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Merge pull request #420 from TomHarte/DSKDos33

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Corrects handling of Apple II DSK files.
This commit is contained in:
Thomas Harte 2018-05-02 21:45:56 -04:00 committed by GitHub
commit 65ba9ee6e7
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3 changed files with 28 additions and 10 deletions
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8
Storage/Disk/DiskImage/Formats/AppleDSK.cpp
View File

@ -53,12 +53,12 @@ std::shared_ptr<Track> AppleDSK::get_track_at_position(Track::Address address) {
// In either case below, the code aims for exactly 50,000 bits per track.
if(sectors_per_track_ == 16) {
// Write the sectors.
uint8_t sector_number_ = 0;
for(std::size_t c = 0; c < 16; ++c) {
std::size_t sector_number_ = 0;
for(uint8_t c = 0; c < 16; ++c) {
segment += Encodings::AppleGCR::six_and_two_sync(10);
segment += Encodings::AppleGCR::header(0, track, sector_number_);
segment += Encodings::AppleGCR::header(0, track, c);
segment += Encodings::AppleGCR::six_and_two_sync(10);
segment += Encodings::AppleGCR::six_and_two_data(&track_data[c * 256]);
segment += Encodings::AppleGCR::six_and_two_data(&track_data[sector_number_ * 256]);
// DOS and Pro DOS interleave sectors on disk, and they're represented in a disk
// image in physical order rather than logical. So that skew needs to be applied here.

9
Storage/Disk/Drive.cpp
View File

@ -205,9 +205,14 @@ void Drive::setup_track() {
assert(track_time_now >= Time(0) && current_event_.length <= Time(1));
Time time_found = track_->seek_to(track_time_now);
assert(time_found >= Time(0) && time_found < Time(1) && time_found <= track_time_now);
offset = track_time_now - time_found;
// time_found can be greater than track_time_now if limited precision caused rounding
if(time_found <= track_time_now) {
offset = track_time_now - time_found;
} else {
offset.set_zero();
}
get_next_event(offset);
}

21
Storage/Disk/Encodings/AppleGCR.cpp
View File

@ -156,13 +156,26 @@ Storage::Disk::PCMSegment AppleGCR::six_and_two_data(const uint8_t *source) {
// six bits.
const uint8_t bit_shuffle[] = {0, 2, 1, 3};
for(std::size_t c = 0; c < 84; ++c) {
segment.data[3 + c] = bit_shuffle[source[c]&3];
if(c + 86 < 256) segment.data[3 + c] |= bit_shuffle[source[c + 86]&3] << 2;
if(c + 172 < 256) segment.data[3 + c] |= bit_shuffle[source[c + 172]&3] << 4;
segment.data[3 + c] =
static_cast<uint8_t>(
bit_shuffle[source[c]&3] |
(bit_shuffle[source[c + 86]&3] << 2) |
(bit_shuffle[source[c + 172]&3] << 4)
);
}
segment.data[87] =
static_cast<uint8_t>(
(bit_shuffle[source[84]&3] << 0) |
(bit_shuffle[source[170]&3] << 2)
);
segment.data[88] =
static_cast<uint8_t>(
(bit_shuffle[source[85]&3] << 0) |
(bit_shuffle[source[171]&3] << 2)
);
for(std::size_t c = 0; c < 256; ++c) {
segment.data[3 + 85 + 1 + c] = source[c] >> 2;
segment.data[3 + 86 + c] = source[c] >> 2;
}
// Exclusive OR each byte with the one before it.