From 9601cf683fbfce4ec6e18350037a69309cb9871a Mon Sep 17 00:00:00 2001
From: Thomas Daede <daede003@umn.edu>
Date: Mon, 15 Aug 2022 22:49:44 -0700
Subject: [PATCH] D88: Support multiple sector sizes in a single track.

---
 arch/ibm/encoder.cc               | 15 +++++++++++++++
 lib/image.cc                      |  4 ++--
 lib/image.h                       |  3 ++-
 lib/imagereader/d88imagereader.cc |  7 +------
 4 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/arch/ibm/encoder.cc b/arch/ibm/encoder.cc
index 73eb48971..cbc8a8c73 100644
--- a/arch/ibm/encoder.cc
+++ b/arch/ibm/encoder.cc
@@ -215,6 +215,17 @@ class IbmEncoder : public AbstractEncoder
         bool first = true;
         for (const auto& sectorData : sectors)
         {
+            if (image.getGeometry().variableSectorSize)
+            {
+                sectorSize = 0;
+                int s = sectorData->data.size() >> 7;
+                while (s > 1)
+                {
+                    s >>= 1;
+                    sectorSize += 1;
+                }
+            }
+
             if (!first)
                 writeFillerRawBytes(trackdata.gap3(), gapFill);
             first = false;
@@ -274,6 +285,10 @@ class IbmEncoder : public AbstractEncoder
 
                 Bytes truncatedData =
                     sectorData->data.slice(0, trackdata.sector_size());
+                if (image.getGeometry().variableSectorSize) {
+                    truncatedData = sectorData->data;
+                }
+
                 bw += truncatedData;
                 uint16_t crc = crc16(CCITT_POLY, data);
                 bw.write_be16(crc);
diff --git a/lib/image.cc b/lib/image.cc
index d8b9ede62..85180bd9c 100644
--- a/lib/image.cc
+++ b/lib/image.cc
@@ -37,7 +37,7 @@ std::shared_ptr<Sector> Image::put(unsigned track, unsigned side, unsigned secto
 	return sector;
 }
 
-void Image::calculateSize()
+void Image::calculateSize(bool variableSectorSize)
 {
 	_geometry = {};
 	unsigned maxSector = 0;
@@ -53,6 +53,6 @@ void Image::calculateSize()
 			_geometry.sectorSize = std::max(_geometry.sectorSize, (unsigned)sector->data.size());
 		}
 	}
+	_geometry.variableSectorSize = variableSectorSize;
 	_geometry.numSectors = maxSector - _geometry.firstSector + 1;
 }
-
diff --git a/lib/image.h b/lib/image.h
index 8c1d599ca..ba6610565 100644
--- a/lib/image.h
+++ b/lib/image.h
@@ -9,6 +9,7 @@ struct Geometry
 	unsigned numSectors = 0;
 	unsigned sectorSize = 0;
 	bool irregular = false;
+	bool variableSectorSize = false;
 };
 
 class Image
@@ -37,7 +38,7 @@ class Image
 	};
 
 public:
-	void calculateSize();
+	void calculateSize(bool variableSectorSize = false);
 
 	std::shared_ptr<const Sector> get(unsigned track, unsigned side, unsigned sectorId) const;
 	std::shared_ptr<Sector> put(unsigned track, unsigned side, unsigned sectorId);
diff --git a/lib/imagereader/d88imagereader.cc b/lib/imagereader/d88imagereader.cc
index b262692d1..91009c328 100644
--- a/lib/imagereader/d88imagereader.cc
+++ b/lib/imagereader/d88imagereader.cc
@@ -181,11 +181,6 @@ class D88ImageReader : public ImageReader
                         }
                     }
                 }
-                else if (trackSectorSize != sectorSize)
-                {
-                    Error() << "D88: multiple sector sizes per track are "
-                               "currently unsupported";
-                }
                 Bytes data(sectorSize);
                 inputFile.read((char*)data.begin(), data.size());
                 const auto& sector = image->put(track, head, sectorId);
@@ -207,7 +202,7 @@ class D88ImageReader : public ImageReader
             }
         }
 
-        image->calculateSize();
+        image->calculateSize(true);
         const Geometry& geometry = image->getGeometry();
         Logger() << fmt::format("D88: read {} tracks, {} sides",
             geometry.numTracks,