Replaced buffered SDL_RWops wrapper with PHYSFS_setBuffer

This removes the buffered SDL_RWops functionality that was just added in
51b0c3239265ddee2d1bf445f873299cc8193ab9. We just call PHYSFS_setBuffer
instead.

Using the PhysicsFS buffer is a little bit slower, likely because it
operates at a lower level, but it is fast enough for our purposes.
Uncompressed music files loaded from ZIP files can start playing in
about 1-2 ms.

I've also landed a fix for the problem in SDL_mixer, which works even
better in any case: https://github.com/libsdl-org/SDL_mixer/pull/671

4 files changed, 13 insertions, 225 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f47cbf5b..b7cfe091 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -368,8 +368,6 @@ set(SRCS
     resources/wallpaper.h
     utils/base64.cpp
     utils/base64.h
-    utils/bufferedrwops.c
-    utils/bufferedrwops.h
     utils/copynpaste.cpp
     utils/copynpaste.h
     utils/dtor.h
diff --git a/src/utils/bufferedrwops.c b/src/utils/bufferedrwops.c
deleted file mode 100644
index e12f8b5b..00000000
--- a/src/utils/bufferedrwops.c
+++ /dev/null
@@ -1,184 +0,0 @@
-/*
- * Buffered SDL_RWops implementation
- * Copyright (C) 2025  Thorbjørn Lindeijer
- *
- * Written as part of a conversation between a human and an AI assistant
- * on GitHub Copilot Chat.
- *
- * This code is released into the public domain. You may use it freely
- * for any purpose, including commercial applications.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
- * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
- * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
- * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
- * OTHER DEALINGS IN THE SOFTWARE.
- */
-
-#include "bufferedrwops.h"
-
-#include <string.h>
-
-#define BUFFER_SIZE 2048
-
-typedef struct BufferedRWops {
-    SDL_RWops* source;          // The underlying RWops we're wrapping
-    size_t bufferPos;           // Current position within buffer
-    size_t bufferFill;          // How much valid data is in buffer
-    Sint64 virtualPos;          // Current virtual stream position
-    Uint8 buffer[BUFFER_SIZE];  // Our read-ahead buffer
-} BufferedRWops;
-
-static Sint64 SDLCALL buffered_size(SDL_RWops* context) {
-    BufferedRWops* br = (BufferedRWops*)context->hidden.unknown.data1;
-    return SDL_RWsize(br->source);
-}
-
-static Sint64 SDLCALL buffered_seek(SDL_RWops* context, Sint64 offset, int whence) {
-    BufferedRWops* br = (BufferedRWops*)context->hidden.unknown.data1;
-    Sint64 newPos;
-
-    // Calculate new position
-    switch (whence) {
-        case RW_SEEK_SET:
-            newPos = offset;
-            break;
-        case RW_SEEK_CUR:
-            newPos = br->virtualPos + offset;
-            break;
-        case RW_SEEK_END: {
-            Sint64 size = SDL_RWsize(br->source);
-            if (size < 0) return -1;
-            newPos = size + offset;
-            break;
-        }
-        default:
-            SDL_SetError("Invalid whence value");
-            return -1;
-    }
-
-    if (newPos < 0) {
-        SDL_SetError("Attempt to seek before start of file");
-        return -1;
-    }
-
-    // Check if new position is within our buffer
-    Sint64 bufferStart = br->virtualPos - br->bufferPos;
-    Sint64 bufferEnd = bufferStart + br->bufferFill;
-
-    if (newPos >= bufferStart && newPos < bufferEnd) {
-        // Position is within buffer - just update buffer position
-        br->bufferPos = (size_t)(newPos - bufferStart);
-    } else {
-        // Position is outside buffer - need to seek in source
-        if (SDL_RWseek(br->source, newPos, RW_SEEK_SET) < 0) {
-            return -1;
-        }
-        br->bufferPos = 0;
-        br->bufferFill = 0;
-    }
-
-    br->virtualPos = newPos;
-    return newPos;
-}
-
-static size_t SDLCALL buffered_read(SDL_RWops* context, void* dst, size_t size, size_t maxnum) {
-    BufferedRWops* br = (BufferedRWops*)context->hidden.unknown.data1;
-    size_t total = size * maxnum;
-    size_t copied = 0;
-
-    // Handle single byte reads separately since it is a common case when
-    // SDL_mixer uses stb_vorbis.
-    if (total == 1 && br->bufferPos < br->bufferFill) {
-        *(Uint8*)dst = br->buffer[br->bufferPos];
-        ++br->bufferPos;
-        ++br->virtualPos;
-        return 1;
-    }
-
-    while (copied < total) {
-        size_t remaining = total - copied;
-
-        // If buffer is empty or exhausted, try to fill it
-        if (br->bufferPos >= br->bufferFill) {
-            // If we want to read more than the buffer size, bypass the buffer
-            if (remaining >= BUFFER_SIZE) {
-                size_t read = SDL_RWread(br->source, dst + copied, 1, remaining);
-                copied += read;
-                br->virtualPos += read;
-                break;  // Nothing more to read
-            }
-
-            br->bufferPos = 0;
-            br->bufferFill = SDL_RWread(br->source, br->buffer, 1, BUFFER_SIZE);
-
-            if (br->bufferFill == 0)
-                break; // EOF or error
-        }
-
-        // Copy what we can from the buffer
-        size_t available = br->bufferFill - br->bufferPos;
-        size_t toCopy = remaining < available ? remaining : available;
-
-        memcpy(dst + copied, br->buffer + br->bufferPos, toCopy);
-        br->bufferPos += toCopy;
-        copied += toCopy;
-        br->virtualPos += toCopy;
-    }
-
-    return copied / size;
-}
-
-static size_t SDLCALL buffered_write(SDL_RWops* context, const void* ptr, size_t size, size_t num) {
-    SDL_SetError("Write operations not supported on buffered read-only RWops");
-    return 0;
-}
-
-static int SDLCALL buffered_close(SDL_RWops* context) {
-    if (context) {
-        BufferedRWops* br = (BufferedRWops*)context->hidden.unknown.data1;
-        if (br) {
-            if (br->source) {
-                SDL_RWclose(br->source);
-            }
-            SDL_free(br);
-        }
-        SDL_FreeRW(context);
-    }
-    return 0;
-}
-
-SDL_RWops* createBufferedRWops(SDL_RWops* source) {
-    if (!source) {
-        SDL_SetError("NULL source RWops");
-        return NULL;
-    }
-
-    BufferedRWops* br = (BufferedRWops*)SDL_malloc(sizeof(BufferedRWops));
-    if (!br) {
-        SDL_SetError("Out of memory");
-        return NULL;
-    }
-
-    br->source = source;
-    br->bufferPos = 0;
-    br->bufferFill = 0;
-    br->virtualPos = 0;
-
-    SDL_RWops* rw = SDL_AllocRW();
-    if (!rw) {
-        SDL_free(br);
-        return NULL;
-    }
-
-    rw->size = buffered_size;
-    rw->seek = buffered_seek;
-    rw->read = buffered_read;
-    rw->write = buffered_write;
-    rw->close = buffered_close;
-    rw->hidden.unknown.data1 = br;
-
-    return rw;
-}
diff --git a/src/utils/bufferedrwops.h b/src/utils/bufferedrwops.h
deleted file mode 100644
index bba29467..00000000
--- a/src/utils/bufferedrwops.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/*
- * Buffered SDL_RWops implementation
- * Copyright (C) 2025  Thorbjørn Lindeijer
- *
- * Written as part of a conversation between a human and an AI assistant
- * on GitHub Copilot Chat.
- *
- * This code is released into the public domain. You may use it freely
- * for any purpose, including commercial applications.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
- * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
- * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
- * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
- * OTHER DEALINGS IN THE SOFTWARE.
- */
-
-#include "SDL.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-SDL_RWops* createBufferedRWops(SDL_RWops* source);
-
-#ifdef __cplusplus
-}
-#endif
diff --git a/src/utils/filesystem.h b/src/utils/filesystem.h
index 0363cd22..3474e7c4 100644
--- a/src/utils/filesystem.h
+++ b/src/utils/filesystem.h
@@ -23,7 +23,6 @@
 // Suppress deprecation warnings for PHYSFS_getUserDir
 #define PHYSFS_DEPRECATED
 
