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Makes at least some attempt at producing real disk tracks.

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This commit is contained in:
Thomas Harte 2019-06-16 21:17:24 -04:00
parent 5c8aacdc17
commit 05c2854dbc
1 changed files with 53 additions and 1 deletions
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54
Storage/Disk/DiskImage/Formats/DiskCopy42.cpp
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@ -8,6 +8,9 @@
#include "DiskCopy42.hpp"
#include "../../Track/PCMTrack.hpp"
#include "../../Encodings/AppleGCR/Encoder.hpp"
/*
File format specifications as referenced below are largely
sourced from the documentation at
@ -36,6 +39,10 @@ DiskCopy42::DiskCopy42(const std::string &file_name) :
const auto data_checksum = file_.get32be();
const auto tag_checksum = file_.get32be();
// Don't continue with no data.
if(!data_block_length)
throw Error::InvalidFormat;
// Check that this is a comprehensible disk encoding.
const auto encoding = file_.get8();
switch(encoding) {
@ -115,6 +122,51 @@ std::shared_ptr<::Storage::Disk::Track> DiskCopy42::get_track_at_position(::Stor
Bit 5 indicates double sided or not.
*/
// TODO.
if(encoding_ == Encoding::GCR400 || encoding_ == Encoding::GCR800) {
// Perform a GCR encoding.
const auto included_sectors = Storage::Encodings::AppleGCR::Macintosh::sectors_in_track(address.position.as_int());
const size_t start_sector = size_t(included_sectors.start * get_head_count() + included_sectors.length * address.head);
if(start_sector*512 >= data_.size()) return nullptr;
uint8_t *sector = &data_[512 * start_sector];
uint8_t *tags = tags_.size() ? nullptr : &tags_[12 * start_sector];
Storage::Disk::PCMSegment segment;
segment += Encodings::AppleGCR::six_and_two_sync(24);
for(int c = 0; c < included_sectors.length; ++c) {
uint8_t sector_plus_tags[524];
// Copy in the sector body.
memcpy(sector_plus_tags, sector, 512);
sector += 512;
// Copy in the tags, if provided; otherwise generate them.
if(tags) {
memcpy(&sector_plus_tags[512], tags, 12);
tags += 12;
} else {
// TODO: generate tags.
}
// NB: sync lengths below are identical to those for
// the Apple II, as I have no idea whatsoever what they
// should be.
// const int interleave_scale = ((format_ & 0x1f) == 4) ? 8 : 4;
uint8_t sector_id = uint8_t(c);//uint8_t((c == included_sectors.length - 1) ? c : (c * interleave_scale)%included_sectors.length);
segment += Encodings::AppleGCR::Macintosh::header(0x22, uint8_t(address.position.as_int()), sector_id, !!address.head);
segment += Encodings::AppleGCR::six_and_two_sync(7);
segment += Encodings::AppleGCR::Macintosh::data(sector_plus_tags);
segment += Encodings::AppleGCR::six_and_two_sync(20);
}
// TODO: is there inter-track skew?
return std::make_shared<PCMTrack>(segment);
}
return nullptr;
}