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|
// license:BSD-3-Clause
// copyright-holders:Nathan Woods, Wilbert Pol
/***************************************************************************
fs_coco_rsdos.cpp
Management of CoCo "RS-DOS" floppy images
Limitation:
- The determination of the file type is very limited.
***************************************************************************/
#include "fs_coco_rsdos.h"
#include "coco_rawdsk.h"
#include "fsblk.h"
#include "util/strformat.h"
#include <bitset>
#include <optional>
#include <regex>
#include <string_view>
using namespace fs;
namespace fs { const coco_rsdos_image COCO_RSDOS; }
namespace {
class coco_rsdos_impl : public filesystem_t
{
public:
coco_rsdos_impl(fsblk_t &blockdev);
virtual ~coco_rsdos_impl() = default;
static constexpr int SECTOR_DIRECTORY_ENTRY_COUNT = 8;
struct rsdos_dirent
{
char m_filename[11];
u8 m_filetype;
u8 m_asciiflag;
u8 m_first_granule;
u8 m_last_sector_bytes_msb;
u8 m_last_sector_bytes_lsb;
};
struct rsdos_dirent_sector
{
struct
{
rsdos_dirent m_dirent;
u8 m_unused[16];
} m_entries[SECTOR_DIRECTORY_ENTRY_COUNT];
};
class granule_iterator
{
public:
granule_iterator(coco_rsdos_impl &fs, const rsdos_dirent &dirent);
bool next(u8 &granule, u16 &byte_count);
private:
fsblk_t::block_t m_granule_map;
std::optional<u8> m_current_granule;
u8 m_maximum_granules;
u16 m_last_sector_bytes;
std::bitset<256> m_visited_granules;
};
virtual std::pair<err_t, meta_data> metadata(const std::vector<std::string> &path) override;
virtual std::pair<err_t, std::vector<dir_entry>> directory_contents(const std::vector<std::string> &path) override;
virtual std::pair<err_t, std::vector<u8>> file_read(const std::vector<std::string> &path) override;
virtual err_t format(const meta_data &meta) override;
virtual err_t file_create(const std::vector<std::string> &path, const meta_data &meta) override;
virtual err_t file_write(const std::vector<std::string> &path, const std::vector<u8> &data) override;
static bool validate_filename(std::string_view name);
private:
static constexpr u8 TRACK_GRANULE_COUNT = 2;
static constexpr u8 GRANULE_SECTOR_COUNT = 9;
static constexpr u8 TRACK_SECTOR_COUNT = TRACK_GRANULE_COUNT * GRANULE_SECTOR_COUNT;
static constexpr u8 DIRECTORY_TRACK = 17;
static constexpr u8 DIRECTORY_ENTRY_SIZE = 0x20;
static constexpr u8 FNAME_LENGTH = 11;
static constexpr u16 SECTOR_SIZE = 0x100;
static constexpr u8 OFFSET_FILE_TYPE = 0x0b;
static constexpr u8 OFFSET_ASCII_FLAG = 0x0c;
static constexpr u8 OFFSET_FIRST_GRANULE = 0x0d;
static constexpr u8 OFFSET_LAST_SECTOR_BYTES = 0x0e;
static constexpr u8 FILE_TYPE_BASIC = 0x00;
static constexpr u8 FILE_TYPE_BASIC_DATA = 0x01;
static constexpr u8 FILE_TYPE_MACHINE_CODE = 0x02;
static constexpr u8 FILE_TYPE_TEXT_EDITOR = 0x03;
static constexpr u8 FILE_LAST_GRANULE_INDICATOR = 0xc0;
fsblk_t::block_t read_sector(int track, int sector) const;
fsblk_t::block_t read_granule_sector(u8 granule, u8 sector) const;
u8 maximum_granules() const;
std::optional<rsdos_dirent> dirent_from_path(const std::vector<std::string> &path);
template <typename T>
void iterate_directory_entries(T &&callback);
meta_data get_metadata_from_dirent(const rsdos_dirent &dirent);
static std::string get_filename_from_dirent(const rsdos_dirent &dirent);
std::pair<err_t, std::string> build_direntry_filename(const std::string &filename);
std::pair<err_t, u8> claim_granule();
void write_granule_map(u8 granule, u8 map_data);
u8 read_granule_map(u8 granule) const;
bool is_ascii(const std::vector<u8> &data) const;
u8 determine_file_type(const std::vector<u8> &data) const;
};
} // anonymous namespace
//-------------------------------------------------
// name
//-------------------------------------------------
const char *coco_rsdos_image::name() const
{
return "coco_rsdos";
