diff options
Diffstat (limited to 'src/lib/formats/nfd_dsk.cpp')
-rw-r--r-- | src/lib/formats/nfd_dsk.cpp | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/src/lib/formats/nfd_dsk.cpp b/src/lib/formats/nfd_dsk.cpp new file mode 100644 index 00000000000..816498190a7 --- /dev/null +++ b/src/lib/formats/nfd_dsk.cpp @@ -0,0 +1,282 @@ +// 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>; |