flex floppy dsk: rewrite to be based on the wd177x dsk format

This now works with both single density and double density floppy disks, and
dynamically identifies boot sector IDs required for 6800 booting, and supports
writing back to the 'dsk' image files.

src/lib/formats/flex_dsk.cpp

@@ -4,12 +4,21 @@
  * flex_dsk.c  -  FLEX compatible disk images
  *
  *  Created on: 24/06/2014
+ *
+ * TODO This format does not yet handle double density disks with a single
+ * density track 0. FLEX DSK files are generally 'fixed' to have a consistent
+ * number of sectors per track which makes them easier to work with and gains
+ * more storage space, and tools and emulators generally only work with these
+ * formats. For now use single density disks, or patch the ROM to load the
+ * boot sector(s) in double density and patch the drivers to use double
+ * density on track zero. Drivers developed for emulators commonly have other
+ * issues and need work anyway.
  */
 
-	#include "emu.h" // logerror
 #include "flex_dsk.h"
+#include "formats/imageutl.h"
 
-flex_format::flex_format()
+flex_format::flex_format() : wd177x_format(formats)
 {
 }
 
@@ -28,80 +37,310 @@ const char *flex_format::extensions() const
 	return "dsk";
 }
 
-bool flex_format::supports_save() const
-{
-	return true;
-}
-
 int flex_format::identify(io_generic *io, uint32_t form_factor)
 {
-	io_generic_read(io, &info, 256 * 2, sizeof(struct sysinfo_sector));
+	int type = find_size(io, form_factor);
 
-	if(((info.last_trk+1) * info.last_sec) * 256 == io_generic_size(io))
+	if (type != -1)
-	{
+		return 75;
-		osd_printf_verbose("flex_dsk: %i tracks, %i sectors\n",info.last_trk+1,info.last_sec);
-		return 100;
-	}
 	return 0;
 }
 
-bool flex_format::load(io_generic *io, uint32_t form_factor, floppy_image *image)
+int flex_format::find_size(io_generic *io, uint32_t form_factor)
 {
-	int spt = info.last_sec;
+	uint64_t size = io_generic_size(io);
-	int bps = 256;
+	uint8_t boot0[256], boot1[256];
-	int cell_count = (form_factor == floppy_image::FF_525) ? 50000 : 100000;
-	int offset = 0;
-	int head_num = 1;
-	int total_tracks = info.last_trk+1;
-	bool double_sided = false;
 
-	if(total_tracks == 40 && spt == 36)
+	// Look at the boot sector.
-		double_sided = true;
+	// Density, sides, link??
-	if(total_tracks == 77 && spt == 30)
+	io_generic_read(io, &boot0, 256 * 0, sizeof(boot0));
-		double_sided = true;
+	io_generic_read(io, &boot1, 256 * 1, sizeof(boot1));
-	if(total_tracks == 80 && spt == 40)  // 800kB
+	// Look at the system information sector.
-		double_sided = true;
+	io_generic_read(io, &info, 256 * 2, sizeof(struct sysinfo_sector));
-	if(total_tracks == 80 && spt == 72)  // 1.44MB
-		double_sided = true;
-	if(spt >= 20)
-		double_sided = true;
 