}
//-------------------------------------------------
// description
//-------------------------------------------------
const char *coco_rsdos_image::description() const
{
return "CoCo RS-DOS";
}
//-------------------------------------------------
// enumerate_f
//-------------------------------------------------
void coco_rsdos_image::enumerate_f(floppy_enumerator &fe) const
{
fe.add(FLOPPY_COCO_RAWDSK_FORMAT, floppy_image::FF_525, floppy_image::SSSD, 161280, "coco_rawdsk_rsdos_35", "CoCo Raw Disk RS-DOS single-sided 35 tracks");
fe.add(FLOPPY_COCO_RAWDSK_FORMAT, floppy_image::FF_525, floppy_image::SSSD, 184320, "coco_rawdsk_rsdos_40", "CoCo Raw Disk RS-DOS single-sided 40 tracks");
}
//-------------------------------------------------
// can_format
//-------------------------------------------------
bool coco_rsdos_image::can_format() const
{
return true;
}
//-------------------------------------------------
// can_read
//-------------------------------------------------
bool coco_rsdos_image::can_read() const
{
return true;
}
//-------------------------------------------------
// can_write
//-------------------------------------------------
bool coco_rsdos_image::can_write() const
{
return true;
}
//-------------------------------------------------
// has_rsrc
//-------------------------------------------------
bool coco_rsdos_image::has_rsrc() const
{
return false;
}
//-------------------------------------------------
// file_meta_description
//-------------------------------------------------
std::vector<meta_description> coco_rsdos_image::file_meta_description() const
{
std::vector<meta_description> results;
results.emplace_back(meta_description(meta_name::name, "", false, [](const meta_value &m) { return coco_rsdos_impl::validate_filename(m.as_string()); }, "File name, 8.3"));
results.emplace_back(meta_description(meta_name::file_type, 0, true, nullptr, "Type of the file"));
results.emplace_back(meta_description(meta_name::ascii_flag, "B", true, nullptr, "Ascii or binary flag"));
results.emplace_back(meta_description(meta_name::size_in_blocks, 0, true, nullptr, "Number of granules used by the file"));
results.emplace_back(meta_description(meta_name::length, 0, true, nullptr, "Size of the file in bytes"));
return results;
}
//-------------------------------------------------
// mount
//-------------------------------------------------
std::unique_ptr<filesystem_t> coco_rsdos_image::mount(fsblk_t &blockdev) const
{
return std::make_unique<coco_rsdos_impl>(blockdev);
}
//-------------------------------------------------
// validate_filename
//-------------------------------------------------
bool coco_rsdos_impl::validate_filename(std::string_view name)
{
auto pos = name.find('.');
auto stem_length = pos != std::string::npos ? pos : name.size();
auto ext_length = pos != std::string::npos ? name.size() - pos - 1 : 0;
return stem_length > 0 && stem_length <= 8 && ext_length <= 3;
}
//-------------------------------------------------
// coco_rsdos_impl ctor
//-------------------------------------------------
coco_rsdos_impl::coco_rsdos_impl(fsblk_t &blockdev)
: filesystem_t(blockdev, SECTOR_SIZE)
{
}
//-------------------------------------------------
// coco_rsdos_impl::metadata
//-------------------------------------------------
std::pair<err_t, meta_data> coco_rsdos_impl::metadata(const std::vector<std::string> &path)
{
// attempt to find the file
const std::optional<rsdos_dirent> dirent = dirent_from_path(path);
if (!dirent)
return std::make_pair(ERR_NOT_FOUND, meta_data());
return std::make_pair(ERR_OK, get_metadata_from_dirent(*dirent));
}
//-------------------------------------------------
// coco_rsdos_impl::directory_contents
//-------------------------------------------------
