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On second thoughts, no need to use a vector here.

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This commit is contained in:
Thomas Harte 2022-01-01 17:15:12 -05:00
parent d3189acaa6
commit 38dd3c5c60
2 changed files with 30 additions and 27 deletions
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55
Storage/Disk/DiskImage/Formats/IPF.cpp
View File

@ -292,61 +292,64 @@ 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.
/// @returns The correct bit length for @c block on a track of @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.
}
Storage::Time IPF::bit_length(TrackDescription::Density density, int block) {
constexpr unsigned int us = 100'000'000;
static constexpr auto us170 = Storage::Time::simplified(170, us);
static constexpr auto us180 = Storage::Time::simplified(180, us);
static constexpr auto us189 = Storage::Time::simplified(189, us);
static constexpr auto us190 = Storage::Time::simplified(190, us);
static constexpr auto us199 = Storage::Time::simplified(199, us);
static constexpr auto us200 = Storage::Time::simplified(200, us);
static constexpr auto us209 = Storage::Time::simplified(209, us);
static constexpr auto us210 = Storage::Time::simplified(210, us);
static constexpr auto us220 = Storage::Time::simplified(220, us);
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
if(block == 4) return us189;
if(block == 5) return us199;
if(block == 6) return us209;
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
if(block == 0) return us189;
if(block == 1) return us199;
if(block == 2) return us209;
break;
case TrackDescription::Density::CopylockST:
if(blocks > 5) result[5] = Storage::Time(21, 10'000'000); // 2.1µs
if(block == 5) return us210;
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
if(block == 1) return us220;
if(block == 2) return us180;
break;
case TrackDescription::Density::OldSpeedlockAmiga:
if(blocks > 1) result[1] = Storage::Time(21, 10'000'000); // 2.1µs
if(block == 1) return us210;
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
if(block == 1) return us220;
if(block == 2) return us210;
if(block == 3) return us200;
if(block == 4) return us190;
if(block == 5) return us180;
if(block == 6) return us170;
break;
// TODO: AdamBrierleyDensityKeyAmiga.
}
return result;
return us200; // i.e. default to 2µs.
}

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

@ -68,7 +68,7 @@ class IPF: public DiskImage, public TargetPlatform::TypeDistinguisher {
bool has_fuzzy_bits = false;
};
std::vector<Time> bit_lengths(TrackDescription::Density, size_t blocks);
Time bit_length(TrackDescription::Density, int block);
int head_count_;
int track_count_;