From a374f9f4b8138cbbf976d7f0fa81c5888a25e72d Mon Sep 17 00:00:00 2001
From: Asnivor <coding@asnitech.co.uk>
Date: Thu, 3 May 2018 15:33:30 +0100
Subject: [PATCH] ZXHawk: Some UPD ReadID improvements

---
 .../Hardware/Disk/NECUPD765.FDC.cs            | 32 +++++++++++++++++--
 .../SinclairSpectrum/Machine/SpectrumBase.cs  |  4 +--
 .../SinclairSpectrum/ZXSpectrum.Messaging.cs  |  7 +++-
 3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Hardware/Disk/NECUPD765.FDC.cs b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Hardware/Disk/NECUPD765.FDC.cs
index 60582674a8..4ab2c2d133 100644
--- a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Hardware/Disk/NECUPD765.FDC.cs
+++ b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Hardware/Disk/NECUPD765.FDC.cs
@@ -598,7 +598,7 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
                                     ActiveCommandParams.Cylinder++;
 
                                     // reset sector
-                                    ActiveCommandParams.Sector = 1;
+                                    ActiveCommandParams.Sector = sector.SectorID; // 1;
                                     ActiveDrive.SectorIndex = 0;
                                 }
                                 else
@@ -1598,6 +1598,12 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
                                 ActiveDrive.SectorIndex = 0;
                             }
 
+                            if (ActiveDrive.SectorIndex == 0 && ActiveDrive.Disk.DiskTracks[ActiveDrive.CurrentTrackID].Sectors.Length > 1)
+                            {
+                                // looks like readid always skips the first sector on a track
+                                ActiveDrive.SectorIndex++;
+                            }
+
                             // read the sector data
                             var data = track.Sectors[ActiveDrive.SectorIndex]; //.GetCHRN();
                             ResBuffer[RS_C] = data.TrackNumber;
@@ -2710,8 +2716,24 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
                     // set seek flag
                     ActiveDrive.SeekStatus = SEEK_SEEK;
 
-                    // immediate seek
-                    ActiveDrive.CurrentTrackID = CommBuffer[CM_C];                    
+                    if (ActiveDrive.CurrentTrackID == CommBuffer[CM_C])
+                    {
+                        // we are already on the correct track
+                        ActiveDrive.SectorIndex = 0;
+                    }
+                    else
+                    {
+                        // immediate seek
+                        ActiveDrive.CurrentTrackID = CommBuffer[CM_C];
+
+                        ActiveDrive.SectorIndex = 0;
+
+                        if (ActiveDrive.Disk.DiskTracks[ActiveDrive.CurrentTrackID].Sectors.Length > 1)
+                        {
+                            // always read the first sector
+                            //ActiveDrive.SectorIndex++;
+                        }
+                    }             
 
                     // skip execution mode and go directly to idle
                     // result is determined by SIS command
@@ -2773,6 +2795,10 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
                     ActiveDrive.TrackIndex = 0;
                     ActiveDrive.SectorIndex = 0;
 
+                    // recalibrate appears to always skip the first sector
+                    //if (ActiveDrive.Disk.DiskTracks[ActiveDrive.TrackIndex].Sectors.Length > 1)
+                        //ActiveDrive.SectorIndex++;
+
                     // set seek flag
                     ActiveDrive.SeekStatus = SEEK_RECALIBRATE;
 
diff --git a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/SpectrumBase.cs b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/SpectrumBase.cs
index 9d52641d6f..f2766502a7 100644
--- a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/SpectrumBase.cs
+++ b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/SpectrumBase.cs
@@ -204,14 +204,14 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
             Spectrum.IsLagFrame = !InputRead;
 
             // FDC debug
-            /*
+            
             if (UPDDiskDevice != null && UPDDiskDevice.writeDebug)
             {
                 // only write UPD log every second
                 if (FrameCount % 10 == 0)
                     System.IO.File.WriteAllText(UPDDiskDevice.outputfile, UPDDiskDevice.outputString);
             }
-            */
+            
         }
 
         #endregion
diff --git a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.Messaging.cs b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.Messaging.cs
index 737829434a..8c7f6baf14 100644
--- a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.Messaging.cs
+++ b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.Messaging.cs
@@ -129,7 +129,12 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
                 SendMessage(sb.ToString().TrimEnd('\n'), MessageCategory.Disk);
                 sb.Clear();
 
-                sb.Append("Detected Protection: " + Enum.GetName(typeof(ProtectionType), _machine.UPDDiskDevice.DiskPointer.Protection));
+                string protection = "None";
+                protection = Enum.GetName(typeof(ProtectionType), _machine.UPDDiskDevice.DiskPointer.Protection);
+                if (protection == "None")
+                    protection += " (OR UNKNOWN)";
+
+                sb.Append("Detected Protection: " + protection);
                 SendMessage(sb.ToString().TrimEnd('\n'), MessageCategory.Disk);
                 sb.Clear();