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Diffstat (limited to 'src/lib/formats/lw30_dsk.cpp')
-rw-r--r-- | src/lib/formats/lw30_dsk.cpp | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/src/lib/formats/lw30_dsk.cpp b/src/lib/formats/lw30_dsk.cpp new file mode 100644 index 00000000000..dd1536755d5 --- /dev/null +++ b/src/lib/formats/lw30_dsk.cpp @@ -0,0 +1,213 @@ +// license:BSD-3-Clause +// copyright-holders:Bartman/Abyss +/*************************************************************************** + + Brother LW-30 Disk image format + see https://github.com/BartmanAbyss/brother-diskconv for disk conversion tool + +***************************************************************************/ +#include "lw30_dsk.h" + +#include "ioprocs.h" +#include "multibyte.h" + +#include <array> +#include <cassert> +#include <cstring> + + +namespace { + constexpr uint16_t sync_table[]{ + 0xdaef, 0xb7ad, 0xfbbe, 0xeadf, 0xbffa, 0xaeb6, 0xf5d7, 0xdbee, 0xbaab, 0xfdbd, + 0xebde, 0xd5f7, 0xafb5, 0xf6d6, 0xdded, 0xbbaa, 0xedbb, 0xd6dd, 0xb5f6, 0xf7af, + 0xded5, 0xbdeb, 0xabfd, 0xeeba, 0xd7db, 0xb6f5, 0xfaae, 0xdfbf, 0xbeea, 0xadfb, + 0xefb7, 0xdada, 0xb7ef, 0xfbad, 0xeabe, 0xbfdf, 0xaefa, 0xf5b6, 0xdbd7, 0xbaee, + 0xfdab, 0xebbd, 0xd5de, 0xaff7, 0xf6b5, 0xddd6, 0xbbed, 0xaadd, 0xedf6, 0xd6af, + 0xb5d5, 0xf7eb, 0xdefd, 0xbdba, 0xabdb, 0xeef5, 0xd7ae, 0xb6bf, 0xfaea, 0xdffb, + 0xbeb7, 0xadda, 0xefef, 0xdaad, 0xb7be, 0xfbdf, 0xeafa, 0xbfb6, 0xaed7, 0xf5ee, + 0xdbab, 0xbabd, 0xfdde, 0xebf7, 0xd5b5, 0xafd6, 0xf6ed, 0xddaa, 0xd6bb, 0xb5dd + }; + + constexpr uint8_t gcr_table[]{ + 0xaa, 0xab, 0xad, 0xae, 0xaf, 0xb5, 0xb6, 0xb7, + 0xba, 0xbb, 0xbd, 0xbe, 0xbf, 0xd5, 0xd6, 0xd7, + 0xda, 0xdb, 0xdd, 0xde, 0xdf, 0xea, 0xeb, 0xed, + 0xee, 0xef, 0xf5, 0xf6, 0xf7, 0xfa, 0xfb, 0xfd, + 0xfe, 0xff // FE, FF are reserved + }; + + // format + constexpr uint8_t sector_prefix[]{ + 0xbf, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xab + }; + + // write + constexpr uint8_t sector_header[]{ + 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, + 0xbf, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xed + }; + + // write + constexpr uint8_t sector_footer[]{ + 0xf5, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd + }; + + constexpr uint8_t sector_interleave1[]{ // 1-based + 1, 6, 11, 4, 9, 2, 7, 12, 5, 10, 3, 8 + }; + + constexpr uint8_t sector_interleave2[]{ // 1-based + 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 + }; + + constexpr uint8_t sector_interleave3[]{ // 1-based + 1, 4, 7, 10, 6, 9, 12, 3, 11, 2, 5, 8 + }; + + void gcr_encode_5_to_8(const uint8_t *input, uint8_t *output) + { + // input: + // 76543210 + // -------- + // 00000111 0 + // 11222223 1 + // 33334444 2 + // 45555566 3 + // 66677777 4 + + output[0] = gcr_table[(input[0] >> 3) & 0x1f]; + output[1] = gcr_table[((input[0] << 2) & 0x1f) | ((input[1] >> 6) & 0b00000011)]; + output[2] = gcr_table[(input[1] >> 1) & 0x1f]; + output[3] = gcr_table[((input[1] << 4) & 0x1f) | ((input[2] >> 4) & 0b00001111)]; + output[4] = gcr_table[((input[2] << 1) & 0x1f) | ((input[3] >> 7) & 0b00000001)]; + output[5] = gcr_table[(input[3] >> 2) & 0x1f]; + output[6] = gcr_table[((input[3] << 3) & 0x1f) | ((input[4] >> 5) & 0b00000111)]; + output[7] = gcr_table[input[4] & 0x1f]; + } + + std::array<uint8_t, 3> checksum_256_bytes(const uint8_t *input) + { + size_t i = 0; + uint8_t a = 0; + uint8_t c = input[i++]; + uint8_t d = input[i++]; + uint8_t e = input[i++]; + for(size_t b = 0; b < 253; b++) { + a = d; + if(c & 0b10000000) + a ^= 1; + d = c; + c = a; + a = (d << 1) ^ e; + e = d; + d = a; + e ^= input[i++]; + } + + return { c, d, e }; + } + + std::array<uint8_t, 416> gcr_encode_and_checksum(const uint8_t *input /* 256 bytes */) { + std::array<uint8_t, 416> output; + for(int i = 0; i < 51; i++) + gcr_encode_5_to_8(&input[i * 5], &output[i * 8]); + + auto checksum = checksum_256_bytes(input); + std::array<uint8_t, 5> end_and_checksum{ input[255], checksum[0], checksum[1], checksum[2], 0x58 }; + gcr_encode_5_to_8(&end_and_checksum[0], &output[408]); + + return output; + } +} + +static constexpr int TRACKS_PER_DISK = 78; +static constexpr int SECTORS_PER_TRACK = 12; +static constexpr int SECTOR_SIZE = 256; + +static constexpr int RPM = 300; +static constexpr int CELLS_PER_REV = 250'000 / (RPM / 60); + +// format track: 0xaa (2), 0xaa (48), 12*sector +// format sector: sector_prefix (8), track_sync (2), sector_sync (2), predata (19), payload=0xaa (414), postdata (13), 0xaa (42), should come out to ~4,000 bits +// write sector: (after sector_sync, 0xdd) sector_header (2+14), payload (416), sector_footer (11) + +// from write_format, write_sector_data_header_data_footer +static constexpr int raw_sector_size = 8/*sector_prefix*/ + 2/*track_sync*/ + 2/*sector_sync*/ + 1/*0xdd*/ + 16/*sector_header*/ + 416/*payload*/ + 11/*sector_footer*/ + 42/*0xaa*/; +static constexpr int raw_track_size = 2/*0xaa*/ + 48/*0xaa*/ + SECTORS_PER_TRACK * raw_sector_size; + +int lw30_format::identify(util::random_read &io, uint32_t form_factor, const std::vector<uint32_t> &variants) const +{ + uint64_t size = 0; + if(io.length(size)) + return 0; + + if(size == TRACKS_PER_DISK * SECTORS_PER_TRACK * SECTOR_SIZE) + return FIFID_SIZE; // identified by size + + return 0; +} + +bool lw30_format::load(util::random_read &io, uint32_t form_factor, const std::vector<uint32_t> &variants, floppy_image &image) const +{ + uint8_t trackdata[SECTORS_PER_TRACK * SECTOR_SIZE], rawdata[CELLS_PER_REV / 8]; + memset(rawdata, 0xaa, sizeof(rawdata)); + for(int track = 0; track < TRACKS_PER_DISK; track++) { + auto const [err, actual] = read_at(io, track * SECTORS_PER_TRACK * SECTOR_SIZE, trackdata, SECTORS_PER_TRACK * SECTOR_SIZE); + if(err || (actual != SECTORS_PER_TRACK * SECTOR_SIZE)) + return false; + size_t i = 0; + for(int x = 0; x < 2 + 48; x++) + rawdata[i++] = 0xaa; + auto interleave_offset = (track % 4) * 4; + for(size_t s = interleave_offset; s < interleave_offset + SECTORS_PER_TRACK; s++) { + auto sector = sector_interleave1[s % SECTORS_PER_TRACK] - 1; + // according to check_track_and_sector + for(const auto& d : sector_prefix) // 8 bytes + rawdata[i++] = d; + put_u16le(&rawdata[i], sync_table[track]); + i += 2; + put_u16le(&rawdata[i], sync_table[sector]); + i += 2; + rawdata[i++] = 0xdd; + for(const auto& d : sector_header) // 16 bytes + rawdata[i++] = d; + auto payload = gcr_encode_and_checksum(trackdata + sector * SECTOR_SIZE); // 256 -> 416 bytes + for(const auto &d : payload) + rawdata[i++] = d; + for(const auto &d : sector_footer) // 11 bytes + rawdata[i++] = d; + for(int x = 0; x < 42; x++) + rawdata[i++] = 0xaa; + } + assert(i == raw_track_size); + assert(i <= CELLS_PER_REV / 8); + generate_track_from_bitstream(track, 0, rawdata, CELLS_PER_REV, image); + } + + image.set_variant(floppy_image::SSDD); + + return true; +} + +const char *lw30_format::name() const noexcept +{ + return "lw30"; +} + +const char *lw30_format::description() const noexcept +{ + return "Brother LW-30 floppy disk image"; +} + +const char *lw30_format::extensions() const noexcept +{ + return "img"; +} + +bool lw30_format::supports_save() const noexcept +{ + // TODO + return false; +} + +const lw30_format FLOPPY_LW30_FORMAT; |