Add support for the 83kB 5.25" Lanier format.

Author: davidgiven

arch/aeslanier/aeslanier.h

@@ -1,9 +1,19 @@
 #ifndef AESLANIER_H
 #define AESLANIER_H
 
+/* MFM:
+ * 
+ * Raw bits:
+ *    5    5    5    5    5    1    2    2
+ * 0101 0101 0101 0101 0101 0001 0010 0010
+ * 0 0  0 0  0 0  0 0  0 0  0 0  0 1  0 1
+ *        0         0         0         5
+ * Decoded bits.
+ */
+
 #define AESLANIER_RECORD_SEPARATOR 0x55555122
 #define AESLANIER_SECTOR_LENGTH 256
-#define AESLANIER_RECORD_SIZE (AESLANIER_SECTOR_LENGTH + 5)
+#define AESLANIER_RECORD_SIZE (AESLANIER_SECTOR_LENGTH + 4)
 
 extern std::unique_ptr<Decoder> createAesLanierDecoder(
     const DecoderProto& config);

arch/aeslanier5/aeslanier5.h

@@ -1,9 +1,19 @@
 #ifndef AESLANIER5_H
 #define AESLANIER5_H
 
-#define AESLANIER5_RECORD_SEPARATOR 0x55555122
-#define AESLANIER5_SECTOR_LENGTH 256
-#define AESLANIER5_RECORD_SIZE (AESLANIER5_SECTOR_LENGTH + 5)
+/* Format is FM:
+ *
+ *    a    a    a    a    f    b    e    f
+ * 1010 1010 1010 1010 1111 1011 1110 1111
+ *  0 0  0 0  0 0  0 0  1 1  0 1  1 0  1 1
+ *         0         0         d         b
+ * 
+ * However, note that this pattern is _not_ reversed...
+ */
+
+#define AESLANIER5_RECORD_SEPARATOR 0xaaaaaaaaaaaafbefLL
+#define AESLANIER5_SECTOR_LENGTH 151
+#define AESLANIER5_RECORD_SIZE (AESLANIER5_SECTOR_LENGTH + 3)
 
 extern std::unique_ptr<Decoder> createAesLanier5Decoder(
     const DecoderProto& config);

arch/aeslanier5/decoder.cc

@@ -12,7 +12,7 @@
 
 static const FluxPattern SECTOR_PATTERN(32, AESLANIER5_RECORD_SEPARATOR);
 
-/* This is actually M2FM, rather than MFM, but it our MFM/FM decoder copes fine
+/* This is actually FM, rather than MFM, but it our MFM/FM decoder copes fine
  * with it. */
 
 class AesLanier5Decoder : public Decoder
@@ -29,32 +29,45 @@ class AesLanier5Decoder : public Decoder
     {
         /* Skip ID mark (we know it's a AESLANIER5_RECORD_SEPARATOR). */
 
-        readRawBits(16);
+        readRawBits(SECTOR_PATTERN.length());
 
         const auto& rawbits = readRawBits(AESLANIER5_RECORD_SIZE * 16);
         const auto& bytes =
             decodeFmMfm(rawbits).slice(0, AESLANIER5_RECORD_SIZE);
         const auto& reversed = bytes.reverseBits();
 
-        _sector->logicalTrack = reversed[1];
+        uint8_t encodedTrack = reversed[0];
+        uint8_t encodedSector = reversed[1];
+
+        _sector->logicalTrack = encodedTrack >> 1;
         _sector->logicalSide = 0;
-        _sector->logicalSector = reversed[2];
+        _sector->logicalSector = encodedSector;
 
         /* Check header 'checksum' (which seems far too simple to mean much). */
 
         {
-            uint8_t wanted = reversed[3];
-            uint8_t got = reversed[1] + reversed[2];
+            uint8_t wanted = reversed[2];
+            uint8_t got = reversed[0] + reversed[1];
             if (wanted != got)
                 return;
         }
 
         /* Check data checksum, which also includes the header and is
          * significantly better. */
 
