// license:BSD-3-Clause // copyright-holders:Olivier Galibert /********************************************************************* formats/m20_dsk.c 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" m20_format::m20_format() { } const char *m20_format::name() const { return "m20"; } const char *m20_format::description() const { return "M20 disk image"; } const char *m20_format::extensions() const { return "img"; } bool m20_format::supports_save() const { return true; } int m20_format::identify(io_generic *io, uint32_t form_factor) { if(io_generic_size(io) == 286720) return 50; return 0; } bool m20_format::load(io_generic *io, uint32_t form_factor, floppy_image *image) { 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]; io_generic_read(io, sectdata, 16*256*(track*2+head), 16*256); 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(io_generic *io, floppy_image *image) { uint8_t bitstream[500000/8]; uint8_t sector_data[50000]; desc_xs sectors[256]; int track_size; 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 generate_bitstream_from_track(0, 0, 4000, bitstream, track_size, image); extract_sectors_from_bitstream_fm_pc(bitstream, track_size, sectors, sector_data, sizeof(sector_data)); for (int i = 0; i < 16; i++) { io_generic_write(io, sectors[i + 1].data, file_offset, 128); 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++; } generate_bitstream_from_track(track, head, 2000, bitstream, track_size, image); extract_sectors_from_bitstream_mfm_pc(bitstream, track_size, sectors, sector_data, sizeof(sector_data)); for (int i = 0; i < 16; i++) { io_generic_write(io, sectors[i + 1].data, file_offset, 256); file_offset += 256; } } } return true; } const floppy_format_type FLOPPY_M20_FORMAT = &floppy_image_format_creator;