Interface: Pure Data

The Arrp compiler can generate C++ code for a Pure Data external object using the option --interface puredata.

CMake helps automate the process of generating this C++ code and further compiling it into a dynamic library.

Example

This example demonstrates how to create a Pure Data external object from simple Arrp code that outputs a sine wave at 440 Hz.

Prerequisites:

CMake (Ubuntu, Mac OS)
Pure Data development headers (come with Pure Data) (Ubuntu, Mac OS)
Portable Coroutine Library (Ubuntu, Mac OS - Homebrew)

Code

Place the following files into the same directory:

osc.arrp
CMakeLists.txt

osc.arrp:

input samplerate : int;
input freq : [~]real64;
output y : [~]real64;

y = osc(freq, 0.0);

osc(freq, init_ph) =
  sin(ph * 2 * pi) where
    ph = phase(freq, init_ph);

phase(freq, init) = p where
{
    p[0] = init;
    p[n] = wrap(p[n-1] + freq[n-1] / samplerate);
};

wrap(x) = x - floor(x);

pi = atan(1) * 4;

CMakeLists.txt:

cmake_minimum_required(VERSION 3.0)

project(arrp-osc)

# Uncomment and adjust the following line
# to specify non-standard location of the Arrp compiler
# set(CMAKE_PREFIX_PATH "path where Arrp is installed")

find_package(Arrp REQUIRED)

arrp_to_pd(arrp_osc osc.arrp)

Procedure (Linux, Mac OS)

In the directory containing the above files, use the following commands to generate a Pure Data library named arrp_osc~.pd_linux on Linux or arrp_osc~.pd_darwin on Mac OS:
```
 mkdir build
 cd build
 cmake -D CMAKE_BUILD_TYPE=Release ..
 make arrp_osc
```
Note: If you want machine code that's easier to debug, replace the cmake command with:
```
 cmake -D CMAKE_BUILD_TYPE=Debug ..
```
Copy the generated library into your Pure Data external location.
In Pure Data, you can now create an object arrp_osc~. The object has 1 signal outlet producing a sine wave, and 1 signal inlet controlling the sine wave frequency.