std::pair<err_t, std::vector<dir_entry>> coco_rsdos_impl::directory_contents(const std::vector<std::string> &path)
{
std::vector<dir_entry> results;
auto const callback = [this, &results](u8 s, u8 i, const rsdos_dirent &dirent)
{
results.emplace_back(dir_entry_type::file, get_metadata_from_dirent(dirent));
return false;
};
iterate_directory_entries(callback);
return std::make_pair(ERR_OK, std::move(results));
}
//-------------------------------------------------
// coco_rsdos_impl::file_read
//-------------------------------------------------
std::pair<err_t, std::vector<u8>> coco_rsdos_impl::file_read(const std::vector<std::string> &path)
{
// attempt to find the file
const std::optional<rsdos_dirent> dirent = dirent_from_path(path);
if (!dirent)
return std::make_pair(ERR_NOT_FOUND, std::vector<u8>());
std::vector<u8> result;
u8 granule;
u16 byte_count;
granule_iterator iter(*this, *dirent);
while (iter.next(granule, byte_count))
{
// resize the results
size_t current_size = result.size();
result.resize(current_size + byte_count);
// determine which track and sector this granule starts at
int track = granule / 2 + (granule >= 34 ? 1 : 0);
int sector = granule % 2 * 9 + 1;
// and read all the sectors
while (byte_count > 0)
{
// read this sector
auto block = read_sector(track, sector);
const u8 *data = block.rodata();
u16 data_length = std::min(byte_count, u16(SECTOR_SIZE));
// and append it to the results
memcpy(result.data() + current_size, data, data_length);
// and advance
current_size += data_length;
byte_count -= data_length;
sector++;
}
}
return std::make_pair(ERR_OK, std::move(result));
}
//-------------------------------------------------
// coco_rsdos_impl::format
//-------------------------------------------------
err_t coco_rsdos_impl::format(const meta_data &meta)
{
// formatting RS-DOS is easy - just fill everything with 0xFF
m_blockdev.fill(0xFF);
return ERR_OK;
}
std::pair<err_t, std::string> coco_rsdos_impl::build_direntry_filename(const std::string &filename)
{
// The manual does not say anything about valid characters for a file name.
const std::regex filename_regex("([^.]{0,8})(\\.([^.]{0,3}))?");
std::smatch smatch;
if (!std::regex_match(filename, smatch, filename_regex))
return std::make_pair(ERR_INVALID, std::string());
if (smatch.size() != 4)
return std::make_pair(ERR_INVALID, std::string());
std::string fname;
fname.resize(FNAME_LENGTH, ' ');
for (int i = 0; i < 8 && i < smatch.str(1).size(); i++)
fname[i] = smatch.str(1)[i];
for (int j = 0; j < 3 && j < smatch.str(3).size(); j++)
fname[8 + j] = smatch.str(3)[j];
return std::make_pair(ERR_OK, std::move(fname));
}
err_t coco_rsdos_impl::file_create(const std::vector<std::string> &path, const meta_data &meta)
{
if (!path.empty())
return ERR_UNSUPPORTED;
const std::string filename = meta.get_string(meta_name::name, "");
auto [err, fname] = build_direntry_filename(filename);
if (err != ERR_OK)
return err;
bool found_entry = false;
u8 dir_sector = 0;
u8 file_index = 0;
for (dir_sector = 3; !found_entry && dir_sector <= TRACK_SECTOR_COUNT; dir_sector++)
{
auto dir_block = read_sector(DIRECTORY_TRACK, dir_sector);
for (file_index = 0; !found_entry && file_index < SECTOR_DIRECTORY_ENTRY_COUNT; file_index++)
{
const u8 first_byte = dir_block.r8(file_index * DIRECTORY_ENTRY_SIZE);
// 0xff marks the end of the directory, 0x00 marks a deleted file
found_entry = (first_byte == 0xff || first_byte == 0x00);
if (found_entry)
{
for (int i = 0; i < DIRECTORY_ENTRY_SIZE; i++)
dir_block.w8(file_index * DIRECTORY_ENTRY_SIZE + i, 0);
auto [cerr, granule] = claim_granule();
if (cerr != ERR_OK)
return cerr;
dir_block.wstr(file_index * DIRECTORY_ENTRY_SIZE + 0, fname);
dir_block.w8(file_index * DIRECTORY_ENTRY_SIZE + OFFSET_FIRST_GRANULE, granule);
// The file type, ascii flag, and number of bytes in last sector of file will be set during writing.