-        _sector->data = reversed.slice(1, AESLANIER5_SECTOR_LENGTH);
-        uint16_t wanted = reversed.reader().seek(0x101).read_le16();
-        uint16_t got = crc16ref(MODBUS_POLY_REF, _sector->data);
+        _sector->data = reversed.slice(3, AESLANIER5_SECTOR_LENGTH);
+        uint8_t wanted, got;
+        ByteReader br(_sector->data);
+        if ((encodedSector == 0) || (encodedSector == 8))
+        {
+            wanted = br.seek(17).read_8() + br.seek(150).read_8();
+            got = sumBytes(_sector->data.slice(0, 17)) + sumBytes(_sector->data.slice(18, 132));
+        }
+        else
+        {
+            wanted = br.seek(150).read_8();
+            got = sumBytes(_sector->data.slice(0, AESLANIER5_SECTOR_LENGTH-1));
+        }
         _sector->status = (wanted == got) ? Sector::OK : Sector::BAD_CHECKSUM;
     }
 };

doc/disk-aeslanier.md

@@ -32,15 +32,15 @@ based on what looks right. If anyone knows _anything_ about these disks,
 ## Options
 
   - Format variants:
-      - `8" format`: use the format found on 8" disks
-      - `5.25" format`: use the format found on 5.25" disks
+      - `8`: use the format found on 8" disks
+      - `5`: use the format found on 5.25" disks
 
 ## Examples
 
 To read:
 
-  - `fluxengine read aeslanier --8" format -s drive:0 -o aeslanier.img`
-  - `fluxengine read aeslanier --5.25" format -s drive:0 -o aeslanier.img`
+  - `fluxengine read aeslanier --8 -s drive:0 -o aeslanier.img`
+  - `fluxengine read aeslanier --5 -s drive:0 -o aeslanier.img`
 
 ## References
 

lib/data/fluxpattern.h

@@ -33,6 +33,11 @@ class FluxPattern : public FluxMatcher
 
     bool matches(const unsigned* intervals, FluxMatch& match) const override;
 
+    unsigned length() const
+    {
+        return _bits;
+    }
+
     unsigned intervals() const override
     {
         return _intervals.size();

src/formats/aeslanier.textpb

@@ -14,6 +14,8 @@ of nearly £50,000 in 2018!).
 processing software off twin 5.25" drive units, but apparently other software
 was available.
 
+**Note:** the following is wrong and needs to be updated.
+
 The disk format is exceptionally weird. They used 77 track, 32 sector, single-sided
 _hard_ sectored disks, where there were multiple index holes,
 indicating to the hardware where the sectors start. The encoding scheme
@@ -50,7 +52,7 @@ option_group {
 	comment: "$formats"
 
 	option {
-		name: '8" format'
+		name: '8'
 		comment: 'use the format found on 8" disks'
 		set_by_default: true
 
@@ -75,8 +77,8 @@ option_group {
 	}
 
 	option {
-		name: '5.25" format'
-		comment: 'use the format found on 5.25" disks'
+		name: '83'
+		comment: '83kB 5.25" 35-track 16-sector SSSD'
 
 		config {
 			decoder {

src/gui/fluxviewercontrol.cc

@@ -246,12 +246,13 @@ void FluxViewerControl::OnPaint(wxPaintEvent&)
             dc.SetTextForeground(*wxBLACK);
             for (auto& sector : trackdata->sectors)
             {
-                nanoseconds_t sr = sector->dataEndTime;
-                if (!sr)
-                    sr = sector->headerEndTime;
+                nanoseconds_t tl = sector->headerStartTime;
+                nanoseconds_t tr = sector->dataEndTime;
+                if (!tl && !sector->headerEndTime)
+                    tl = sector->dataStartTime;
 
-                int sp = sector->headerStartTime / _nanosecondsPerPixel;
-                int sw = (sr - sector->headerStartTime) / _nanosecondsPerPixel;
+                int sp = tl / _nanosecondsPerPixel;
+                int sw = (tr - tl) / _nanosecondsPerPixel;
 
                 wxRect rect = {x + sp, t1y - ch2, sw, ch};
                 bool hovered = rect.Contains(_mouseX, _mouseY);