-	if(double_sided)
+	LOG_FORMATS("FLEX floppy dsk size %d %d %d\n", (uint32_t)size, (uint32_t)size / 256, (uint32_t)size % 256);
+
+	LOG_FORMATS(" boot0:");
+	for (int i = 0; i < 16; i++) {
+	  LOG_FORMATS(" %02x", boot0[i]);
+	}
+	LOG_FORMATS("\n");
+
+	LOG_FORMATS(" boot1:");
+	for (int i = 0; i < 16; i++) {
+	  LOG_FORMATS(" %02x", boot1[i]);
+	}
+	LOG_FORMATS("\n");
+
+
+	// Check that the 'unused' area is actually unused.
+	LOG_FORMATS(" unused1:");
+	for (int i = 0; i < sizeof(info.unused1); i++) {
+	  LOG_FORMATS(" %02x", info.unused1[i]);
+	}
+	LOG_FORMATS("\n");
+
+	LOG_FORMATS(" disk_name: \"");
+	for (int i = 0; i < sizeof(info.disk_name); i++) {
+	  uint8_t ch = info.disk_name[i];
+	  if (ch < 0x20 || ch > 0x7f) {
+		LOG_FORMATS("[%02x]", ch);
+	  } else {
+		LOG_FORMATS("%c", ch);
+	  }
+	}
+	if (info.disk_ext[0] || info.disk_ext[1] || info.disk_ext[2]) {
+	  LOG_FORMATS(".");
+	  for (int i = 0; i < sizeof(info.disk_name); i++) {
+	    uint8_t ch = info.disk_name[i];
+	    if (ch < 0x20 || ch > 0x7f) {
+	      LOG_FORMATS("[%02x]", ch);
+	    } else {
+	      LOG_FORMATS("%c", ch);
+	    }
+	  }
+	}
+	LOG_FORMATS("\"\n");
+
+	LOG_FORMATS(" fc_start_trk %d, fc_start_sec %d\n", info.fc_start_trk, info.fc_start_sec);
+	LOG_FORMATS(" fc_end_trk: %d, fc_end_sec: %d\n", info.fc_end_trk, info.fc_end_sec);
+	LOG_FORMATS(" free: %02x %02x\n", info.free[0], info.free[0]);
+
+	LOG_FORMATS(" month %d day %d year %d\n", info.month, info.day, info.year);
+	LOG_FORMATS(" last_trk %d, last_sec %d\n", info.last_trk, info.last_sec);
+
+	LOG_FORMATS(" unused2:");
+	for (int i = 0; i < 16; i++) {
+	  LOG_FORMATS(" %02x", info.unused2[i]);
+	}
+	LOG_FORMATS("\n");
+
+#if 0
+	// Check that the first 'unused' area is zero filled.
+	// Unfortunately an occasional dsk image has non-zero values here.
+	for (int i = 0; i < sizeof(info.unused1); i++)
+		if (info.unused1[i] != 0) return -1;
+#endif
+
+	// Consistency checks.
+	if (info.fc_start_trk > info.last_trk || info.fc_end_trk > info.last_trk)
+		return -1;
+	if (info.fc_start_sec > info.last_sec || info.fc_end_sec > info.last_sec)
+		return -1;
+	if (info.month < 1 || info.month > 12 || info.day < 1 || info.day > 31)
+		return -1;
+
+	// FLEX sector numbers start at one generally, however the 6800 ROM
+	// boot loaders load the boot code from track zero, side zero,
+	// starting at sector zero. The boot code attempts to read multiple
+	// sectors and a gap in the sector numbering appears to be used to
+	// terminate the sequence. So if only one sector is to be loaded then
+	// the sector numbering is 0, 2, 3, .... If two sectors are to be
+	// loaded then the sector numbering is 0, 1, 3, 4 ... The boot loaders
+	// for 6809 FLEX systems appear to load from sector one so do not have
+	// this inconsistency to handle.
+	boot0_sector_id = 1;
+	boot1_sector_id = 2;
+
+	// This floppy format uses a strategy of looking for 6800 boot code to
+	// set the numbering of the first two sectors. If this is shown to not
+	// be practical in some common cases then a separate format variant
+	// might be needed.
+	if (boot0[0] == 0x8e && boot0[3] == 0x20)
 	{
-		spt = spt / 2;
+		// Found a 6800 stack load and branch, looks like a 6800 boot sector.
-		head_num = 2;
+		boot0_sector_id = 0;
+
+		// Look for a link to the next sector, normal usage.
+		if (boot1[0] != 0 || boot1[1] != 3)
+		{
+			// If not then assume it is a boot sector.
+			boot1_sector_id = 1;
+		}
+	}
+	LOG_FORMATS(" boot sector ids: %d %d\n",  boot0_sector_id, boot1_sector_id);
+
+	for(int i=0; formats[i].form_factor; i++) {
+		const format &f = formats[i];
+		if(form_factor != floppy_image::FF_UNKNOWN && form_factor != f.form_factor)
+			continue;
+
+		if(size != (uint64_t)compute_track_size(f) * f.track_count * f.head_count)
+			continue;
+
+		// Check consistency with the sysinfo record sector.
+		if (f.track_count != info.last_trk + 1)
+			continue;
+
+		if (f.sector_count * f.head_count != info.last_sec)
+			continue;
+
+		return i;
+	}
+	return -1;
 }
 