}
}
}
if (!found_entry)
return ERR_NO_SPACE;
return ERR_OK;
}
err_t coco_rsdos_impl::file_write(const std::vector<std::string> &path, const std::vector<u8> &data)
{
if (path.size() != 1)
return ERR_NOT_FOUND;
const std::string &target = path[0];
std::optional<rsdos_dirent> result;
u8 dir_sector = 0;
u8 dir_file_index = 0;
auto const callback = [&result, &target, &dir_sector, &dir_file_index](u8 s, u8 i, const rsdos_dirent &dirent)
{
const bool found = get_filename_from_dirent(dirent) == target;
if (found)
{
result = dirent;
dir_sector = s;
dir_file_index = i;
}
return found;
};
iterate_directory_entries(callback);
if (!result)
return ERR_NOT_FOUND;
const size_t data_length = data.size();
const u8 max_granule = maximum_granules();
u8 granule = result->m_first_granule;
u8 granule_sector = 1;
size_t offset = 0;
u16 bytes_in_last_sector = 0;
u8 linked_granule = read_granule_map(granule);
while (offset < data_length)
{
auto data_block = read_granule_sector(granule, granule_sector);
bytes_in_last_sector = (data_length - offset) > SECTOR_SIZE ? SECTOR_SIZE : data_length - offset;
memcpy(data_block.data(), data.data() + offset, bytes_in_last_sector);
offset += SECTOR_SIZE;
write_granule_map(granule, FILE_LAST_GRANULE_INDICATOR + granule_sector);
if (offset < data_length)
{
granule_sector++;
if (granule_sector > GRANULE_SECTOR_COUNT)
{
// Re-use linked granule or claim a new granule
if (linked_granule < max_granule)
{
granule = linked_granule;
linked_granule = read_granule_map(linked_granule);
}
else
{
auto [err, next_granule] = claim_granule();
if (err != ERR_OK)
return err;
write_granule_map(granule, next_granule);
granule = next_granule;
}
granule_sector = 1;
}
}
}
// Free unused space
while (linked_granule < max_granule)
{
const u8 granule_to_free = linked_granule;
linked_granule = read_granule_map(granule_to_free);
write_granule_map(granule_to_free, 0xff);
}
// Update directory entry
auto dir_block = read_sector(DIRECTORY_TRACK, dir_sector);
dir_block.w8(dir_file_index * DIRECTORY_ENTRY_SIZE + OFFSET_FILE_TYPE, determine_file_type(data));
dir_block.w8(dir_file_index * DIRECTORY_ENTRY_SIZE + OFFSET_ASCII_FLAG, is_ascii(data) ? 0xff : 0x00);
dir_block.w16b(dir_file_index * DIRECTORY_ENTRY_SIZE + OFFSET_LAST_SECTOR_BYTES, bytes_in_last_sector);
return ERR_OK;
}
bool coco_rsdos_impl::is_ascii(const std::vector<u8> &data) const
{
const size_t data_length = data.size();
if (data_length == 0)
return false;
for (int i = 0; i < data_length; i++)
{
if (!(data[i] == 0x0d || data[i] == 0x0a || (data[i] >= 0x20 && data[i] < 0x60)))
return false;
}
return true;
}
u8 coco_rsdos_impl::determine_file_type(const std::vector<u8> &data) const
{
if (is_ascii(data))
{
// TODO: Distinguish between basic code and text editor data
return FILE_TYPE_BASIC;
}
const size_t data_length = data.size();
// Binary basic code seems to begin with ff <16bit size> 26
if (data_length > 4 && data[0] == 0xff && data[3] == 0x26 && ((data[1] << 8) | data[2]) == data_length - 3)
return FILE_TYPE_BASIC;
// TODO: Distinguish between Machine Code and Basic Data
return FILE_TYPE_MACHINE_CODE;
}
std::pair<err_t, u8> coco_rsdos_impl::claim_granule()
{
// Granules are likely not assigned in this order on hardware.