-#include "utils/bufferedrwops.h"
 #include "utils/physfsrwops.h"
 
 #include <optional>
@@ -267,18 +266,23 @@ inline SDL_RWops *openRWops(const std::string &path)
 /**
  * Creates a buffered SDL_RWops.
  *
- * Used to workaround a performance issue when SDL_mixer is using stb_vorbis.
- * The overhead of calling PHYSFS_readBytes each time is too high because
- * stb_vorbis requests the file one byte at a time.
+ * Used to workaround a performance issue when SDL_mixer is using stb_vorbis,
+ * in which case the file is read one byte at a time.
  *
  * See https://github.com/libsdl-org/SDL_mixer/issues/670
  */
-inline SDL_RWops *openBufferedRWops(const std::string &path)
+inline SDL_RWops *openBufferedRWops(const std::string &path,
+                                    PHYSFS_uint64 bufferSize = 2048)
 {
-    auto rw = PHYSFSRWOPS_openRead(path.c_str());
-    if (auto buffered = createBufferedRWops(rw))
-        return buffered;
-    return rw;
+    if (auto file = PHYSFS_openRead(path.c_str()))
+    {
+        PHYSFS_setBuffer(file, bufferSize);
+        if (auto rw = PHYSFSRWOPS_makeRWops(file))
+            return rw;
+        else
+            PHYSFS_close(file);
+    }
+    return nullptr;
 }
 
 inline void *loadFile(const std::string &path, size_t &datasize)