-	for(int track=0; track < total_tracks; track++)
+// FLEX numbers sectors on the second side of a track continuing from the
-		for(int head=0;head < head_num;head++)
+// first side which is a variation not handled by the generic code.
+//
+// FLEX generally numbers sectors starting at 1, however the 6800 boot sectors
+// are numbers starting at zero.
+//
+void flex_format::build_sector_description(const format &f, uint8_t *sectdata, desc_s *sectors, int track, int head) const
 {
-			desc_pc_sector sects[80];
+	if(f.sector_base_id == -1) {
-			uint8_t sect_data[20000];
+		for(int i=0; i<f.sector_count; i++) {
-			int sdatapos = 0;
+			int cur_offset = 0;
-			for(int i=0; i<spt; i++)
+			for(int j=0; j<f.sector_count; j++)
-			{
+				if(f.per_sector_id[j] < f.per_sector_id[i])
-				sects[i].track       = track;
+					cur_offset += f.sector_base_size ? f.sector_base_size : f.per_sector_size[j];
-				sects[i].head        = head;  // no side select?
+			sectors[i].data = sectdata + cur_offset;
-				if(head == 0)
+			sectors[i].size = f.sector_base_size ? f.sector_base_size : f.per_sector_size[i];
-					sects[i].sector      = i+1;
+			uint8_t sector_id = f.per_sector_id[i];
+			if (track == 0 && head == 0 && sector_id <= 2) {
+				if (sector_id == 0)
+					sector_id = boot0_sector_id;
 				else
-					sects[i].sector      = i+1+spt;
+					sector_id = boot1_sector_id;
-				sects[i].actual_size = bps;
-				sects[i].size        = 1;
-				sects[i].deleted     = false;
-				sects[i].bad_crc     = false;
-				sects[i].data        = &sect_data[sdatapos];
-				io_generic_read(io, sects[i].data, offset, bps);
-				offset += bps;
-				sdatapos += bps;
 			}
-			// gap sizes unverified
+			sectors[i].sector_id = f.sector_count * head + sector_id;
-			if(total_tracks == 35 && spt == 18 && (track >= 1 && track <= 2))  // handle Gimix Flex 3.6 disk image, which the boot sector loads tracks 1 and 2 as MFM
+		}
-				build_wd_track_mfm(track, head, image, cell_count*2, spt, sects, 50, 32, 22);
+	} else {
+		int cur_offset = 0;
+		for(int i=0; i<f.sector_count; i++) {
+			sectors[i].data = sectdata + cur_offset;
+			sectors[i].size = f.sector_base_size ? f.sector_base_size : f.per_sector_size[i];
+			cur_offset += sectors[i].size;
+			uint8_t sector_id = i + f.sector_base_id;
+			if (track == 0 && head == 0 && i < 2) {
+				if (i == 0)
+					sector_id = boot0_sector_id;
 				else
-				build_wd_track_fm(track, head, image, cell_count, spt, sects, 24, 16, 11);
+					sector_id = boot1_sector_id;
 			}
-	return true;
+			sectors[i].sector_id = f.sector_count * head + sector_id;
 		}
+	}
+}
+
+// For FLEX just use track 1 rather than the generic code that looks a track
+// 0. This is enough to avoid the odd sector numbering for the boot sectors,
+// while following the generic code.
+void flex_format::check_compatibility(floppy_image *image, std::vector<int> &candidates)
+{
+	uint8_t bitstream[500000/8];
+	uint8_t sectdata[50000];
+	desc_xs sectors[256];
+	int track_size;
+
+	// Extract the sectors
+	generate_bitstream_from_track(1, 0, formats[candidates[0]].cell_size, bitstream, track_size, image);
+
+	switch (formats[candidates[0]].encoding)
+	{
+	case floppy_image::FM:
+		extract_sectors_from_bitstream_fm_pc(bitstream, track_size, sectors, sectdata, sizeof(sectdata));
+		break;
+	case floppy_image::MFM:
+		extract_sectors_from_bitstream_mfm_pc(bitstream, track_size, sectors, sectdata, sizeof(sectdata));
+		break;
+	}
