# occa
**Repository Path**: mirrors_GerHobbelt/occa
## Basic Information
- **Project Name**: occa
- **Description**: Portable and vendor neutral framework for parallel programming on heterogeneous platforms.
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No
## Statistics
- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-11-08
- **Last Updated**: 2026-03-21
## Categories & Tags
**Categories**: Uncategorized
**Tags**: None
## README
[](LICENSE)
[][OCCA_SLACK]
[](https://twitter.com/libocca)
## Performance, Portability, Transparency
OCCA is an open source, portable, and vendor neutral framework for parallel programming on heterogeneous platforms. The OCCA API provides unified models for heterogeneous programming concepts—such as a device, memory, or kernel—while the OCCA Kernel Language (OKL) enables the creation of portable device kernels using a directive-based extension to the C-language.
Mission critical computational science and engineering applications from the public and private sectors rely on OCCA. Notable users include the U.S. Department of Energy and Shell.
**Key Features**
- **Multiple backends**—including CUDA, HIP, Data Parallel C++, OpenCL, OpenMP (CPU), and Metal
- **JIT compilation** and caching of kernels
- C, C++, and ***Fortran*** language support
- **Interoperability** with backend API and kernels
- **Transparency**—easy to understand how your code is mapped to each platform
## Requirements
### Minimum
- [CMake] v3.21 or newer
- C++17 compiler
- C11 compiler
### Optional
- Fortan 90 compiler
- CUDA 9 or later
- HIP 4.2 or later
- SYCL 2020 or later
- OpenCL 2.0 or later
- OpenMP 4.0 or later
## Build, Test, Install
OCCA uses the [CMake] build system. Checkout the [installation guide](INSTALL.md) for a comprehensive overview of all build settings and instructions for building on [Windows](INSTALL.md#windows) or [Mac OS](INSTALL.md#mac-os).
### Linux
For convenience, the shell script `configure-cmake.sh` has been provided to drive the CMake build. Compilers, flags, and other build parameters can be adjusted there. By default, this script uses `./build` and `./install` for the build and install directories.
The following demonstrates a typical sequence of shell commands to build, test, and install occa:
```shell
$ ./configure-cmake.sh
$ cmake --build build --parallel
$ ctest --test-dir build --output-on-failure
$ cmake --install build --prefix install
```
If dependencies are installed in a non-standard location, set the corresponding [environment variable](INSTALL.md#dependency-paths) to this path.
## Use
### Environment
During installation, the [Env Modules](Env_Modules) file `/modulefiles/occa` is generated. When this module is loaded, paths to the installed `bin`, `lib`, and `include` directories are appended to environment variables such as `PATH` and `LD_LIBRARY_PATH`.
### Building an OCCA application
For convenience, OCCA provides CMake package files which are configured during installation. These package files define an imported target, `OCCA::libocca`, and look for all required dependencies.
For example, the CMakeLists.txt of downstream projects using OCCA would include
```cmake
find_package(OCCA REQUIRED)
add_executable(downstream-app ...)
target_link_libraries(downstream-app PRIVATE OCCA::libocca)
add_library(downstream-lib ...)
target_link_libraries(downstream-lib PUBLIC OCCA::libocca)
```
### Command-line Interface
The OCCA command-line interface can be found in `/bin/occa`. This tool can be used to query information about hardware and the configuration of OCCA on a given platform.
For example, calling `occa info` will available OCCA backends and related hardware specs, while `occa env` display the values of OCCA related environment variables. To see the list of all available options, call `occa --help`.
```shell
$ occa info
========+======================+=================================
CPU(s) | Processor Name | AMD EPYC 7532 32-Core Processor
| Memory | 251.6 GB
| Clock Frequency | 2.4 MHz
| SIMD Instruction Set | SSE2
| SIMD Width | 128 bits
| L1d Cache Size | 1 MB
| L1i Cache Size | 1 MB
| L2 Cache Size | 16 MB
| L3 Cache Size | 256 MB
========+======================+=================================
OpenCL | Platform 0 | NVIDIA CUDA
|----------------------+---------------------------------
| Device 0 | NVIDIA A100-PCIE-40GB
| Device Type | gpu
| Compute Cores | 108
| Global Memory | 39.40 GB
========+======================+=================================
CUDA | Device Name | NVIDIA A100-PCIE-40GB
| Device ID | 0
| Memory | 39.40 GB
========+======================+=================================
```
## Community
### Support
Need help? Checkout the [repository wiki](https://github.com/libocca/occa/wiki) or ask a question in the [Q&A discussions category](https://github.com/libocca/occa/discussions/categories/q-a).
### Feedback
To provide feedback, start a conversation in the [general](https://github.com/libocca/occa/discussions/categories/general) or [ideas](https://github.com/libocca/occa/discussions/categories/ideas) discussion categories.
## Acknowledgements
This work was supported in part by
- Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357
- The Exascale Computing Project (17-SC-20-SC), a joint project of the U.S. Department of Energy’s Office of Science and National Nuclear Security Administration, responsible for delivering a capable exascale ecosystem, including software, applications, and hardware technology, to support the nation’s exascale computing imperative
- The Center for Efficient Exascale Discretizations (CEED), a co-design center within the U.S. Department of Energy Exascale Computing Project.
- Intel
- AMD
- Shell
## License
OCCA is available under a [MIT license](LICENSE.MD)
[OCCA_WEBSITE]: https://libocca.org
[OCCA_SLACK]: https://join.slack.com/t/libocca/shared_invite/zt-4jcnu451-qPpPWUzhm7YQKY_HMhIsIw
[CMake]: https://cmake.org/
[Env_Modules]: https://modules.readthedocs.io/en/latest/index.html