WDF Compiler

WDF Compiler is a code generation system for developing circuit simulations using Wave Digital Filters (WDFs).

Usage

WDF Compiler is intended to be used as follows:

1. Write your circuit description
2. Use wdf_compiler to generate your circuit simulation code
3. Compile the generated code into your own executable

Circuit Description

wdf_compiler uses its own circuit description language. To write a circuit description, you can declare each WDF element in your circuit, followed by that element's "children". For example, here is a circuit description for a simple RC lowpass filter:

circuit:
IVs(Vin);
    Series(S1);
        R(R1, 1k);
        C(C1, 1u);

inputs:
Vin

outputs:
V:C1

For more examples of the circuit description language, see the tests/ directory.

Compilation Stage

Let's say that you've written your circuit description in a file called my_circuit.wdf. Simulation code can be generated for the circuit using the command:

wdf_compiler my_circuit.wdf my_circuit.h

By default, wdf_compiler will generate C++ code, using float as the base data type. wdf_compiler also supports generating code in C, JAI, and Rust:

wdf_compiler -lang jai my_circuit.wdf my_circuit.jai

wdf_compiler also supports generating code using arbitrary data types:

wdf_compiler -dtype double my_circuit.wdf my_circuit.h

Run wdf_compiler -help to see additional options.

Development

Building

To build the wdf_compiler for yourself, you must have the JAI compiler installed. wdf_compiler is currently built with JAI beta version 0.2.023, but most recent versions should work.

To build the compiler, run:

jai compiler/wdf_compiler.jai

Tests

To run the wdf_compiler tests, run:

./tests/test_runner.sh

Performance Benchmarks

To run the wdf_compiler performance benchmarks, run:

./tests/test_runner.sh clang bench

Performance Measurements

The following tables show the output of the performance benchmarks for wdf_compiler version 1.1.0. Along with wdf_compiler, the benchmarks compare these other WDF libraries: chowdsp_wdf, wdmodels, and RT-WDF.

CPU: Apple M1

Circuit	Framework	ns/sample	instructions/sample	cycles/sample	instructions/cycle
RC Lowpass	RT-WDF	22.54	251.02	72.07	3.48
RC Lowpass	wdmodels	6.02	17.01	19.04	0.89
RC Lowpass	chowdsp_wdf	6.97	18.01	22.09	0.82
RC Lowpass	wdf_compiler	1.37	12.00	4.42	2.71
Pre-Amp EQ	RT-WDF	107.66	1007.10	346.18	2.91
Pre-Amp EQ	wdmodels	22.91	83.02	73.30	1.13
Pre-Amp EQ	chowdsp_wdf	20.71	56.01	66.33	0.84
Pre-Amp EQ	wdf_compiler	18.42	66.02	59.18	1.12
Diode Clipper	wdmodels	116.52	566.93	374.53	1.51
Diode Clipper	chowdsp_wdf	41.05	102.04	131.78	0.77
Diode Clipper	wdf_compiler	35.08	76.02	112.79	0.67
Baxandall EQ	RT-WDF	183.01	2028.18	588.16	3.45
Baxandall EQ	wdmodels	18.54	163.02	59.23	2.75
Baxandall EQ	chowdsp_wdf	20.52	156.01	65.55	2.38
Baxandall EQ	wdf_compiler	11.35	55.01	36.56	1.50

CPU: AMD Ryzen Zen 4

Circuit	Framework	ns/sample	instructions/sample	cycles/sample	instructions/cycle
RC Lowpass	RT-WDF	20.31	268.06	99.85	2.68
RC Lowpass	wdmodels	2.98	14.51	15.03	0.97
RC Lowpass	chowdsp_wdf	6.44	38.02	31.73	1.20
RC Lowpass	wdf_compiler	1.21	9.51	6.06	1.57
Pre-Amp EQ	RT-WDF	99.98	1132.51	505.42	2.24
Pre-Amp EQ	wdmodels	15.92	128.05	80.29	1.59
Pre-Amp EQ	chowdsp_wdf	18.96	136.05	95.77	1.42
Pre-Amp EQ	wdf_compiler	12.77	83.03	63.35	1.31
Diode Clipper	wdmodels	90.17	354.14	389.10	0.91
Diode Clipper	chowdsp_wdf	28.31	126.24	141.86	0.89
Diode Clipper	wdf_compiler	22.84	96.07	113.12	0.85
Baxandall EQ	RT-WDF	160.94	2406.47	805.60	2.99
Baxandall EQ	wdmodels	14.66	261.04	72.95	3.58
Baxandall EQ	chowdsp_wdf	22.17	199.19	112.25	1.77
Baxandall EQ	wdf_compiler	8.58	95.02	43.62	2.18

In The Wild

wdf_compiler has been successfully used for several prototype and professional projects, including:

• wdf_compiler_plugin: An audio plugin for prototyping WDF circuit models, with hot reloading.
• Tekno: A drum machine plugin containing several WDF circuit models. wdf_compiler was able to improve the performance of these circuit models by 20-50%.

License

WDF Compiler is open-source software published under the MIT.