// license:BSD-3-Clause // copyright-holders: Ansgar Kückes, F. Ulivi /********************************************************************* hpi_dsk.cpp HP9885/HP9895A "HPI" disk images CHS = 67/1/30 (SSDD) CHS = 77/2/30 (DSDD) Sector size 256 bytes Cell size 2 µs Gap1 = 16 x 0x00 Gap2 = 34 x 0x00 Gap3 = ~490 x 0x00 (depends on actual rotation speed) Sync = 4 x 0x00 + 4 x 0xff ID AM = 0x0e clock + 0x70 data Data AM = 0x0e clock + 0x50 data DefectTrack AM = 0x0e clock + 0xf0 data CRC-16 excludes address markers MMFM/M2FM encoding (LS bit first) The order of sectors in a track depends on the interleave factor which is the distance (in number of sectors) between two consecutively numbered sectors. Interleave factor is specified at formatting time. The default factor is 7. The order of sectors for this factor is: 0, 13, 26, 9, 22, 5, 18, 1, 14, 27, 10, 23, 6, 19, 2, 15, 28, 11, 24, 7, 20, 3, 16, 29, 12, 25, 8, 21, 4, 17 := [Index hole]|Sector0|Gap2|Sector1|Gap2|...|Sector29|Gap3| := ID field|Gap1|Data field := Sync|ID AM|Track no.|Sector no.|CRC-16|0x00 := Sync|Data AM|Data|CRC-16|0x00 This format is just a raw image of every sector on a HP-formatted 8" floppy disk. Files with this format have no header/trailer and are exactly 1182720 bytes in size (30 sectors, 2 heads, 77 tracks, 256 bytes per sector). There's also a "reduced" version holding just 75 cylinders. When loading, the disk image is translated to MMFM encoding so that it can be loaded into HP9885/HP9895 emulator. *********************************************************************/ #include "hpi_dsk.h" #include "coretmpl.h" // BIT #include "ioprocs.h" #include "osdcore.h" // osd_printf_* // Debugging #define VERBOSE 0 #define LOG(...) do { if (VERBOSE) osd_printf_info(__VA_ARGS__); } while (false) constexpr unsigned IL_OFFSET = 0x12; // Position of interleave factor in HPI image (2 bytes, big-endian) constexpr unsigned DEFAULT_IL = 7; // Default interleaving factor constexpr unsigned CELL_SIZE = 1200; // Bit cell size (1 µs) constexpr uint8_t ID_AM = 0x70; // ID address mark constexpr uint8_t DATA_AM = 0x50; // Data address mark constexpr uint8_t AM_CLOCK = 0x0e; // Clock pattern of AM constexpr uint32_t ID_CD_PATTERN= 0x55552a54; // C/D pattern of 0xff + ID_AM constexpr uint32_t DATA_CD_PATTERN = 0x55552a44; // C/D pattern of 0xff + DATA_AM constexpr unsigned GAP1_SIZE = 17; // Size of gap 1 (+1) constexpr unsigned GAP2_SIZE = 35; // Size of gap 2 (+1) constexpr int ID_DATA_OFFSET = 30 * 16; // Nominal distance (in cells) between ID & DATA AM constexpr unsigned HPI_RED_TRACKS = 75; // Reduced number of tracks hpi_format::hpi_format() { } int hpi_format::identify(util::random_read &io, uint32_t form_factor, const std::vector &variants) const { uint64_t size; if (io.length(size)) { return 0; } // we try to stay back and give only 50 points, since another image // format may also have images of the same size (there is no header and no // magic number for HPI format... unsigned dummy_heads; unsigned dummy_tracks; if (((form_factor == floppy_image::FF_8) || (form_factor == floppy_image::FF_UNKNOWN)) && geometry_from_size(size , dummy_heads , dummy_tracks)) { return FIFID_SIZE; } else { return 0; } } bool hpi_format::geometry_from_size(uint64_t image_size , unsigned& heads , unsigned& tracks) { if ((image_size % HPI_SECTOR_SIZE) != 0) { // Not a whole number of sectors return false; } unsigned sectors = unsigned(image_size / HPI_SECTOR_SIZE); if ((sectors % HPI_SECTORS) != 0) { // Not a whole number of tracks return false; } unsigned tot_tracks = sectors / HPI_SECTORS; // Possible combinations // // | Tot tracks | Heads | Tracks | Format | // |------------+-------+--------+--------| // | 67 | 1 | 67 | SSDD | // | 77 | 1 | 77 | SSDD | // | 150 | 2 | 75 | DSDD | // | 154 | 2 | 77 | DSDD | // switch (tot_tracks) { case HPI_9885_TRACKS: heads = 1; tracks = HPI_9885_TRACKS; return true; case HPI_TRACKS: heads = 1; tracks = HPI_TRACKS; return true; case HPI_RED_TRACKS * 2: heads = 2; tracks = HPI_RED_TRACKS; return true; case HPI_TRACKS * 2: heads = 2; tracks = HPI_TRACKS; return true; default: return false; } } bool hpi_format::load(util::random_read &io, uint32_t form_factor, const std::vector &variants, floppy_image &image) const { unsigned heads; unsigned cylinders; uint64_t size; if (io.length(size)) { return false; } if (!geometry_from_size(size, heads, cylinders)) { return false; } int max_tracks; int max_heads; image.get_maximal_geometry(max_tracks , max_heads); if (cylinders > max_tracks || heads > max_heads) { return false; } image.set_variant(heads == 2 ? floppy_image::DSDD : floppy_image::SSDD); // Suck in the whole image auto const [err, image_data, actual] = read_at(io, 0, size); if (err || (actual != size)) { return false; } // Get interleave factor from image unsigned il = (unsigned)image_data[ IL_OFFSET ] * 256 + image_data[ IL_OFFSET + 1 ]; LOG("I/L from image: %u\n" , il); if (il < 1 || il >= HPI_SECTORS) { il = DEFAULT_IL; } LOG("Actual I/L: %u\n" , il); sector_list_t sector_list; interleaved_sectors(il, sector_list); unsigned list_offset = 0; for (unsigned cyl = 0; cyl < cylinders; cyl++) { for (unsigned head = 0; head < heads; head++) { std::vector track_data; for (unsigned sector = 0; sector < HPI_SECTORS; sector++) { unsigned real_sector = sector_list[ (sector + list_offset) % HPI_SECTORS ]; unsigned offset_in_image = chs_to_lba(cyl, head, real_sector, heads) * HPI_SECTOR_SIZE; write_sector(track_data , cyl , real_sector + (head << 7) , &image_data[ offset_in_image ]); } fill_with_gap3(track_data); generate_track_from_levels(cyl , head , track_data , 0 , image); list_offset = (list_offset + m_track_skew[ il - 1 ][ head ]) % HPI_SECTORS; } } return true; } bool hpi_format::save(util::random_read_write &io, const std::vector &variants, const floppy_image &image) const { int tracks; int heads; image.get_actual_geometry(tracks, heads); for (int cyl = 0; cyl < tracks; cyl++) { for (int head = 0; head < heads; head++) { auto bitstream = generate_bitstream_from_track(cyl , head , CELL_SIZE , image , 0); int pos = 0; unsigned track_no , head_no , sector_no; uint8_t sector_data[ HPI_SECTOR_SIZE ]; while (get_next_sector(bitstream , pos , track_no , head_no , sector_no , sector_data)) { if (track_no == cyl && head_no == head && sector_no < HPI_SECTORS) { unsigned offset_in_image = chs_to_lba(cyl, head, sector_no, heads) * HPI_SECTOR_SIZE; /*auto const [err, actual] =*/ write_at(io, offset_in_image, sector_data, HPI_SECTOR_SIZE); // FIXME: check for errors } } } } return true; } const char *hpi_format::name() const noexcept { return "hpi"; } const char *hpi_format::description() const noexcept { return "HP9895A floppy disk image"; } const char *hpi_format::extensions() const noexcept { return "hpi"; } bool hpi_format::supports_save() const noexcept { return true; } void hpi_format::interleaved_sectors(unsigned