Skip Elegy of Emptiness playback after it's been played once

Makes Stone Tower a bit less tedious, considering Link needs to play
it 10+ times to climb the tower and complete the dungeon normally.

The song playback is entirely skipped after the song has been
played once during the current play session.

Fixes #12

source/CMakeLists.txt

@@ -29,6 +29,7 @@ add_executable(newcode
   game/static_context.cpp
   game/static_context.h
   game/sound.cpp
+  rst/fixes/ocarina.cpp
   rst/fixes/time.cpp
   rst/fixes.cpp
   rst/fixes.h

source/common/utils.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <algorithm>
 #include <cstring>
 #include <tuple>
 #include <type_traits>
@@ -54,4 +55,14 @@ void Write(T* ptr, size_t offset, const ValueType& value) {
   std::memcpy(reinterpret_cast<u8*>(ptr) + offset, &value, sizeof(value));
 }
 
+template <class InputIt, class T>
+bool Contains(InputIt first, InputIt last, const T& value) {
+  return std::find(first, last, value) != last;
+}
+
+template <class C, class T>
+bool Contains(const C& c, const T& value) {
+  return Contains(std::begin(c), std::end(c), value);
+}
+
 }  // namespace rst::util

source/game/context.cpp

@@ -28,6 +28,10 @@ act::Actor* GlobalContext::SpawnActor(act::Actor* actor, act::Id id, u16 rx, u16
   return spawn_actor_wrapper(&actors, actor, this, id, rx, ry, rz, param, pos_x, pos_y, pos_z);
 }
 
+void GlobalContext::ShowMessage(u16 msgid, int unknown) {
+  rst::util::GetPointer<void(GlobalContext*, int msgid, int)>(0x21BAFC)(this, msgid, unknown);
+}
+
 namespace {
 
 class Screen;

source/game/context.h

@@ -123,6 +123,8 @@ struct GlobalContext {
   act::Actor* SpawnActor(act::Actor* actor, act::Id id, u16 rx, u16 ry, u16 rz, u16 param,
                          float pos_x, float pos_y, float pos_z);
 
+  void ShowMessage(u16 msgid, int unknown = 0);
+
   int field_0;
   u8 gap_4[36];
   pad::State pad_state;

source/rst/fixes/ocarina.cpp

@@ -0,0 +1,67 @@
+#include "common/context.h"
+#include "common/debug.h"
+#include "common/types.h"
+#include "game/context.h"
+#include "game/sound.h"
+
+namespace game::ui {
+class MessageWindow;
+};
+
+namespace rst {
+
+static void EndOcarinaSession(game::ui::MessageWindow* window) {
+  const auto set_ocarina_fadeout = util::GetPointer<void(int zero, int duration)>(0x4FE0BC);
+  set_ocarina_fadeout(0, 30);
+
+  const auto set_ocarina_mode =
+      util::GetPointer<void(game::ui::MessageWindow*, int mode)>(0x1D1A18);
+  set_ocarina_mode(window, 1);
+
+  auto* gctx = GetContext().gctx;
+  // Disable BGM fadeout
+  util::Write(gctx, 0x8422, 1);
+  gctx->ocarina_state = game::OcarinaState::StoppedPlaying;
+}
+
+static bool IsElegyOfEmptinessAllowed() {
+  constexpr u16 allowed_maps[] = {0x58, 0x59, 0x53, 0x1D, 0x56, 0x13, 0x16, 0x18, 0x60, 0x4B, 0x51};
+  return util::Contains(allowed_maps, GetContext().gctx->map_maybe);
+}
+
+// Returns true to make the caller return, false to continue.
+bool HandleOcarinaSong(game::ui::MessageWindow* self, game::OcarinaSong song) {
+  if (song == game::OcarinaSong::ElegyOfEmptiness) {
+    static bool s_played_once = false;
+    util::Print("%s: played the Elegy of Emptiness (once=%u)", __func__, s_played_once);
+    if (!s_played_once) {
+      s_played_once = true;
+      return false;
+    }
+
+    EndOcarinaSession(self);
+
+    auto* gctx = GetContext().gctx;
+    if (IsElegyOfEmptinessAllowed()) {
+      game::sound::PlayEffect(0x1000773);
+      gctx->ocarina_song = game::OcarinaSong::ElegyOfEmptiness;
+      gctx->ocarina_state = game::OcarinaState::PlayingAndReplayDone;
+    } else {
+      gctx->ShowMessage(0x1B95, 0);  // "Your notes echoed far..."
+      gctx->ocarina_state = game::OcarinaState::StoppedPlaying;
+      util::GetPointer<void(int)>(0x1D8C5C)(0);
+    }
+
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace rst
+
+extern "C" {
+RST_HOOK bool rst_HandleOcarinaSong(game::ui::MessageWindow* self, game::OcarinaSong song) {
+  return rst::HandleOcarinaSong(self, song);
+}
+}

source/rst/trampolines.s

@@ -50,3 +50,22 @@ TRAMPOLINE_DECLARE rst_ui_items_GetItemAssignIndex
   mov r3, r0
   vpop {d0-d15}
   pop {r0-r2, r4-r12, pc}
+
+TRAMPOLINE_DECLARE rst_HandleOcarinaSong
+  push {lr}
+
+  push {r0-r12}
+  vpush {d0-d15}
+  mov r1, r0 // song
+  mov r0, r4 // MessageWindow* this
+  bl rst_HandleOcarinaSong
+  cmp r0, #0
+  vpop {d0-d15}
+  pop {r0-r12}
+
+  // jump out of this trampoline and MessageWindow code directly
+  addne sp, sp, #0x70
+  popne {r4-r11, pc}
+
+  cmp r0, #0x16 // original instruction
+  pop {pc}

v100/hooks.hks

@@ -207,3 +207,9 @@ ui_items_fast_assign_item:
   link: true
   func: rst_trampoline_rst_ui_items_GetItemAssignIndex
   addr: 0x5C161C
+
+messagewindow_handle_ocarina_song_hook:
+  type: branch
+  link: true
+  func: rst_trampoline_rst_HandleOcarinaSong
+  addr: 0x604D8C