CD-ROM: Do not stop playing on a READ command that immediately terminates with an "illegal mode for this track" error, fixes track skipping in the Windows 95 CD Player.

src/cdrom/cdrom.c

@@ -2274,6 +2274,65 @@ cdrom_read_disc_info_toc(cdrom_t *dev, uint8_t *b,
     return ret;
 }
 
+static uint32_t
+cdrom_msf_to_lba(const int sector, const int ismsf,
+                 int cdrom_sector_type, const uint8_t vendor_type)
+{
+    int      pos = sector;
+    uint32_t lba;
+
+    if ((cdrom_sector_type & 0x0f) >= 0x08) {
+        mult               = cdrom_sector_type >> 4;
+        pos               /= mult;
+    }
+
+    if (ismsf) {
+        const int m = (pos >> 16) & 0xff;
+        const int s = (pos >> 8) & 0xff;
+        const int f = pos & 0xff;
+
+        lba = MSFtoLBA(m, s, f) - 150;
+    } else {
+        switch (vendor_type) {
+            case 0x00:
+                lba = pos;
+                break;
+            case 0x40: {
+                const int m = bcd2bin((pos >> 24) & 0xff);
+                const int s = bcd2bin((pos >> 16) & 0xff);
+                const int f = bcd2bin((pos >> 8) & 0xff);
+
+                lba = MSFtoLBA(m, s, f) - 150;
+                break;
+            } case 0x80:
+                lba = bcd2bin((pos >> 24) & 0xff);
+                break;
+            /* Never used values but the compiler complains. */
+            default:
+                lba = 0;
+        }
+    }
+
+    return lba;
+}
+
+int
+cdrom_is_track_audio(cdrom_t *dev, const int sector,
+                     const int ismsf, int cdrom_sector_type,
+                     const uint8_t vendor_type)
+{
+    int      audio = 0;
+    uint32_t lba   = cdrom_msf_to_lba(sector, ismsf,
+                                      cdrom_sector_type, vendor_type);
+
+    if (dev->ops->get_track_type)
+        audio = dev->ops->get_track_type(dev->local, lba);
+
+    audio        &= CD_TRACK_AUDIO;
+
+    return audio;
+}
+
 int
 cdrom_readsector_raw(cdrom_t *dev, uint8_t *buffer, const int sector, const int ismsf,
                      int cdrom_sector_type, const int cdrom_sector_flags,
@@ -2298,38 +2357,12 @@ cdrom_readsector_raw(cdrom_t *dev, uint8_t *buffer, const int sector, const int
         uint8_t *temp_b;
         uint8_t *b      = temp_b = buffer;
         int      audio  = 0;
-        uint32_t lba;
+        uint32_t lba    = cdrom_msf_to_lba(sector, ismsf,
+                                           cdrom_sector_type, vendor_type);
         int      mode2  = 0;
 
         *len = 0;
 
-        if (ismsf) {
-            const int m = (pos >> 16) & 0xff;
-            const int s = (pos >> 8) & 0xff;
-            const int f = pos & 0xff;
-
-            lba = MSFtoLBA(m, s, f) - 150;
-        } else {
-            switch (vendor_type) {
-                case 0x00:
-                    lba = pos;
-                    break;
-                case 0x40: {
-                    const int m = bcd2bin((pos >> 24) & 0xff);
-                    const int s = bcd2bin((pos >> 16) & 0xff);
-                    const int f = bcd2bin((pos >> 8) & 0xff);
-
-                    lba = MSFtoLBA(m, s, f) - 150;
-                    break;
-                } case 0x80:
-                    lba = bcd2bin((pos >> 24) & 0xff);
-                    break;
-                /* Never used values but the compiler complains. */
-                default:
-                    lba = 0;
-            }
-        }
-
         if (dev->ops->get_track_type)
             audio = dev->ops->get_track_type(dev->local, lba);
 

src/include/86box/cdrom.h

@@ -425,6 +425,8 @@ extern uint8_t         cdrom_mitsumi_audio_play(cdrom_t *dev, uint32_t pos, uint
 #endif
 extern uint8_t         cdrom_read_disc_info_toc(cdrom_t *dev, uint8_t *b,
                                                 const uint8_t track, const int type);
+extern int             cdrom_is_track_audio(cdrom_t *dev, const int sector, const int ismsf,
+                                            int cdrom_sector_type, const uint8_t vendor_type);
 extern int             cdrom_readsector_raw(cdrom_t *dev, uint8_t *buffer, const int sector, const int ismsf,
                                             int cdrom_sector_type, const int cdrom_sector_flags,
                                             int *len, const uint8_t vendor_type);

src/scsi/scsi_cdrom.c

@@ -2610,6 +2610,11 @@ scsi_cdrom_command(scsi_common_t *sc, const uint8_t *cdb)
                         dev->sector_len = 256;
                     dev->sector_pos = ((((uint32_t) cdb[1]) & 0x1f) << 16) |
                                       (((uint32_t) cdb[2]) << 8) | ((uint32_t) cdb[3]);
+                    if (cdrom_is_track_audio(dev->drv, dev->sector_pos, msf,
+                                             dev->sector_type, 0x00)) {
+                        scsi_cdrom_illegal_mode(dev);
+                        ret = 0;
+                    }                        
                     scsi_cdrom_log(dev->log, "READ (6):  Length: %i, LBA: %i\n",
                                    dev->sector_len, dev->sector_pos);
                     break;
@@ -2617,6 +2622,12 @@ scsi_cdrom_command(scsi_common_t *sc, const uint8_t *cdb)
                     dev->sector_len = (cdb[7] << 8) | cdb[8];
                     dev->sector_pos = (cdb[2] << 24) | (cdb[3] << 16) |
                                       (cdb[4] << 8) | cdb[5];
+                    if (cdrom_is_track_audio(dev->drv, dev->sector_pos, msf,
+                                             dev->sector_type, dev->use_cdb_9 ?
+                                             (cdb[9] & 0xc0) : 0x00)) {
+                        scsi_cdrom_illegal_mode(dev);
+                        ret = 0;
+                    }                        
                     scsi_cdrom_log(dev->log, "READ (10): Length: %i, LBA: %i\n",
                                    dev->sector_len, dev->sector_pos);
                     break;
@@ -2627,6 +2638,12 @@ scsi_cdrom_command(scsi_common_t *sc, const uint8_t *cdb)
                     dev->sector_pos = (((uint32_t) cdb[2]) << 24) |
                                       (((uint32_t) cdb[3]) << 16) |
                                       (((uint32_t) cdb[4]) << 8) | ((uint32_t) cdb[5]);
+                    if (cdrom_is_track_audio(dev->drv, dev->sector_pos, msf,
+                                             dev->sector_type, dev->use_cdb_9 ?
+                                             (cdb[9] & 0xc0) : 0x00)) {
+                        scsi_cdrom_illegal_mode(dev);
+                        ret = 0;
+                    }                        
                     scsi_cdrom_log(dev->log, "READ (12): Length: %i, LBA: %i\n",
                                    dev->sector_len, dev->sector_pos);
                     break;