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-rw-r--r--src/lib/formats/nfd_dsk.cpp282
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diff --git a/src/lib/formats/nfd_dsk.cpp b/src/lib/formats/nfd_dsk.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Fabio Priuli
+/*********************************************************************
+
+ formats/nfd_dsk.h
+
+ PC98 NFD disk images (info from: http://www.geocities.jp/t98next/dev.html )
+
+ Revision 0
+ ==========
+
+ header structure (variable length > 0x120, header length = DWORD at 0x110)
+ 0x000-0x00F = T98FDDIMAGE.R* followed by 2 0x00 bytes, * = format revision (0 or 1 so far)
+ 0x010-0x10F = space for image info / comments
+ 0x110-0x113 = header length (DWORD)
+ 0x114 = write protect (any value > 0 means not writeable)
+ 0x115 = number of heads
+ 0x116-0x11F = reserved
+ 0x120-EOHeader = sector map (0x10 for each sector of the disk!)
+ last 0x10 are fixed to 0x00, probably it marks the end of sector map?
+
+ sector map structure
+ 0x0 = track number
+ 0x1 = head
+ 0x2 = sector number
+ 0x3 = sector size (in 128byte chunks)
+ 0x4 = MFM/FM (1 = MFM, 0 = FM)?
+ 0x5 = DDAM/DAM (1 = DDAM, 0 = DAM)
+ 0x6-0x9 = READ DATA (FDDBIOS) Results (Status, St0, St1, St2) ??
+ 0xA = PDA (disk type)
+ 0xB-0xF = reserved and equal to 0x00 (possibly available for future format extensions?)
+
+
+ Revision 1
+ ==========
+
+ header structure (variable length > 0x120, header length = DWORD at 0x110)
+ 0x000-0x11F = same as Rev. 0 format
+ 0x120-0x3AF = 164 DWORDs containing, for each track, the absolute position of the sector maps
+ for sectors of the track. for unformatted/unused tracks 0 is used
+ 0x3B0-0x3B3 = absolute position of addintional info in the header, if any
+ 0x3B4-0x3BF = reserved
+ 0x120-EOHeader = sector map + special data for each track:
+ first 0x10 of each track = #sectors (WORD), #extra data (WORD), reserved 0xc bytes zeroed
+ then 0x10 for each sector of this track and 0x10 for each extra data chunk
+
+ sector map structure
+ 0x0 = track number
+ 0x1 = head
+ 0x2 = sector number
+ 0x3 = sector size (in 128byte chunks)
+ 0x4 = MFM/FM (1 = MFM, 0 = FM)?
+ 0x5 = DDAM/DAM (1 = DDAM, 0 = DAM)
+ 0x6-0x9 = READ DATA (FDDBIOS) Results (Status, St0, St1, St2) ??
+ 0xA = RETRY DATA (1 = Yes, 0 = No)
+ 0xB = PDA (disk type)
+ 0xC-0xF = reserved and equal to 0x00 (possibly available for future format extensions?)
+
+ extra data map structure
+ 0x0 = command
+ 0x1 = track number
+ 0x2 = head
+ 0x3 = sector number
+ 0x4 = sector size (in 128byte chunks)
+ 0x5-0x8 = READ DATA (FDDBIOS) Results (Status, St0, St1, St2) ??
+ 0x9 = Number of times to RETRY loading data
+ 0xA-0xD = length of RETRY DATA
+ 0xE = PDA (disk type)
+ 0xF = reserved and equal to 0x00 (possibly available for future format extensions?)
+
+ TODO:
+ - add support for write protect header bit? apparently, some disks try to write and
+ fail to boot if they succeed which is the reason this bit was added
+ - add support for DDAM in Rev. 0 (need an image which set it in some sector)
+ - investigate the READ DATA bytes of sector headers
+ - investigate RETRY DATA chunks
+
+ *********************************************************************/
+
+ #include <assert.h>
+
+#include "nfd_dsk.h"
+
+nfd_format::nfd_format()
+{
+}
+
+const char *nfd_format::name() const
+{
+ return "nfd";
+}
+
+const char *nfd_format::description() const
+{
+ return "NFD disk image";
+}
+
+const char *nfd_format::extensions() const
+{
+ return "nfd";
+}
+
+int nfd_format::identify(io_generic *io, UINT32 form_factor)
+{
+ UINT8 h[16];
+ io_generic_read(io, h, 0, 16);
+
+ if (strncmp((const char *)h, "T98FDDIMAGE.R0", 14) == 0 || strncmp((const char *)h, "T98FDDIMAGE.R1", 14) == 0)
+ return 100;
+
+ return 0;
+}
+
+bool nfd_format::load(io_generic *io, UINT32 form_factor, floppy_image *image)
+{
+ UINT64 size = io_generic_size(io);
+ UINT8 h[0x120], hsec[0x10];
+ io_generic_read(io, h, 0, 0x120);
+ int format_version = !strncmp((const char *)h, "T98FDDIMAGE.R0", 14) ? 0 : 1;
+
+ // sector map (the 164th entry is only used by rev.1 format, loops with track < 163 are correct for rev.0)
+ UINT8 disk_type = 0;
+ UINT8 num_secs[164];
+ UINT8 num_specials[164];
+ UINT32 track_sizes[164];
+ UINT8 tracks[164 * 26];
+ UINT8 heads[164 * 26];
+ UINT8 secs[164 * 26];
+ UINT8 mfm[164 * 26];
+ UINT8 sec_sizes[164 * 26];
+
+ UINT32 hsize = LITTLE_ENDIANIZE_INT32(*(UINT32 *)(h+0x110));
+
+ int pos = 0x120;
+
+ // set up sector map
+ if (format_version == 1)
+ {
+ for (int track = 0; track < 164; track++)
+ {
+ int curr_track_size = 0;
+ // read sector map absolute location
+ io_generic_read(io, hsec, pos, 4);
+ pos += 4;
+ UINT32 secmap_addr = LITTLE_ENDIANIZE_INT32(*(UINT32 *)(hsec));
+
+ if (secmap_addr)
+ {
+ // read actual sector map for the sectors of this track
+ // for rev.1 format the first 0x10 are a track summary:
+ // first WORD is # of sectors, second WORD is # of special data sectors
+ io_generic_read(io, hsec, secmap_addr, 0x10);
+ secmap_addr += 0x10;
+ num_secs[track] = LITTLE_ENDIANIZE_INT16(*(UINT16 *)(hsec));
+ num_specials[track] = LITTLE_ENDIANIZE_INT16(*(UINT16 *)(hsec + 0x2));
+
+ for (int sect = 0; sect < num_secs[track]; sect++)
+ {
+ io_generic_read(io, hsec, secmap_addr, 0x10);
+
+ if (track == 0 && sect == 0)
+ disk_type = hsec[0xb]; // can this change across the disk? I don't think so...
