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Add those densities I've yet discovered the rules for.

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This commit is contained in:
Thomas Harte 2021-12-29 18:15:37 -05:00
parent 4f3c754771
commit 350c98ab4d
2 changed files with 61 additions and 2 deletions
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61
Storage/Disk/DiskImage/Formats/IPF.cpp
View File

@ -32,7 +32,6 @@ constexpr size_t block_size(Storage::FileHolder &file, uint8_t header) {
}
IPF::IPF(const std::string &file_name) : file_(file_name) {
std::map<uint32_t, Track::Address> tracks_by_data_key;
@ -130,7 +129,6 @@ IPF::IPF(const std::string &file_name) : file_(file_name) {
description.density = TrackDescription::Density::Unknown;
}
file_.seek(12, SEEK_CUR); // Skipped: signal type, track bytes, start byte position.
description.start_bit_pos = file_.get32be();
description.data_bits = file_.get32be();
@ -293,3 +291,62 @@ std::shared_ptr<Track> IPF::get_track_at_position([[maybe_unused]] Track::Addres
return nullptr;
}
/// @returns A vector of the length of a bit in each block for a count of @c blocks in an area of data density @c density.
///
/// @discussion At least to me, this is the least well-designed part] of the IPF specification; rather than just dictating cell
/// densities (or, equivalently, lengths) in the file, densities are named according to their protection scheme and the decoder
/// is required to know all named protection schemes. Which makes IPF unable to handle arbitrary disks (or, indeed, disks
/// with multiple protection schemes on a single track).
std::vector<Storage::Time> IPF::bit_lengths(TrackDescription::Density density, size_t blocks) {
std::vector<Storage::Time> result;
result.reserve(size_t(blocks));
// Establish the default density of 2 µs.
for(size_t c = 0; c < blocks; c++) {
result.push_back(Storage::Time(1, 500'000)); // i.e. default to 2µs.
}
switch(density) {
default:
break;
case TrackDescription::Density::CopylockAmiga:
if(blocks > 4) result[4] = Storage::Time(189, 100'000'000); // 1.89µs
if(blocks > 5) result[5] = Storage::Time(199, 100'000'000); // 1.99µs
if(blocks > 6) result[6] = Storage::Time(209, 100'000'000); // 2.09µs
break;
case TrackDescription::Density::CopylockAmigaNew:
if(blocks > 0) result[0] = Storage::Time(189, 100'000'000); // 1.89µs
if(blocks > 1) result[1] = Storage::Time(199, 100'000'000); // 1.99µs
if(blocks > 2) result[2] = Storage::Time(209, 100'000'000); // 2.09µs
break;
case TrackDescription::Density::CopylockST:
if(blocks > 5) result[5] = Storage::Time(21, 10'000'000); // 2.1µs
break;
case TrackDescription::Density::SpeedlockAmiga:
if(blocks > 1) result[1] = Storage::Time(11, 5'000'000); // 2.2µs
if(blocks > 2) result[2] = Storage::Time(9, 5'000'000); // 1.8µs
break;
case TrackDescription::Density::OldSpeedlockAmiga:
if(blocks > 1) result[1] = Storage::Time(21, 10'000'000); // 2.1µs
break;
case TrackDescription::Density::AdamBrierleyAmiga:
if(blocks > 1) result[1] = Storage::Time(11, 5'000'000); // 2.2µs
if(blocks > 2) result[2] = Storage::Time(21, 10'000'000); // 2.1µs
if(blocks > 4) result[3] = Storage::Time(19, 10'000'000); // 1.9µs
if(blocks > 5) result[5] = Storage::Time(9, 5'000'000); // 1.8µs
if(blocks > 6) result[6] = Storage::Time(17, 10'000'000); // 1.7µs
break;
// TODO: AdamBrierleyDensityKeyAmiga.
}
return result;
}

2
Storage/Disk/DiskImage/Formats/IPF.hpp
View File

@ -68,6 +68,8 @@ class IPF: public DiskImage, public TargetPlatform::TypeDistinguisher {
bool has_fuzzy_bits = false;
};
std::vector<Time> bit_lengths(TrackDescription::Density, size_t blocks);
int head_count_;
int track_count_;
std::map<Track::Address, TrackDescription> tracks_;