Add the fe-image command and the TRS-80 JV3 file reader.

2025-10-31 11:17:01 -07:00 · 2020-09-18 00:53:39 +02:00
parent 3b02bc8cf1
commit ef3c9f3d03
9 changed files with 201 additions and 12 deletions
--- a/lib/imagereader/jv3imagereader.cc
+++ b/lib/imagereader/jv3imagereader.cc
@@ -0,0 +1,141 @@
+#include "globals.h"
+#include "flags.h"
+#include "dataspec.h"
+#include "sector.h"
+#include "sectorset.h"
+#include "imagereader/imagereader.h"
+#include "fmt/format.h"
+#include <algorithm>
+#include <iostream>
+#include <fstream>
+
+/* JV3 files are kinda weird. There's a fixed layout for up to 2901 sectors, which may appear
+ * in any order, followed by the same again for more sectors. To find the second data block
+ * you need to know the size of the first data block, which requires parsing it.
+ *
+ * https://www.tim-mann.org/trs80/dskspec.html
+ *
+ * typedef struct {
+ *   SectorHeader headers1[2901];
+ *   unsigned char writeprot;
+ *   unsigned char data1[];
+ *   SectorHeader headers2[2901];
+ *   unsigned char padding;
+ *   unsigned char data2[];
+ * } JV3;
+ *
+ * typedef struct {
+ *   unsigned char track;
+ *   unsigned char sector;
+ *   unsigned char flags;
+ * } SectorHeader;
+ */
+
+struct SectorHeader
+{
+	uint8_t track;
+	uint8_t sector;
+	uint8_t flags;
+};
+
+#define JV3_DENSITY     0x80  /* 1=dden, 0=sden */
+#define JV3_DAM         0x60  /* data address mark code; see below */
+#define JV3_SIDE        0x10  /* 0=side 0, 1=side 1 */
+#define JV3_ERROR       0x08  /* 0=ok, 1=CRC error */
+#define JV3_NONIBM      0x04  /* 0=normal, 1=short */
+#define JV3_SIZE        0x03  /* in used sectors: 0=256,1=128,2=1024,3=512
+                                 in free sectors: 0=512,1=1024,2=128,3=256 */
+
+#define JV3_FREE        0xFF  /* in track and sector fields of free sectors */
+#define JV3_FREEF       0xFC  /* in flags field, or'd with size code */
+
+static unsigned getSectorSize(uint8_t flags)
+{
+	if ((flags & JV3_FREEF) == JV3_FREEF)
+	{
+		switch (flags & JV3_SIZE)
+		{
+			case 0: return 512;
+			case 1: return 1024;
+			case 2: return 128;
+			case 3: return 256;
+		}
+	}
+	else
+	{
+		switch (flags & JV3_SIZE)
+		{
+			case 0: return 256;
+			case 1: return 128;
+			case 2: return 1024;
+			case 3: return 512;
+		}
+	}
+	Error() << "not reachable";
+}
+
+class Jv3ImageReader : public ImageReader
+{
+public:
+	Jv3ImageReader(const ImageSpec& spec):
+		ImageReader(spec)
+	{}
+
+	SectorSet readImage()
+	{
+        std::ifstream inputFile(spec.filename, std::ios::in | std::ios::binary);
+        if (!inputFile.is_open())
+            Error() << "cannot open input file";
+
+		inputFile.seekg( 0, std::ios::end);
+		unsigned inputFileSize = inputFile.tellg();
+		unsigned headerPtr = 0;
+		SectorSet sectors;
+		for (;;)
+		{
+			unsigned dataPtr = headerPtr + 2901*3 + 1;
+			if (dataPtr >= inputFileSize)
+				break;
+
+			for (unsigned i=0; i<2901; i++)
+			{
+				SectorHeader header = {0, 0, 0xff};
+				inputFile.seekg(headerPtr);
+				inputFile.read((char*) &header, 3);
+				unsigned sectorSize = getSectorSize(header.flags);
+				if ((header.flags & JV3_FREEF) != JV3_FREEF)
+				{
+					Bytes data(sectorSize);
+					inputFile.seekg(dataPtr);
+					inputFile.read((char*) data.begin(), sectorSize);
+
+					unsigned head = !!(header.flags & JV3_SIDE);
+                    std::unique_ptr<Sector>& sector = sectors.get(header.track, head, header.sector);
+                    sector.reset(new Sector);
+                    sector->status = Sector::OK;
+                    sector->logicalTrack = sector->physicalTrack = header.track;
+                    sector->logicalSide = sector->physicalSide = head;
+                    sector->logicalSector = header.sector;
+                    sector->data = data;
+				}
+
+				headerPtr += 3;
+				dataPtr += sectorSize;
+			}
+
+			/* dataPtr is now pointing at the beginning of the next chunk. */
+
+			headerPtr = dataPtr;
+		}
+
+        return sectors;
+	}
+};
+
+std::unique_ptr<ImageReader> ImageReader::createJv3ImageReader(
+	const ImageSpec& spec)
+{
+    return std::unique_ptr<ImageReader>(new Jv3ImageReader(spec));
+}
+
+