auto granule_block = read_sector(DIRECTORY_TRACK, 2);
for (int g = 0; g < maximum_granules(); g++)
{
if (granule_block.r8(g) == 0xff)
{
granule_block.w8(g, FILE_LAST_GRANULE_INDICATOR);
return std::make_pair(ERR_OK, g);
}
}
return std::make_pair(ERR_NO_SPACE, 0);
}
void coco_rsdos_impl::write_granule_map(u8 granule, u8 map_data)
{
auto granule_block = read_sector(DIRECTORY_TRACK, 2);
granule_block.w8(granule, map_data);
}
u8 coco_rsdos_impl::read_granule_map(u8 granule) const
{
auto granule_block = read_sector(DIRECTORY_TRACK, 2);
return granule_block.r8(granule);
}
//-------------------------------------------------
// fsblk_t::block_t coco_rsdos_impl::read_sector
//-------------------------------------------------
fsblk_t::block_t coco_rsdos_impl::read_sector(int track, int sector) const
{
// the CoCo RS-DOS world thinks in terms of tracks/sectors, but we have a block device
// abstraction
return m_blockdev.get(track * TRACK_SECTOR_COUNT + sector - 1);
}
fsblk_t::block_t coco_rsdos_impl::read_granule_sector(u8 granule, u8 sector) const
{
// Track 17 does not hold granules
if (granule < (DIRECTORY_TRACK * TRACK_GRANULE_COUNT))
return m_blockdev.get(granule * GRANULE_SECTOR_COUNT + sector - 1);
else
return m_blockdev.get((granule + TRACK_GRANULE_COUNT) * GRANULE_SECTOR_COUNT + sector - 1);
}
//-------------------------------------------------
// coco_rsdos_impl::maximum_granules
//-------------------------------------------------
u8 coco_rsdos_impl::maximum_granules() const
{
u32 sector_count = m_blockdev.block_count();
u32 granule_count = (sector_count / GRANULE_SECTOR_COUNT) - 2;
return granule_count <= 0xFF ? u8(granule_count) : 0xFF;
}
//-------------------------------------------------
// coco_rsdos_impl::dirent_from_path
//-------------------------------------------------
std::optional<coco_rsdos_impl::rsdos_dirent> coco_rsdos_impl::dirent_from_path(const std::vector<std::string> &path)
{
if (path.size() != 1)
return { };
const std::string &target = path[0];
std::optional<rsdos_dirent> result;
auto const callback = [&result, &target](u8 s, u8 i, const rsdos_dirent &dirent)
{
bool found = get_filename_from_dirent(dirent) == target;
if (found)
result = dirent;
return found;
};
iterate_directory_entries(callback);
return result;
}
//-------------------------------------------------
// coco_rsdos_impl::iterate_directory_entries
//-------------------------------------------------
template <typename T>
void coco_rsdos_impl::iterate_directory_entries(T &&callback)
{
bool done = false;
for (int dir_sector = 3; !done && dir_sector <= 18; dir_sector++)
{
// read this directory sector
auto dir_block = read_sector(DIRECTORY_TRACK, dir_sector);
const rsdos_dirent_sector §or = *reinterpret_cast<const rsdos_dirent_sector *>(dir_block.rodata());
// and loop through all entries
for (int file_index = 0; file_index < 8; file_index++)
{
// 0xFF marks the end of the directory
if (sector.m_entries[file_index].m_dirent.m_filename[0] == '\xFF')
{
done = true;
}
else
{
// 0x00 marks a deleted file
if (sector.m_entries[file_index].m_dirent.m_filename[0] != '\0')
done = callback(dir_sector, 0, sector.m_entries[file_index].m_dirent);
}
if (done)
break;
}
}
}
//-------------------------------------------------
// coco_rsdos_impl::get_metadata_from_dirent
//-------------------------------------------------
meta_data coco_rsdos_impl::get_metadata_from_dirent(const rsdos_dirent &dirent)
