Stream music instead of loading it all at once

RAM usage (my beefy desktop):

* Town: 176 MiB -> 121 MiB
* Cathedral: 191 MiB -> 138 MiB

Performance: 1170 FPS -> 1150 FPS

CMakeLists.txt

@@ -289,6 +289,7 @@ set(devilutionx_SRCS
   SourceX/thread.cpp
   SourceX/sound.cpp
   SourceX/soundsample.cpp
+  SourceX/storm_sdl_rw.cpp
   SourceX/storm/storm.cpp
   SourceX/storm/storm_net.cpp
   SourceX/dvlnet/abstract_net.cpp

SourceS/miniwin/misc.h

@@ -62,6 +62,7 @@ bool PostMessage(UINT Msg, WPARAM wParam, LPARAM lParam);
 // MSCVRT emulation
 //
 
+#define DVL_FILE_BEGIN 0
 #define DVL_FILE_CURRENT 1
 #define DVL_FILE_END 2
 

SourceX/sound.cpp

@@ -6,6 +6,7 @@
 #include "all.h"
 #include "../3rdParty/Storm/Source/storm.h"
 #include "stubs.h"
+#include "storm_sdl_rw.h"
 #include <SDL.h>
 #include <SDL_mixer.h>
 
@@ -15,9 +16,11 @@ BOOLEAN gbSndInited;
 /** Specifies whether background music is enabled. */
 HANDLE sghMusic;
 
+namespace {
+
 Mix_Music *music;
-SDL_RWops *musicRw;
-char *musicBuffer;
+
+} // namespace
 
 /* data */
 
@@ -157,12 +160,10 @@ void music_stop()
 {
 	if (sghMusic) {
 		Mix_HaltMusic();
-		SFileCloseFile(sghMusic);
-		sghMusic = NULL;
 		Mix_FreeMusic(music);
 		music = NULL;
-		musicRw = NULL;
-		mem_free_dbg(musicBuffer);
+		SFileCloseFile(sghMusic);
+		sghMusic = NULL;
 		sgnMusicTrack = NUM_MUSIC;
 	}
 }
@@ -183,17 +184,25 @@ void music_start(int nTrack)
 		if (!success) {
 			sghMusic = NULL;
 		} else {
-			int bytestoread = SFileGetFileSize(sghMusic, 0);
-			musicBuffer = (char *)DiabloAllocPtr(bytestoread);
-			SFileReadFile(sghMusic, musicBuffer, bytestoread, NULL, 0);
-
-			musicRw = SDL_RWFromConstMem(musicBuffer, bytestoread);
-			if (musicRw == NULL) {
-				ErrSdl();
+			music = Mix_LoadMUSType_RW(SFileRw_FromStormHandle(sghMusic), MUS_NONE, /*freesrc=*/1);
+			if (music == NULL) {
+				SDL_Log("Mix_LoadMUSType_RW: %s", Mix_GetError());
+				SFileCloseFile(sghMusic);
+				sghMusic = NULL;
+				sgnMusicTrack = NUM_MUSIC;
+				return;
 			}
-			music = Mix_LoadMUSType_RW(musicRw, MUS_NONE, 1);
+
 			Mix_VolumeMusic(MIX_MAX_VOLUME - MIX_MAX_VOLUME * sgOptions.Audio.nMusicVolume / VOLUME_MIN);
-			Mix_PlayMusic(music, -1);
+			if (Mix_PlayMusic(music, -1) < 0) {
+				SDL_Log("Mix_PlayMusic: %s", Mix_GetError());
+				Mix_FreeMusic(music);
+				SFileCloseFile(sghMusic);
+				sghMusic = NULL;
+				music = NULL;
+				sgnMusicTrack = NUM_MUSIC;
+				return;
+			}
 
 			sgnMusicTrack = nTrack;
 		}

SourceX/storm_sdl_rw.cpp

@@ -0,0 +1,88 @@
+#include "storm_sdl_rw.h"
+
+#include "all.h"
+#include "../3rdParty/Storm/Source/storm.h"
+#include "../Source/engine.h"
+
+namespace dvl {
+
+static HANDLE SFileRw_GetHandle(struct SDL_RWops *context)
+{
+	return (HANDLE)context->hidden.unknown.data1;
+}
+
+static void SFileRw_SetHandle(struct SDL_RWops *context, HANDLE handle)
+{
+	context->hidden.unknown.data1 = handle;
+}
+
+#ifndef USE_SDL1
+static Sint64 SFileRw_size(struct SDL_RWops *context)
+{
+	DWORD result;
+	if (!SFileGetFileSize(SFileRw_GetHandle(context), &result))
+		return -1;
+	return result;
+}
+#endif
+
+#ifndef USE_SDL1
+static Sint64 SFileRw_seek(struct SDL_RWops *context, Sint64 offset, int whence)
+#else
+static int SFileRw_seek(struct SDL_RWops *context, int offset, int whence)
+#endif
+{
+	DWORD swhence;
+	switch (whence) {
+	case RW_SEEK_SET:
+		swhence = DVL_FILE_BEGIN;
+		break;
+	case RW_SEEK_CUR:
+		swhence = DVL_FILE_CURRENT;
+		break;
+	case RW_SEEK_END:
+		swhence = DVL_FILE_END;
+		break;
+	default:
+		return -1;
+	}
+	return SFileSetFilePointer(SFileRw_GetHandle(context), offset, NULL, swhence);
+}
+
+#ifndef USE_SDL1
+static size_t SFileRw_read(struct SDL_RWops *context, void *ptr, size_t size, size_t maxnum)
+#else
+static int SFileRw_read(struct SDL_RWops *context, void *ptr, int size, int maxnum)
+#endif
+{
+	DWORD num_read = 0;
+	SFileReadFile(SFileRw_GetHandle(context), ptr, maxnum * size, &num_read, NULL);
+	return num_read;
+}
+
+static int SFileRw_close(struct SDL_RWops *context)
+{
+	mem_free_dbg(context);
+	return 0;
+}
+
+SDL_RWops *SFileRw_FromStormHandle(HANDLE handle)
+{
+	SDL_RWops *result = (SDL_RWops *)DiabloAllocPtr(sizeof(SDL_RWops));
+
+#ifndef USE_SDL1
+	result->size = &SFileRw_size;
+	result->type = SDL_RWOPS_UNKNOWN;
+#else
+	result->type = 0;
+#endif
+
+	result->seek = &SFileRw_seek;
+	result->read = &SFileRw_read;
+	result->write = NULL;
+	result->close = &SFileRw_close;
+	SFileRw_SetHandle(result, handle);
+	return result;
+}
+
+} // namespace dvl

SourceX/storm_sdl_rw.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <SDL.h>
+
+#include "../SourceS/miniwin/misc.h"
+
+namespace dvl {
+
+/**
+ * @brief Creates a read-only SDL_RWops from a Storm file handle.
+ *
+ * Does not close the handle when it gets closed.
+ */
+SDL_RWops *SFileRw_FromStormHandle(HANDLE handle);
+
+} // namespace dvl