diff options
Diffstat (limited to 'src/lib/formats/g64_dsk.cpp')
-rw-r--r-- | src/lib/formats/g64_dsk.cpp | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/src/lib/formats/g64_dsk.cpp b/src/lib/formats/g64_dsk.cpp new file mode 100644 index 00000000000..6cbb345adc8 --- /dev/null +++ b/src/lib/formats/g64_dsk.cpp @@ -0,0 +1,179 @@ +// license:BSD-3-Clause +// copyright-holders:Curt Coder +/********************************************************************* + + formats/g64_dsk.c + + Commodore 1541/1571 GCR disk image format + + http://unusedino.de/ec64/technical/formats/g64.html + +*********************************************************************/ + +#include "emu.h" // emu_fatalerror +#include "formats/g64_dsk.h" + +#define G64_FORMAT_HEADER "GCR-1541" + +g64_format::g64_format() +{ +} + +const UINT32 g64_format::c1541_cell_size[] = +{ + 4000, // 16MHz/16/4 + 3750, // 16MHz/15/4 + 3500, // 16MHz/14/4 + 3250 // 16MHz/13/4 +}; + +int g64_format::identify(io_generic *io, UINT32 form_factor) +{ + char h[8]; + + io_generic_read(io, h, 0, 8); + if (!memcmp(h, G64_FORMAT_HEADER, 8)) { + return 100; + } + return 0; +} + +bool g64_format::load(io_generic *io, UINT32 form_factor, floppy_image *image) +{ + UINT64 size = io_generic_size(io); + dynamic_buffer img(size); + io_generic_read(io, &img[0], 0, size); + + if (img[POS_VERSION]) { + throw emu_fatalerror("g64_format: Unsupported version %u", img[POS_VERSION]); + } + + int track_count = img[POS_TRACK_COUNT]; + int head = 0; + + for (int track = 0; track < track_count; track++) + { + int cylinder = track % TRACK_COUNT; + + if (track == TRACK_COUNT) + head = 1; + + UINT32 tpos = POS_TRACK_OFFSET + (track * 4); + UINT32 spos = tpos + (track_count * 4); + UINT32 dpos = pick_integer_le(&img[0], tpos, 4); + + if (!dpos) + continue; + + if (dpos > size) + throw emu_fatalerror("g64_format: Track %u offset %06x out of bounds", track, dpos); + + UINT32 speed_zone = pick_integer_le(&img[0], spos, 4); + + if (speed_zone > 3) + throw emu_fatalerror("g64_format: Unsupported variable speed zones on track %d", track); + + UINT16 track_bytes = pick_integer_le(&img[0], dpos, 2); + int track_size = track_bytes * 8; + + LOG_FORMATS("head %u track %u offs %u size %u cell %ld\n", head, cylinder, dpos, track_bytes, 200000000L/track_size); + + generate_track_from_bitstream(cylinder, head, &img[dpos+2], track_size, image); + } + + if (!head) + image->set_variant(floppy_image::SSSD); + else + image->set_variant(floppy_image::DSSD); + + return true; +} + +int g64_format::generate_bitstream(int track, int head, int speed_zone, UINT8 *trackbuf, int &track_size, floppy_image *image) +{ + int cell_size = c1541_cell_size[speed_zone]; + + generate_bitstream_from_track(track, head, cell_size, trackbuf, track_size, image); + + int actual_cell_size = 200000000L/track_size; + + // allow a tolerance of +- 10 us (3990..4010 -> 4000) + return ((actual_cell_size >= cell_size-10) && (actual_cell_size <= cell_size+10)) ? speed_zone : -1; +} + +bool g64_format::save(io_generic *io, floppy_image *image) +{ + int tracks, heads; + image->get_actual_geometry(tracks, heads); + tracks = TRACK_COUNT * heads; + + // write header + UINT8 header[] = { 'G', 'C', 'R', '-', '1', '5', '4', '1', 0x00, tracks, TRACK_LENGTH & 0xff, TRACK_LENGTH >> 8 }; + io_generic_write(io, header, POS_SIGNATURE, sizeof(header)); + + // write tracks + for (int head = 0; head < heads; head++) { + int tracks_written = 0; + + dynamic_buffer trackbuf(TRACK_LENGTH-2); + + for (int track = 0; track < TRACK_COUNT; track++) { + UINT32 tpos = POS_TRACK_OFFSET + (track * 4); + UINT32 spos = tpos + (tracks * 4); + UINT32 dpos = POS_TRACK_OFFSET + (tracks * 4 * 2) + (tracks_written * TRACK_LENGTH); + + io_generic_write_filler(io, 0x00, tpos, 4); + io_generic_write_filler(io, 0x00, spos, 4); + + if (image->get_buffer(track, head).size() <= 1) + continue; + + int track_size; + int speed_zone; + + // figure out the cell size and speed zone from the track data + if ((speed_zone = generate_bitstream(track, head, 3, &trackbuf[0], track_size, image)) == -1) + if ((speed_zone = generate_bitstream(track, head, 2, &trackbuf[0], track_size, image)) == -1) + if ((speed_zone = generate_bitstream(track, head, 1, &trackbuf[0], track_size, image)) == -1) + if ((speed_zone = generate_bitstream(track, head, 0, &trackbuf[0], track_size, image)) == -1) + throw emu_fatalerror("g64_format: Cannot determine speed zone for track %u", track); + + LOG_FORMATS("head %u track %u size %u cell %u\n", head, track, track_size, c1541_cell_size[speed_zone]); + + UINT8 track_offset[4]; + UINT8 speed_offset[4]; + UINT8 track_length[2]; + + place_integer_le(track_offset, 0, 4, dpos); + place_integer_le(speed_offset, 0, 4, speed_zone); + place_integer_le(track_length, 0, 2, track_size/8); + + io_generic_write(io, track_offset, tpos, 4); + io_generic_write(io, speed_offset, spos, 4); + io_generic_write_filler(io, 0xff, dpos, TRACK_LENGTH); + io_generic_write(io, track_length, dpos, 2); + io_generic_write(io, &trackbuf[0], dpos + 2, track_size); + + tracks_written++; + } + } + + return true; +} + +const char *g64_format::name() const +{ + return "g64"; +} + +const char *g64_format::description() const +{ + return "Commodore 1541/1571 GCR disk image"; +} + +const char *g64_format::extensions() const +{ + return "g64,g41,g71"; +} + +const floppy_format_type FLOPPY_G64_FORMAT = &floppy_image_format_creator<g64_format>; |