// license:BSD-3-Clause // copyright-holders:Olivier Galibert /********************************************************************* formats/m20_dsk.cpp Olivetti M20 floppy-disk images Track 0/head 0 is FM, 128 byte sectors. The rest is MFM, 256 byte sectors. In image files the sectors of track 0/sector 0 are 256 bytes long to simplify access. Only the first half of these sectors contain image data. *********************************************************************/ #include "m20_dsk.h" #include "ioprocs.h" m20_format::m20_format() { } const char *m20_format::name() const noexcept { return "m20"; } const char *m20_format::description() const noexcept { return "M20 disk image"; } const char *m20_format::extensions() const noexcept { return "img"; } bool m20_format::supports_save() const noexcept { return true; } int m20_format::identify(util::random_read &io, uint32_t form_factor, const std::vector &variants) const { uint64_t size; if (io.length(size)) return 0; if (size == 286720) return FIFID_SIZE; return 0; } bool m20_format::load(util::random_read &io, uint32_t form_factor, const std::vector &variants, floppy_image &image) const { for (int track = 0; track < 35; track++) for (int head = 0; head < 2; head ++) { bool mfm = track || head; desc_pc_sector sects[16]; uint8_t sectdata[16*256]; /*auto const [err, actual] =*/ read_at(io, 16*256*(track*2+head), sectdata, 16*256); // FIXME: check for errors and premature EOF for (int i = 0; i < 16; i++) { int j = i/2 + (i & 1 ? 0 : 8); sects[i].track = track; sects[i].head = head; sects[i].sector = j+1; sects[i].size = mfm ? 1 : 0; sects[i].actual_size = mfm ? 256 : 128; sects[i].data = sectdata + 256*j; sects[i].deleted = false; sects[i].bad_crc = false; } if(mfm) build_wd_track_mfm(track, head, image, 100000, 16, sects, 50, 32, 22); else build_wd_track_fm(track, head, image, 50000, 16, sects, 24, 16, 11); } return true; } bool m20_format::save(util::random_read_write &io, const std::vector &variants, const floppy_image &image) const { uint64_t file_offset = 0; int track_count, head_count; track_count = 35; head_count = 2; //FIXME: use image.get_actual_geometry(track_count, head_count) instead // initial FM track auto bitstream = generate_bitstream_from_track(0, 0, 4000, image); auto sectors = extract_sectors_from_bitstream_fm_pc(bitstream); for (int i = 0; i < 16; i++) { /*auto const [err, actual] =*/ write_at(io, file_offset, sectors[i + 1].data(), 128); // FIXME: check for errors file_offset += 256; //128; } // rest are MFM tracks for (int track = 0; track < track_count; track++) { for (int head = 0; head < head_count; head++) { // skip track 0, head 0 if (track == 0) { if (head_count == 1) break; else head++; } bitstream = generate_bitstream_from_track(track, head, 2000, image); sectors = extract_sectors_from_bitstream_mfm_pc(bitstream); for (int i = 0; i < 16; i++) { /*auto const [err, actual] =*/ write_at(io, file_offset, sectors[i + 1].data(), 256); // FIXME: check for errors file_offset += 256; } } } return true; } const m20_format FLOPPY_M20_FORMAT;