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goattrackerplugin

Plays GoatTracker v2 native song files (.sng) — the C64 SID tracker by Lasse Öörni (Cadaver). GoatTracker's own playback core is vendored and driven directly, with no SDL / BME / editor layer:

  • gplay.c / gplay.h — the GoatTracker v2 sequencer (playroutine), verbatim, patched only to include gt2_engine.h instead of the heavy goattrk2.h.
  • gsid.cpp / gsid.h — GoatTracker's reSID interface (sid_init, sid_fillbuffer), trimmed to plain reSID only (the reSID-fp path removed).
  • resid/ — Dag Lem's reSID 6581/8580 emulator, vendored verbatim (minus version.cpp, which only exposes the autoconf VERSION string).
  • gt2_load.c — the loader. GoatTracker's loadsong is vendored verbatim (as loadsong_impl), adapted only by swapping its editor-model calls (clearsong → a local clear_arrays, songchange and the table-view resets dropped) so it needs none of the editor modules. It handles every song version — GTS! (v1), GTS2 (3-table) and GTS3/GTS4/GTS5 — including the intricate v1 wave/pulse/filter/arpeggio conversion and the version-gated pulse-speed (<v2.4) and legato/nohr (<v2.5) fixups. This file also owns the song arrays, the player-config globals (fixed at GoatTracker's PAL / 6581 / 1× defaults), makespeedtable (from gtable.c) and no-op stubs for the BME timing / SDL flush hooks.
  • gt2_engine.h — lightweight umbrella header exposing exactly what the sequencer needs.

Format dispatch

.sng is heavily overloaded, so the format is claimed by content magic only (GTS!/GTS2/GTS3/GTS4/GTS5). UADE (tried first for .sng) declines non-Richard-Joseph .sng, and SCC-Musixx rejects GTS, so the three coexist.

Playback / end detection

reSID renders mono; the plugin drives playroutine() once per 50 Hz PAL frame, fans the output out to interleaved stereo, and detects end-of-song when every channel's order-list position has wrapped once (one full pass), on an explicit stopsong, or at a 600 s cap.

Symbols

GoatTracker and reSID export many generic un-prefixed globals (pattern, instr, sid, sidreg, sound_flush, …) that collide with other vendored plugins, so the library is compiled with hidden visibility and partial-linked (ld -r) to localize everything except musix::GoatTrackerPlugin / goattrackerplugin_register — the same approach as mikmodplugin.

Credits / license

  • GoatTracker © Lasse Öörni (Cadaver) — GNU GPL v2.
  • reSID © 2004 Dag Lem <resid@nimrod.no> — GNU GPL v2.

Both components are GPL v2; this plugin is therefore GPL v2. See LICENSE.