From 8722fe0080d312c469e2750f60644fa67753facd Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Thu, 13 Mar 2025 21:17:25 +0100
Subject: [PATCH] CD-ROM: Optimize Windows IOCTL disc change checking.

---
 src/cdrom/cdrom.c               |  4 ++++
 src/include/86box/cdrom.h       |  4 ++++
 src/qt/qt_winrawinputfilter.cpp | 27 ++++++++-------------------
 src/qt/win_cdrom_ioctl.c        | 16 ++++++++++++----
 4 files changed, 28 insertions(+), 23 deletions(-)

diff --git a/src/cdrom/cdrom.c b/src/cdrom/cdrom.c
index aea1afb94..c20e18db8 100644
--- a/src/cdrom/cdrom.c
+++ b/src/cdrom/cdrom.c
@@ -46,6 +46,7 @@
 cdrom_t cdrom[CDROM_NUM] = { 0 };
 
 int cdrom_interface_current;
+int cdrom_assigned_letters = 0;
 
 #ifdef ENABLE_CDROM_LOG
 int cdrom_do_log = ENABLE_CDROM_LOG;
@@ -2795,6 +2796,8 @@ cdrom_global_init(void)
 void
 cdrom_hard_reset(void)
 {
+    cdrom_assigned_letters = 0;
+
     for (uint8_t i = 0; i < CDROM_NUM; i++) {
         cdrom_t *dev = &cdrom[i];
 
@@ -2825,6 +2828,7 @@ cdrom_hard_reset(void)
             }
 
             dev->cd_status = CD_STATUS_EMPTY;
+            dev->host_letter = 0xff;
 
             if (strlen(dev->image_path) > 0) {
 #ifdef _WIN32
diff --git a/src/include/86box/cdrom.h b/src/include/86box/cdrom.h
index 7c028d7d6..805f08b10 100644
--- a/src/include/86box/cdrom.h
+++ b/src/include/86box/cdrom.h
@@ -335,6 +335,8 @@ typedef struct cdrom {
     uint8_t            subch_buffer[96];
 
     int                cdrom_sector_size;
+    /* Only used on Windows hosts for disc change notifications. */
+    uint8_t            host_letter;
 
     /* Needs some extra breathing space in case of overflows. */
     uint8_t            raw_buffer[4096];
@@ -437,6 +439,8 @@ extern int             cdrom_is_empty(const uint8_t id);
 extern void            cdrom_eject(const uint8_t id);
 extern void            cdrom_reload(const uint8_t id);
 
+extern int             cdrom_assigned_letters;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/qt/qt_winrawinputfilter.cpp b/src/qt/qt_winrawinputfilter.cpp
index cff9950b2..8a2841f97 100644
--- a/src/qt/qt_winrawinputfilter.cpp
+++ b/src/qt/qt_winrawinputfilter.cpp
@@ -157,27 +157,16 @@ WindowsRawInputFilter::~WindowsRawInputFilter()
 static void
 notify_drives(ULONG unitmask, int empty)
 {
-    char p[1024] = { 0 };
+    if (unitmask & cdrom_assigned_letters)  for (int i = 0; i < CDROM_NUM; i++) {
+        cdrom_t *dev = &(cdrom[i]);
 
-    for (int i = 0; i < 26; ++i) {
-        if (unitmask & (1 << i)) {
-            cdrom_t *dev = NULL;
-
-            sprintf(p, "ioctl://\\\\.\\%c:", 'A' + i);
-
-            for (int i = 0; i < CDROM_NUM; i++)
-                if (!stricmp(cdrom[i].image_path, p)) {
-                    dev = &(cdrom[i]);
-                    if (empty)
-                        cdrom_set_empty(dev);
-                    else
-                        cdrom_update_status(dev);
-                    // pclog("CD-ROM %i      : Drive notified of media %s\n",
-                          // dev->id, empty ? "removal" : "change");
-                }
+        if ((dev->host_letter != 0xff) &&
+            (unitmask & (1 << dev->host_letter))) {
+            if (empty)
+                cdrom_set_empty(dev);
+            else
+                cdrom_update_status(dev);
         }
-
-        unitmask = unitmask >> 1;
     }
 }
 
diff --git a/src/qt/win_cdrom_ioctl.c b/src/qt/win_cdrom_ioctl.c
index 621cf0b76..309f861e0 100644
--- a/src/qt/win_cdrom_ioctl.c
+++ b/src/qt/win_cdrom_ioctl.c
@@ -748,6 +748,11 @@ ioctl_close(void *local)
 
     log_close(ioctl->log);
     ioctl->log = NULL;
+
+    cdrom_assigned_letters &= ~(1 << ioctl->dev->host_letter);
+    ioctl->dev->host_letter = 0xff;
+
+    free(ioctl);
 }
 
 static void
@@ -788,19 +793,22 @@ ioctl_open(cdrom_t *dev, const char *drv)
     ioctl_t *ioctl = (ioctl_t *) calloc(1, sizeof(ioctl_t));
 
     if (ioctl != NULL) {
-        char n[1024]        = { 0 };
+        char n[1024]            = { 0 };
 
         sprintf(n, "CD-ROM %i IOCtl", dev->id + 1);
-        ioctl->log          = log_open(n);
+        ioctl->log              = log_open(n);
 
         memset(ioctl->path, 0x00, sizeof(ioctl->path));
 
         wsprintf(ioctl->path, L"%S", &(drv[8]));
         ioctl_log(ioctl->log, "Path is %S\n", ioctl->path);
 
-        ioctl->dev          = dev;
+        ioctl->dev              = dev;
 
-        dev->ops            = &ioctl_ops;
+        dev->ops                = &ioctl_ops;
+
+        dev->host_letter        = (drv[12] & 0xdf) - 0x41;
+        cdrom_assigned_letters |= (1 << dev->host_letter);
 
         ioctl_load(ioctl);
     }