{
u32 file_size = 0;
int granule_count = 0;
// we need to iterate on the file to determine the size and granule/block count
u8 granule;
u16 byte_count;
granule_iterator iter(*this, dirent);
while (iter.next(granule, byte_count))
{
granule_count++;
file_size += byte_count;
}
// determine the file name
std::string name = get_filename_from_dirent(dirent);
// turn the ASCII flag to a single character (this reflects what the user sees when doing a directory listing on a real CoCo)
char file_type_char = 'B' + dirent.m_asciiflag;
// build the metadata and return it
meta_data result;
result.set(meta_name::name, std::move(name));
result.set(meta_name::file_type, dirent.m_filetype);
result.set(meta_name::ascii_flag, std::string(1, file_type_char));
result.set(meta_name::size_in_blocks, granule_count);
result.set(meta_name::length, file_size);
return result;
}
//-------------------------------------------------
// coco_rsdos_impl::get_filename_from_dirent
//-------------------------------------------------
std::string coco_rsdos_impl::get_filename_from_dirent(const rsdos_dirent &dirent)
{
std::string_view stem = trim_end_spaces(std::string_view(&dirent.m_filename[0], 8));
std::string_view ext = trim_end_spaces(std::string_view(&dirent.m_filename[8], 3));
return util::string_format("%s.%s", stem, ext);
}
//-------------------------------------------------
// coco_rsdos_impl::granule_iterator ctor
//-------------------------------------------------
coco_rsdos_impl::granule_iterator::granule_iterator(coco_rsdos_impl &fs, const rsdos_dirent &dirent)
: m_granule_map(fs.read_sector(DIRECTORY_TRACK, 2))
, m_current_granule(dirent.m_first_granule)
, m_maximum_granules(fs.maximum_granules())
, m_last_sector_bytes((u16(dirent.m_last_sector_bytes_msb) << 8) | dirent.m_last_sector_bytes_lsb)
{
// visit the first granule
m_visited_granules.set(dirent.m_first_granule);
}
//-------------------------------------------------
// coco_rsdos_impl::granule_iterator::next
//-------------------------------------------------
bool coco_rsdos_impl::granule_iterator::next(u8 &granule, u16 &byte_count)
{
bool success = false;
granule = ~0;
byte_count = 0;
if (m_current_granule)
{
std::optional<u8> next_granule;
const u8 *granule_map_data = m_granule_map.rodata();
if (granule_map_data[*m_current_granule] < m_maximum_granules)
{
// this entry points to the next granule
success = true;
granule = *m_current_granule;
byte_count = GRANULE_SECTOR_COUNT * SECTOR_SIZE;
next_granule = granule_map_data[*m_current_granule];
// check for cycles, which should only happen if the disk is corrupt (or not in RS-DOS format)
if (m_visited_granules[*next_granule])
next_granule = std::nullopt; // this is corrupt!
else
m_visited_granules.set(*next_granule);
}
else if (granule_map_data[*m_current_granule] >= FILE_LAST_GRANULE_INDICATOR && granule_map_data[*m_current_granule] <= FILE_LAST_GRANULE_INDICATOR + GRANULE_SECTOR_COUNT)
{
// this is the last granule in the file
success = true;
granule = *m_current_granule;
u16 sector_count = std::max(granule_map_data[*m_current_granule], u8(0xC1)) - 0xC1;
byte_count = sector_count * SECTOR_SIZE + m_last_sector_bytes;
next_granule = std::nullopt;
}
else
{
// should not happen; but we'll treat this as an EOF
next_granule = std::nullopt;
}
m_current_granule = next_granule;
}
return success;
}
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