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- For whatever reasons, v2019.1 can C-Simulate CCordicAbs, but cannot C-Synthetize it. So the process member function have been mirrored to a static process function in the top level, called directly. It just works. - The TCL script have been amended to support both Vivado_HLS 2019.1 and Vitis_HLS 2020.2 (maybe .1 also, but hasn't been tested). - The CMake project works and is validated for G++ > 6.2, so can't be used with vivado less than 2020.1 (which use 4.6.3). This vivado version must be used with the TCL script directly. - A custom target `run_hls` has been created to call vitis_hls 2020.2 if ENABLE_XILINX and ENABLE_TESTING have been specified. It is called by ctest by default. It can produce an IP (option IP_XILINX) and run Vivado implementation design flow (option IMPL_XILINX).
2.7 KiB
CORDIC Abs APFX
A free way to implement a CORDIC-based Complex Absolute Value using HLS, with bit-accurate precision.
Goal
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 also can be used to approximate the module of a complex. It is also useful for microcontrollers or microprocessors lacking floating-point units, as such multiplications can consume a noticeable amount of CPU cycles.
Indeed, |z| = sqrt(x² + y²) = |exp(-j*angle(z)) * z|, thus the module of z is the absolute value of the real part of its rotated version. So, ... CORDIC!
This implementation in C++14 (-std=c++14) is suitable for hardware simulation and (with the right headers and maybe a few tweaks) for synthesis.
This repository defines one working CORDIC-based Absolute Value units class, CCordicAbs.
Test suite and dependencies
The Catch2 test framework has been used in conjunction with CTest to provides unit tests.
- Has been tested successfully compiled with:
- GNU GCC 6.2 (Xilinx bundled version), 6.5, 9.4, 10.1, 10.2 and 11.2,
- LLVM Clang 12.0 and 13.0,
- Uses Catch v2.13.7,
- Depends on Xilinx HLS arbitrary precision types, available as FOSS here provided by Xilinx or here patched by myself. Note: Xilinx also provides proprietary versions of those headers, suitable for synthesis and implementation, bundled with their products.
A Xilinx C++ HLS testbench is also available, as well as a TCL script to run simulation, synthesis, co-simulation and IP export and implementation if wanted. Xilinx HLS v2020.2 can be directly called from CMake by the target run_hls if the options ENABLE_TESTING, ENABLE_XILINX and COSIM_XILINX are enabled. If CMake feels like black magic, It is advice to use tools like ccmake (NCurses terminal interface to cmake) or cmake-gui.
License and copyright
Copyright 2022 Camille "DrasLorus" Monière.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
A copy of the license is available here in Markdown or here in plain text.