il_factor , sector_list_t& sector_list) { sector_list.fill(0xff); unsigned idx = HPI_SECTORS - il_factor; for (unsigned sect = 0; sect < HPI_SECTORS; sect++) { idx = (idx + il_factor) % HPI_SECTORS; while (sector_list[ idx ] != 0xff) { idx = (idx + 1) % HPI_SECTORS; } LOG("[%u]=%u\n" , idx , sect); sector_list[ idx ] = sect; } } void hpi_format::write_mmfm_bit(std::vector &buffer , bool data_bit , bool clock_bit) { bool had_transition = buffer.size() < 2 ? false : bit_r(buffer, buffer.size() - 1) || bit_r(buffer , buffer.size() - 2); clock_bit = !data_bit && (clock_bit || !had_transition); bit_w(buffer , clock_bit , CELL_SIZE); bit_w(buffer , data_bit , CELL_SIZE); } void hpi_format::write_mmfm_byte(std::vector &buffer , uint8_t data , uint8_t clock) { for (unsigned i = 0; i < 8; i++) { write_mmfm_bit(buffer , util::BIT(data , i) , util::BIT(clock , i)); } } void hpi_format::write_sync(std::vector &buffer) { // Sync // 4x 00 for (unsigned i = 0; i < 4; i++) { write_mmfm_byte(buffer , 0); } // 4x ff for (unsigned i = 0; i < 4; i++) { write_mmfm_byte(buffer , 0xff); } } void hpi_format::write_crc(std::vector &buffer , uint16_t crc) { // Note that CRC is stored with MSB (x^15) first for (unsigned i = 0; i < 16; i++) { write_mmfm_bit(buffer , util::BIT(crc , 15 - i) , 0); } } void hpi_format::write_sector(std::vector &buffer , uint8_t track_no , uint8_t sect_head_no , const uint8_t *sect_data) { // **** On-disk format of a sector **** // // | Offset | Size | Value | Content | // |--------+------+-------+----------------------| // | 0 | 4 | 00 | Sync | // | 4 | 4 | ff | Sync | // | 8 | 1 | 70 | ID AM (clock = 0e) | // | 9 | 1 | xx | Track no. | // | 10 | 1 | xx | Sector and head no. | // | 11 | 2 | xx | ID CRC | // | 13 | 1 | 00 | ID tail | // | 14 | 16 | 00 | Gap 1 | // | 30 | 4 | 00 | Sync | // | 34 | 4 | ff | Sync | // | 38 | 1 | 50 | Data AM (clock = 0e) | // | 39 | 256 | xx | Sector data | // | 295 | 2 | xx | Data CRC | // | 297 | 1 | 00 | Data tail | // | 298 | 34 | 00 | Gap 2 | // | 332 | | | | // Sync write_sync(buffer); // ID AM write_mmfm_byte(buffer , ID_AM , AM_CLOCK); auto crc_start = buffer.size(); // Track # write_mmfm_byte(buffer , track_no); // Sector/head # write_mmfm_byte(buffer , sect_head_no); uint16_t crc = calc_crc_ccitt(buffer , crc_start , buffer.size()); // ID CRC write_crc(buffer , crc); // Gap 1 for (unsigned i = 0; i < GAP1_SIZE; i++) { write_mmfm_byte(buffer , 0); } // Sync write_sync(buffer); // Data AM write_mmfm_byte(buffer , DATA_AM , AM_CLOCK); crc_start = buffer.size(); for (unsigned i = 0; i < HPI_SECTOR_SIZE; i += 2) { // Data: bytes are swapped in pairs write_mmfm_byte(buffer , sect_data[ i + 1 ]); write_mmfm_byte(buffer , sect_data[ i ]); } crc = calc_crc_ccitt(buffer , crc_start , buffer.size()); // Data CRC write_crc(buffer , crc); // Gap 2 for (unsigned i = 0; i < GAP2_SIZE; i++) { write_mmfm_byte(buffer , 0); } } void hpi_format::fill_with_gap3(std::vector &buffer) { // Cell count in a track (1 µs cells in a 1/6 s track) unsigned cell_count = (500000 * 120) / 360; unsigned cells_in_buffer = buffer.size(); // Size of gap 3 unsigned gap_3 = (cell_count - cells_in_buffer) / 16; // Gap 3 for (unsigned i = 0; i < gap_3; i++) { write_mmfm_byte(buffer , 0); } // Last cell to round everything up to 2E+8 if (buffer.size() * CELL_SIZE < 200000000) { bit_w(buffer , false , 200000000 - buffer.size() * CELL_SIZE); } } unsigned hpi_format::chs_to_lba(unsigned