libcRSID

This is a single-header adaptation of the library version of cRSID for embedding in game engines or other applications. Changes have been made for easier compilation in C/C++ environments and with varying compilers (tested with MSVC, GCC, and Clang across different operating systems). SDL and filesystem references have been removed; the library is intended to receive an in-memory SID track and produce samples on demand.

Compilation

Define CRSID_IMPLEMENTATION before including libcRSID.h in one source file within your project. It can then be included anywhere else that it needs to be referenced.

To compile a test program, please use the CMakeLists file in the example directory. It will build a small program that displays a window and replays an embedded SID file, or if passed a filepath as the first parameter will attempt to play it.

• The test program uses the Sokol libraries which are zlib-licensed and is based on the mod player example from sokol-samples, which is MIT licensed. Neither of these licenses affect libcRSID when compiled on its own.

Usage

• Initialize a cRSID_C64instance pointer with the cRSID_init function, passing the desired frequency/sampling rate as a parameter and a boolean to enable/disable the higher-quality wave generators (at the expense of increased overhead).
• Initialize a cRSID_SIDheader pointer with the cRSID_processSIDbuffer function, passing the previously created cRSID_C64instance as well as a pointer to a memory buffer containing the SID track and its length as parameters.
  • NOTE: The cRSID_SIDheader will use the same pointer as the memory buffer you passed to it here. It is NOT safe to free this buffer until you are completely done with the track!
• Alternatively, initialize a cRSID_SIDheader pointer with the cRSID_processSIDfile function, passing the previously created cRSID_C64instance as well as a file path to a valid SID file.
  • If a track is loaded with this method, it will create an internal buffer that, unlike with cRSID_processSIDbuffer, will be freed when cRSID_reset is called.
• Prepare the SID track for playback with the cRSID_initSIDtune function, passing the cRSID_C64instance, cRSID_SIDheader, and the number of the subtune to play (or 0 if not applicable). This will not generate any audio yet.
• In an appropriate place in your program, call the cRSID_generateSound function, passing the cRSID_C64instance, a pointer to an initialized buffer to store the generated samples and its length as parameters. Generated samples will be in the form of pairs of signed 16-bit integers.
  • Alternatively, cRSID_generateFloat can be used to produce floating point output.
• When finished, hard-reset the SID with the cRSID_reset function, passing the cRSID_C64instance as a parameter. Do NOT try to free the memory represented by the cRSID_C64instance pointer after this; rather set it to NULL as with the way cRSID works under the hood this will remove a global cRSID_C64instance that the library relies on. Next, set the cRSID_SIDheader pointer to NULL and then free the memory represented by the original pointer used to instantiate it (if not planning to reuse it).