TapTools kernel

The portable DSP library behind the TapTools Max package: header-only, plain C++20, no Max SDK, no min-api, no Jamoma. One self-contained header per object under include/taptools/, everything in the taptools namespace. The TapTools Max externals are thin Min shims over these kernels — the same split AmbiTap uses (AmbiTap = kernel library, AmbiTap-Max = wrappers).

This is a complete standalone CMake project. It lives in kernel/ of the TapTools monorepo and is designed to be lifted verbatim into its own repository (TapTools = kernel, TapTools-Max = wrappers); every path below is relative to this directory, so the layout and commands are the same either way.

What's here

Kernel	Max object	Contents
include/taptools/autowah.h	tap.autowah~	Snow White-style envelope filter (taptools::autowah)
include/taptools/ladder.h	tap.ladder~	ZDF Moog-style ladder (taptools::ladder)
include/taptools/svf.h	tap.svf~	Simper/Cytomic morphing SVF (taptools::svf)
include/taptools/vco.h	tap.vco~	Virtual-analog oscillator (taptools::vco)
include/taptools/grm_comb.h	tap.5comb~	GRM comb-bank recreation (taptools::fivecomb)
include/taptools/grm_pitchaccum.h	tap.pitchaccum~	GRM PitchAccum recreation (taptools::pitchaccum)
include/taptools/conv_engine.h	tap.convolve~	Partitioned (UPOLS) true-stereo convolution (taptools::conv_engine)

Plus, all Max-free:

• tests/ — Catch2 unit tests for the kernels (fetched via FetchContent; run with ctest). Wrapper-level tests (attributes, Min plumbing) stay with the externals on the min-api harness in the Max package.
• tools/render/ — offline WAV renderers (ladder_render, vco_render, grm_comb_render, grm_pitchaccum_render, autowah_render) for listening checks outside Max.
• tools/capi/ — a small C ABI (taptools_capi) over the kernels for non-C++ consumers: conv_engine, svf, ladder, vco, and autowah.
• notebooks/ — Jupyter verification notebooks driving the actual shipping DSP through the C ABI via ctypes (taptools_py.py): convolution_reverb.ipynb, svf.ipynb, ladder.ipynb, vco.ipynb, and autowah_validation.ipynb (the hardware-calibration harness for the Snow White model — its last section ingests reamped recordings of the real pedal).
• bench/ — CPU benchmarks and the per-machine regression ratchet (see bench/README.md).
• book/ — Tools on Tap, the mdBook field guide (the AmbiTap/SampleRateTap/MuTap book pattern): one chapter per object family, every claim measured by the notebooks/tests. Built and published to Pages by .github/workflows/docs.yml. Ten user-facing chapters across four parts — sources (vco), filters (svf, ladder, autowah), strings/rooms/spirals (convolve, 5comb, pitchaccum), the spectral set (vocoder, nr, spectra) — plus Part V, "The machine, file by file": one deep-dive appendix per kernel header (SampleRateTap-style) deriving the math, reviewing the code, and recording why each algorithm is built the way it is.

Build & test

From this directory (as its own repo, or -S kernel from the monorepo root):

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
ctest --test-dir build --output-on-failure

CMake exports the header-only target TapTools::taptools; TAPTOOLS_BUILD_{TESTS,TOOLS,BENCH} and TAPTOOLS_INSTALL default to on only when the kernel is the top-level project. Installing provides a find_package(TapToolsKernel) config package.

How the Max package consumes it

The Max package's CMakeLists.txt points its externals at ${TAPTOOLS_KERNEL_DIR}/include (TAPTOOLS_KERNEL_DIR defaults to the in-tree kernel/; override it with -DTAPTOOLS_KERNEL_DIR=/path/to/kernel to build against an external checkout). Once this kernel is its own repository, the Max package pins it as a git submodule and points TAPTOOLS_KERNEL_DIR there, per the AmbiTap-Max pattern.

Rules

• Kernels depend on the C++ standard library only. Anything Max-specific belongs in the wrapper.
• Headers are C++20. The consuming Max wrapper .cpps and their min-api unit tests compile at C++20 as well, so C++20 features are fair game.
• Sharing code between kernels is allowed here (that's much of the point — e.g. the radix-2 FFT duplicated between conv_engine.h and tap.nr~ should consolidate here); the Max-side "each object is self-contained" rule applies to the wrapper package, not to the kernel.
• Provenance and algorithm notes live in each header's top comment. The Max package's REVIVAL.md is the roadmap, including which objects' DSP is still inline Max-side and next to extract.