cylinder , unsigned head , unsigned sector , unsigned heads) { return sector + (head + cylinder * heads) * HPI_SECTORS; } std::vector hpi_format::get_next_id_n_block(const std::vector &bitstream , int& pos , int& start_pos) { std::vector res; uint32_t sr = 0; // Look for either sync + ID AM or sync + DATA AM while (pos < bitstream.size() && sr != ID_CD_PATTERN && sr != DATA_CD_PATTERN) { sr = (sr << 1) | bitstream[pos]; pos++; } if (pos == bitstream.size()) { // End of track reached return res; } start_pos = pos; // ID blocks: Track no. + sector/head no. + CRC // Data blocks: Sector data + CRC unsigned to_dump; if (sr == ID_CD_PATTERN) { to_dump = 4; res.push_back(ID_AM); } else { to_dump = HPI_SECTOR_SIZE + 2; res.push_back(DATA_AM); } // Align to data cells pos++; for (unsigned i = 0; i < to_dump && pos < bitstream.size(); i++) { uint8_t byte = 0; unsigned j; for (j = 0; j < 8 && pos < bitstream.size(); j++) { bool bit = bitstream[pos]; pos += 2; byte >>= 1; if (bit) { byte |= 0x80; } } if (j == 8) { res.push_back(byte); } } return res; } bool hpi_format::get_next_sector(const std::vector &bitstream , int& pos , unsigned& track , unsigned& head , unsigned& sector , uint8_t *sector_data) { std::vector block; while (true) { // Scan for ID block first int id_pos = 0; while (true) { if (block.size() == 0) { block = get_next_id_n_block(bitstream , pos , id_pos); if (block.size() == 0) { return false; } } if (block[ 0 ] == ID_AM && block.size() >= 3) { track = block[ 1 ]; head = block[ 2 ] >> 7; sector = block[ 2 ] & 0x7f; break; } else { block.clear(); } } // Then for DATA block int data_pos = 0; block = get_next_id_n_block(bitstream , pos , data_pos); if (block.size() == 0) { return false; } if (block[ 0 ] == DATA_AM && block.size() >= (HPI_SECTOR_SIZE + 1) && abs((data_pos - id_pos) - ID_DATA_OFFSET) <= 16) { break; } } for (unsigned i = 0; i < HPI_SECTOR_SIZE; i += 2) { sector_data[ i ] = block[ i + 2 ]; sector_data[ i + 1 ] = block[ i + 1 ]; } return true; } // This table comes straight from hp9895 firmware (it's @ 0x0f90) // For each interleave factor in [1..29] it stores the number of positions // to move forward in the interleaved sector list when beginning a new track. // There are different offsets for tracks on head 0 and tracks on head 1. const uint8_t hpi_format::m_track_skew[ HPI_SECTORS - 1 ][ HPI_HEADS ] = { { 0x1c , 0x18 }, // Interleave = 1 { 0x1c , 0x18 }, // Interleave = 2 { 0x1c , 0x18 }, // Interleave = 3 { 0x1d , 0x1a }, // Interleave = 4 { 0x1a , 0x18 }, // Interleave = 5 { 0x19 , 0x18 }, // Interleave = 6 { 0x00 , 0x00 }, // Interleave = 7 { 0x1d , 0x1d }, // Interleave = 8 { 0x1c , 0x1c }, // Interleave = 9 { 0x15 , 0x15 }, // Interleave = 10 { 0x00 , 0x00 }, // Interleave = 11 { 0x19 , 0x19 }, // Interleave = 12 { 0x00 , 0x00 }, // Interleave = 13 { 0x1d , 0x1d }, // Interleave = 14 { 0x10 , 0x10 }, // Interleave = 15 { 0x1d , 0x1d }, // Interleave = 16 { 0x00 , 0x00 }, // Interleave = 17 { 0x19 , 0x19 }, // Interleave = 18 { 0x00 , 0x00 }, // Interleave = 19 { 0x15 , 0x15 }, // Interleave = 20 { 0x1c , 0x1c }, // Interleave = 21 { 0x1d , 0x1d }, // Interleave = 22 { 0x00 , 0x00 }, // Interleave = 23 { 0x19 , 0x19 }, // Interleave = 24 { 0x1a , 0x1a }, // Interleave = 25 { 0x1d , 0x1d }, // Interleave = 26 { 0x1c , 0x1c }, // Interleave = 27 { 0x1d , 0x1d }, // Interleave = 28 { 0x00 , 0x00 } // Interleave = 29 }; const hpi_format FLOPPY_HPI_FORMAT;