feat: add batched real-FFT plans in float and double precision

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.5.0)
 if (NOT DEFINED GUI_BASE_DIR)
 	if (DEFINED ENV{GUI_BASE_DIR})
 		set(GUI_BASE_DIR $ENV{GUI_BASE_DIR})

DependencyTests/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.22)
 project(OpenEphysFFTWDependencySmokeTest LANGUAGES C)
 
 if(NOT DEFINED FFTW_ROOT)

README.md

@@ -4,6 +4,12 @@ This is a small library to wrap FFTW functionality useful for Open Ephys.
 
 It is currently used by the [Phase Calculator](https://github.com/tne-lab/phase-calculator) and Real-Time Coherence plugins (under development).
 
+`OpenEphysFFTWBatch.h` provides a lightweight, JUCE-independent batch API for
+aligned single- and double-precision real-to-complex and complex-to-real
+transforms. Batches are transform-major, with contiguous rows. Inverse
+transforms follow FFTW's convention and are not normalized. Create plans off
+real-time threads and reuse them.
+
 ## Dependency
 
 OpenEphysFFTW uses complete non-threaded, shared double- and single-precision
@@ -24,8 +30,8 @@ previously staged platform directory:
 cmake -S . -B Build -DFFTW_ROOT=/path/to/libs/linux
 ```
 
-Automatic staging requires CMake 3.24 or newer. Builds using `FFTW_ROOT` retain
-the project's CMake 3.15 minimum.
+Automatic staging requires CMake 3.19 or newer. Builds using `FFTW_ROOT` retain
+the project's existing CMake 3.5 minimum.
 
 The bundles intentionally omit the separate long-double, MPI, OpenMP, and
 threaded FFTW libraries. The `fftw3` and `fftw3f` libraries themselves are not

Source/OpenEphysFFTW.cpp

@@ -353,4 +353,4 @@ void FFTWTransformableArray::hilbert()
     fftReal();
     freqDomainHilbert();
     ifft();
-}
+}

Source/OpenEphysFFTW.h

@@ -32,6 +32,8 @@ transform library
 #include <CommonLibHeader.h>
 #include <complex>
 
+#include "OpenEphysFFTWBatch.h"
+
 // forward-declare:
 struct fftw_plan_s;
 
@@ -174,4 +176,4 @@ class FFTWTransformableArrayUsing : public FFTWTransformableArray
     {}
 };
 
-#endif // OEP_FFTW_H_INCLUDED
+#endif // OEP_FFTW_H_INCLUDED