From f3d7cd9dd7ab51c7d994fd676991f7a53a5d54ac Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Mon, 15 Jul 2024 01:45:35 +0200
Subject: [PATCH] cdromdrive: add support for raw CD images.

---
 devices/storage/cdromdrive.cpp | 30 ++++++++++++++++++++++++++++--
 devices/storage/cdromdrive.h   |  2 ++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/devices/storage/cdromdrive.cpp b/devices/storage/cdromdrive.cpp
index 6666467..19839f3 100644
--- a/devices/storage/cdromdrive.cpp
+++ b/devices/storage/cdromdrive.cpp
@@ -30,12 +30,15 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include <cstring>
 #include <string>
 
-CdromDrive::CdromDrive() : BlockStorageDevice(31, 2048, 0xfffffffe) {
+CdromDrive::CdromDrive() : BlockStorageDevice(31, CDR_STD_DATA_SIZE, 0xfffffffe) {
     this->is_writeable = false;
 }
 
 void CdromDrive::insert_image(std::string filename) {
-    this->set_host_file(filename);
+    if (this->set_host_file(filename) < 0)
+        ABORT_F("Could not open CD-ROM image file, %s", filename.c_str());
+
+    this->detect_raw_image();
 
     // create single track descriptor
     this->tracks[0]  = {1, /*.trk_num*/ 0x14, /*.adr_ctrl*/ 0 /*.start_lba*/};
@@ -46,6 +49,29 @@ void CdromDrive::insert_image(std::string filename) {
         static_cast<uint32_t>(this->size_blocks + 1) /*.start_lba*/};
 }
 
+bool CdromDrive::detect_raw_image() {
+    uint8_t block_hdr[16];
+
+    // let's see if the image data starts with the Mode 1/2 sync pattern
+    this->img_file.read(block_hdr, 0, sizeof(block_hdr));
+
+    for (int i = 1; i <= 10; i++)
+        if (block_hdr[i] != 0xFF)
+            return false;
+
+    if (block_hdr[0] != 0 || block_hdr[11] != 0)
+        return false;
+
+    // for now, we only support Mode 1 images
+    if (block_hdr[15] == 1) {
+        this->set_block_size(2352);
+        this->data_offset = 16;
+        return true;
+    }
+
+    return false;
+}
+
 static char cdrom_vendor_dingus_id[] = "DINGUS  ";
 static char cdrom_product_id[]  = "DINGUS CD-ROM   ";
 static char cdrom_revision_id[] = "1.0 ";
diff --git a/devices/storage/cdromdrive.h b/devices/storage/cdromdrive.h
index f487827..a01d6b1 100644
--- a/devices/storage/cdromdrive.h
+++ b/devices/storage/cdromdrive.h
@@ -46,6 +46,7 @@ typedef struct {
 
 #define CDROM_MAX_TRACKS    100
 #define LEAD_OUT_TRK_NUM    0xAA
+#define CDR_STD_DATA_SIZE   2048
 
 class CdromDrive : public BlockStorageDevice {
 public:
@@ -71,6 +72,7 @@ protected:
     std::function<void(uint8_t, uint8_t)>  set_error;
     uint8_t hex_to_bcd(const uint8_t val);
     AddrMsf lba_to_msf(const int lba);
+    bool    detect_raw_image();
 
     TrackDescriptor tracks[CDROM_MAX_TRACKS];
     int             num_tracks;