+
+	// Check compatibility with every candidate, copy in-place
+	int *ok_cands = &candidates[0];
+	for(unsigned int i=0; i != candidates.size(); i++) {
+		const format &f = formats[candidates[i]];
+		int ns = 0;
+		for(int j=0; j<256; j++)
+			if(sectors[j].data) {
+				int sid;
+				if(f.sector_base_id == -1) {
+					for(sid=0; sid < f.sector_count; sid++)
+						if(f.per_sector_id[sid] == j)
+							break;
+				} else
+					sid = j - f.sector_base_id;
+				if(sid < 0 || sid > f.sector_count)
+					goto fail;
+				if(f.sector_base_size) {
+					if(sectors[j].size != f.sector_base_size)
+						goto fail;
+				} else {
+					if(sectors[j].size != f.per_sector_size[sid])
+						goto fail;
+				}
+				ns++;
+			}
+		if(ns == f.sector_count)
+			*ok_cands++ = candidates[i];
+	fail:
+		;
+	}
+	candidates.resize(ok_cands - &candidates[0]);
+}
+
+const flex_format::format flex_format::formats[] = {
+	{ // 87.5K 5 1/4 inch single density - gaps unverified
+		floppy_image::FF_525, floppy_image::SSSD, floppy_image::FM,
+		4000, 10, 35, 1, 256, {}, 1, {}, 40, 16, 11
+	},
+	{ // 100K 5 1/4 inch single density - gaps unverified
+		floppy_image::FF_525, floppy_image::SSSD, floppy_image::FM,
+		4000, 10, 40, 1, 256, {}, 1, {}, 40, 16, 11
+	},
+	{ // 200K 5 1/4 inch single density - gaps unverified
+		floppy_image::FF_525, floppy_image::SSSD, floppy_image::FM,
+		4000, 10, 80, 1, 256, {}, 1, {}, 40, 16, 11
+	},
+	{ // 175K 5 1/4 inch single density - gaps unverified
+		floppy_image::FF_525, floppy_image::DSSD, floppy_image::FM,
+		4000, 10, 35, 2, 256, {}, 1, {}, 40, 16, 11
+	},
+	{ // 200K 5 1/4 inch single density - gaps unverified
+		floppy_image::FF_525, floppy_image::DSSD, floppy_image::FM,
+		4000, 10, 40, 2, 256, {}, 1, {}, 40, 16, 11
+	},
+	{ // 400K 5 1/4 inch single density - gaps unverified
+		floppy_image::FF_525, floppy_image::DSSD, floppy_image::FM,
+		4000, 10, 80, 2, 256, {}, 1, {}, 40, 16, 11
+	},
+	{ // 320K 5 1/4 inch double density - gaps unverified
+		floppy_image::FF_525, floppy_image::SSDD, floppy_image::MFM,
+		2000, 18, 40, 1, 256, {}, 1, {}, 80, 22, 24
+	},
+	{ // 320K 5 1/4 inch double density - gaps unverified
+		floppy_image::FF_525, floppy_image::DSDD, floppy_image::MFM,
+		2000, 18, 40, 2, 256, {}, 1, {}, 80, 22, 24
+	},
+	{ // 360K 5 1/4 inch quad density - gaps unverified
+		floppy_image::FF_525, floppy_image::SSQD, floppy_image::MFM,
+		2000, 18, 80, 1, 256, {}, 1, {}, 80, 22, 24
+	},
+	{ // 720K 5 1/4 inch quad density - gaps unverified
+		floppy_image::FF_525, floppy_image::DSQD, floppy_image::MFM,
+		2000, 18, 80, 2, 256, {}, 1, {}, 80, 22, 24
+	},
+	{ // 288.75K 8 inch single density - gaps unverified
+		floppy_image::FF_8, floppy_image::SSSD, floppy_image::FM,
+		2000, 15, 77, 1, 256, {}, 1, {}, 40, 12, 12
+	},
+	{ // 577.5K 8 inch single density - gaps unverified
+		floppy_image::FF_8, floppy_image::DSSD, floppy_image::FM,
+		2000, 15, 77, 2, 256, {}, 1, {}, 40, 12, 12
+	},
+	{ // 500.5K 8 inch double density - gaps unverified
+		floppy_image::FF_8, floppy_image::SSDD, floppy_image::MFM,
+		1000, 26, 77, 1, 256, {}, 1, {}, 80, 22, 24
+	},
+	{ // 1001K 8 inch double density - gaps unverified
+		floppy_image::FF_8, floppy_image::DSDD, floppy_image::MFM,
+		1000, 26, 77, 2, 256, {}, 1, {}, 80, 22, 24
+	},
+	{   /* 1440K 3 1/2 inch high density */
+		floppy_image::FF_35,  floppy_image::DSHD, floppy_image::MFM,
+		1000, 36, 80, 2, 256, {}, 1, {}, 80, 22, 24
+	},
+	{}
+};
 
