's Xeon Phi, FPGAs, etc) are abstracted using an offload-model for application development and programming for the devices is done through a C-based (OKL) or Fortran-based kernel language (OFL). OCCA gives developers the ability to target devices at run-time by using run-time compilation for device kernels.

README

Installing

Using a terminal, go to your OCCA directory You should see: README.md (this file) include src lib

To compile libocca.so, type:

make

To compile the Fortran library, setup the OCCA_FORTRAN_ENABLED environment variable before compiling

export OCCA_FORTRAN_ENABLED="1"

Python 2 and 3 bindings are available with OCCA. If you wish to setup the occa Python module, rather than using make, compile both libocca.so and the module with

python make.py

Examples

We have a few examples to show different features of OCCA. The addVectors example contains examples for each current supported language

• C++
• C
• Python
• Fortran
• Julia

Compile

To compile addVectors (Hello World! style example) in C++

cd examples/addVectors/cpp
make

Environment

Setup your LD_LIBRARY_PATH to point to libocca.so

export LD_LIBRARY_PATH+=':<occa>/lib'

where <occa> is the OCCA directory

Run

./main

Status

• Linux and OSX are fully supported

• Windows is partially supported

  • Code is up-to-date for windows
  • Missing compilation project/scripts
  • Visual Studio project is out of date

• OKL Status:

  • Supports most of C (send bugs =))
  • Preprocessor is missing variadic functions

• OFL Status:

  • Obsolete for now
  • Version 0.1 supports a subset of Fortran:
    • integer, real, character, logical, double precision
    • function, subroutine
    • DO, WHILE, IF, IF ELSE, ELSE

Useful environment variables:

Environment Variable	Description
OCCA_CACHE_DIR	Sets directory where kernels are cached (Default: ${HOME}/._occa
OCCA_INCLUDE_PATH	Adds directories to find headers
OCCA_LIBRARY_PATH	Adds directories to find libraries
OCCA_CXX	C++ compiler used for libocca.so and run-time compilation
OCCA_CXXFLAGS	C++ compiler flags used for libocca.so and run-time compilation

OpenCL

Environment Variable	Description
OCCA_OPENCL_COMPILER_FLAGS	Adds additional OpenCL flags when compiling kernels

CUDA

Environment Variable	Description
OCCA_CUDA_COMPILER	Can be used to specify the CUDA compiler
OCCA_CUDA_COMPILER_FLAGS	Adds additional OpenCL flags when compiling kernels