+ secmap_addr += 0x10;
+
+ tracks[(track * 26) + sect] = hsec[0];
+ heads[(track * 26) + sect] = hsec[1];
+ secs[(track * 26) + sect] = hsec[2];
+ sec_sizes[(track * 26) + sect] = hsec[3];
+ mfm[(track * 26) + sect] = hsec[4];
+
+ curr_track_size += (128 << hsec[3]);
+ }
+
+ if (num_specials[track] > 0)
+ {
+ for (int sect = 0; sect < num_specials[track]; sect++)
+ {
+ io_generic_read(io, hsec, secmap_addr, 0x10);
+ secmap_addr += 0x10;
+ curr_track_size += (hsec[9] + 1) * LITTLE_ENDIANIZE_INT32(*(UINT32 *)(hsec + 0x0a));
+ }
+ }
+ }
+ else
+ {
+ num_secs[track] = 0;
+ num_specials[track] = 0;
+ }
+ track_sizes[track] = curr_track_size;
+ }
+ }
+ else
+ {
+ for (int track = 0; track < 163 && pos < hsize; track++)
+ {
+ int curr_num_sec = 0, curr_track_size = 0;
+ for (int sect = 0; sect < 26; sect++)
+ {
+ // read sector map for this sector
+ // for rev.0 format each sector uses 0x10 bytes
+ io_generic_read(io, hsec, pos, 0x10);
+
+ if (track == 0 && sect == 0)
+ disk_type = hsec[0xa]; // can this change across the disk? I don't think so...
+ pos += 0x10;
+
+ if (hsec[0] == 0xff) // unformatted/unused sector
+ continue;
+
+ tracks[(track * 26) + sect] = hsec[0];
+ heads[(track * 26) + sect] = hsec[1];
+ secs[(track * 26) + sect] = hsec[2];
+ sec_sizes[(track * 26) + sect] = hsec[3];
+ mfm[(track * 26) + sect] = hsec[4];
+
+ curr_track_size += (128 << hsec[3]);
+ curr_num_sec++;
+ }
+
+ num_secs[track] = curr_num_sec;
+ track_sizes[track] = curr_track_size;
+ }
+ }
+
+ // shouln't this be set-up depending on disk_type? gaplus does not like having less than 166666 cells
+ int cell_count = form_factor == floppy_image::FF_35 ? 200000 : 166666;
+
+ switch (disk_type)
+ {
+ case 0x10: // 640K disk, 2DD
+ image->set_variant(floppy_image::DSDD);
+ break;
+ //case 0x30: // 1.44M disk, ?? (no images found)
+ // break;
+ case 0x90: // 1.2M disk, 2HD
+ default:
+ image->set_variant(floppy_image::DSHD);
+ break;
+ }
+
+ desc_pc_sector sects[256];
+ UINT8 sect_data[65536];
+ int cur_sec_map = 0, sector_size;
+ pos = hsize;
+
+ for (int track = 0; track < 163 && pos < size; track++)
+ {
+ io_generic_read(io, sect_data, pos, track_sizes[track]);
+
+ for (int i = 0; i < num_secs[track]; i++)
+ {
+ cur_sec_map = track * 26 + i;
+ sector_size = 128 << sec_sizes[cur_sec_map];
+ sects[i].track = tracks[cur_sec_map];
+ sects[i].head = heads[cur_sec_map];
+ sects[i].sector = secs[cur_sec_map];
+ sects[i].size = sec_sizes[cur_sec_map];
+ sects[i].actual_size = sector_size;
+ sects[i].deleted = false;
+ sects[i].bad_crc = false;
+ sects[i].data = sect_data + i * sector_size;
+ }
+ pos += track_sizes[track];
+
+ // notice that the operation below might fail if sectors of the same track have variable sec_sizes,
+ // because the gap3 calculation would account correctly only for the first sector...
+ // examined images had constant sec_sizes in the each track, so probably this is not an issue
+ if (mfm[track * 26])
+ build_pc_track_mfm(track / 2, track % 2, image, cell_count, num_secs[track], sects, calc_default_pc_gap3_size(form_factor, (128 << sec_sizes[track * 26])));
+ else
+ build_pc_track_fm(track / 2, track % 2, image, cell_count, num_secs[track], sects, calc_default_pc_gap3_size(form_factor, (128 << sec_sizes[track * 26])));
+ }
+
+ return true;
+}
+
+bool nfd_format::supports_save() const
+{
+ return false;
+}
+
+const floppy_format_type FLOPPY_NFD_FORMAT = &floppy_image_format_creator<nfd_format>;