 const floppy_format_type FLOPPY_FLEX_FORMAT = &floppy_image_format_creator<flex_format>;

src/lib/formats/flex_dsk.h

@@ -11,8 +11,9 @@
 #pragma once
 
 #include "flopimg.h"
+#include "wd177x_dsk.h"
 
-class flex_format : public floppy_image_format_t
+class flex_format : public wd177x_format
 {
 public:
 	flex_format();
@@ -21,8 +22,9 @@ public:
 	virtual const char *description() const override;
 	virtual const char *extensions() const override;
 	virtual int identify(io_generic *io, uint32_t form_factor) override;
-	virtual bool load(io_generic *io, uint32_t form_factor, floppy_image *image) override;
+	virtual int find_size(io_generic *io, uint32_t form_factor) override;
-	virtual bool supports_save() const override;
+	virtual void build_sector_description(const format &f, uint8_t *sectdata, desc_s *sectors, int track, int head) const override;
+	virtual void check_compatibility(floppy_image *image, std::vector<int> &candidates) override;
 
 private:
 	struct sysinfo_sector
@@ -43,6 +45,10 @@ private:
 		uint8_t last_sec;
 		uint8_t unused2[216];
 	} info;
+	static const format formats[];
+
+	uint8_t boot0_sector_id;
+	uint8_t boot1_sector_id;
 };
 
 extern const floppy_format_type FLOPPY_FLEX_FORMAT;

src/lib/formats/wd177x_dsk.h

@@ -57,7 +57,7 @@ protected:
 
 	int compute_track_size(const format &f) const;
 	virtual void build_sector_description(const format &d, uint8_t *sectdata, desc_s *sectors, int track, int head) const;
-	void check_compatibility(floppy_image *image, std::vector<int> &candidates);
+	virtual void check_compatibility(floppy_image *image, std::vector<int> &candidates);
 	void extract_sectors(floppy_image *image, const format &f, desc_s *sdesc, int track, int head);
 };