mirror of
https://github.com/DrasLorus/CORDIC_Rotate_APFX.git
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46 lines
2.8 KiB
Markdown
46 lines
2.8 KiB
Markdown
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# CORDIC Rotate APFX
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A free way to implement a CORDIC-based rotation using HLS, with bit-accurate precision.
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## Goal
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[CORDIC](https://en.wikipedia.org/wiki/CORDIC) (COordinate Rotation DIgital Computer) is an efficient way to implement hardware complex rotations (e.g. `z * exp(jw)`, with `z = x + jy` a complex and `w` a real angle). It is also useful for microcontrollers or microprocessors lacking floating-point units, as such multiplications can consume a noticeable amount of CPU cycles.
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This implementation in C++14 (`-std=c++14`) is suitable for hardware simulation and (with the right lib's and a few tweaks) for synthesis.
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This repository mainly hosts `CCordicRotateHalfPiRom`, CORDIC-based rotation units which rely on a ROM.
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Currently, It ranges from 2 to 7 stages, and the word length is a template.
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It depends on ROM generators, each one producing a ROM table which contains control signals for each CORDIC stage, depending on the input angle. There are generators:
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- A true `constexpr` one, that is entirely processed by the compiler.
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- A Monte-Carlo one, that is evaluated at runtime and can be used to produced ROM-headers, suitable for Autoconf/CMake header generations.
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Only rotations of pi and pi/2 are currently supported, but support for any pi/2^k can be easily added.
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`CCordicRotate` is an unfinished template that would implement a *smart* CORDIC, which can work without a ROM.
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## Test suite and dependencies
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The [Catch2](https://github.com/catchorg/Catch) test framework has been used in conjunction with CTest to provides unit tests.
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The [GitHub mirror of the repository](https://github.com/DrasLorus/CORDIC_Rotate_APFX) also make use of GitHub Actions and Docker as a CI/CD solution.
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- Has been tested successfully compiled with:
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- GNU GCC 9.4, 10.1, 10.2 and 11.2,
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- LLVM Clang 12.0 and 13.0,
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- Uses Catch v2.13.7,
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- Depends on Xilinx HLS arbitrary precision types, available as FOSS [here provided by Xilinx](https://github.com/Xilinx/HLS_arbitrary_Precision_Types) or [here patched by myself](https://github.com/DrasLorus/HLS_arbitrary_Precision_Types). Note: Xilinx also provides proprietary versions of those headers, suitable for synthesis and implementation, bundled with their products.
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## License and copyright
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Copyright 2022 Camille "DrasLorus" Monière.
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This program is free software: you can redistribute it and/or modify it under the terms of the GNU
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Lesser General Public License as published by the Free Software Foundation, either version 3 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
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even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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A copy of the license is available [here in Markdown](lgpl-3.0.md) or [here in plain text](LICENSE).
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