From df56e6fe5356ebaad0d17cfa24ecae468923dd4d Mon Sep 17 00:00:00 2001 From: Thomas Harte Date: Tue, 18 Jun 2019 10:34:10 -0400 Subject: [PATCH] Fixed: the sector number also goes into sector bodies. Also the checksum is written in the other order, and the final byte of data isn't output. --- .../Mac/Clock SignalTests/MacGCRTests.mm | 2 +- Storage/Disk/DiskImage/Formats/DiskCopy42.cpp | 8 +++--- Storage/Disk/Encodings/AppleGCR/Encoder.cpp | 26 ++++++++++++------- Storage/Disk/Encodings/AppleGCR/Encoder.hpp | 4 +-- 4 files changed, 24 insertions(+), 16 deletions(-) diff --git a/OSBindings/Mac/Clock SignalTests/MacGCRTests.mm b/OSBindings/Mac/Clock SignalTests/MacGCRTests.mm index b966525ce..7c1f070f7 100644 --- a/OSBindings/Mac/Clock SignalTests/MacGCRTests.mm +++ b/OSBindings/Mac/Clock SignalTests/MacGCRTests.mm @@ -127,7 +127,7 @@ 0x09, 0x64, 0x18, 0x6e, 0x66, 0xd5, 0x32, 0x6f, 0xc2, 0x1e, 0x69, 0x75, 0x80, 0x4d, 0x9e, 0x92, 0x5a, 0xee, 0xc1, 0x29, 0x41, 0xae, 0x47, 0xbd, 0x3b, 0x13, 0x46, 0xa1, }; - const auto data = Storage::Encodings::AppleGCR::Macintosh::data(source_data); + const auto data = Storage::Encodings::AppleGCR::Macintosh::data(0, source_data); const auto expected = Storage::Disk::PCMSegment(expected_data); XCTAssertEqual(data.data, expected.data); } diff --git a/Storage/Disk/DiskImage/Formats/DiskCopy42.cpp b/Storage/Disk/DiskImage/Formats/DiskCopy42.cpp index fb02a08d3..eda8445e6 100644 --- a/Storage/Disk/DiskImage/Formats/DiskCopy42.cpp +++ b/Storage/Disk/DiskImage/Formats/DiskCopy42.cpp @@ -136,6 +136,9 @@ std::shared_ptr<::Storage::Disk::Track> DiskCopy42::get_track_at_position(::Stor segment += Encodings::AppleGCR::six_and_two_sync(24); for(int c = 0; c < included_sectors.length; ++c) { +// 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); + uint8_t sector_plus_tags[524]; // Copy in the tags, if provided; otherwise generate them. @@ -155,12 +158,9 @@ std::shared_ptr<::Storage::Disk::Track> DiskCopy42::get_track_at_position(::Stor // 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::Macintosh::data(sector_id, sector_plus_tags); segment += Encodings::AppleGCR::six_and_two_sync(20); } diff --git a/Storage/Disk/Encodings/AppleGCR/Encoder.cpp b/Storage/Disk/Encodings/AppleGCR/Encoder.cpp index 8a4b24a3e..60201e318 100644 --- a/Storage/Disk/Encodings/AppleGCR/Encoder.cpp +++ b/Storage/Disk/Encodings/AppleGCR/Encoder.cpp @@ -232,7 +232,7 @@ Storage::Disk::PCMSegment AppleGCR::Macintosh::header(uint8_t type, uint8_t trac return Storage::Disk::PCMSegment(data); } -Storage::Disk::PCMSegment AppleGCR::Macintosh::data(const uint8_t *source) { +Storage::Disk::PCMSegment AppleGCR::Macintosh::data(uint8_t sector, const uint8_t *source) { std::vector output(710); int checksum[3] = {0, 0, 0}; @@ -241,6 +241,9 @@ Storage::Disk::PCMSegment AppleGCR::Macintosh::data(const uint8_t *source) { output[1] = data_prologue[1]; output[2] = data_prologue[2]; + // Add the sector number. + output[3] = six_and_two_mapping[sector & 0x3f]; + // The Macintosh has a similar checksum-as-it-goes approach to encoding // to the Apple II, but works entirely differently. Each three bytes of // input are individually encoded to four GCR bytes, their output values @@ -284,10 +287,10 @@ Storage::Disk::PCMSegment AppleGCR::Macintosh::data(const uint8_t *source) { // Having mutated those three bytes according to the current checksum, // and the checksum according to those bytes, run them through the // GCR conversion table. - output[3 + c*4 + 1] = six_and_two_mapping[values[0] & 0x3f]; - output[3 + c*4 + 2] = six_and_two_mapping[values[1] & 0x3f]; - output[3 + c*4 + 3] = six_and_two_mapping[values[2] & 0x3f]; - output[3 + c*4 + 0] = six_and_two_mapping[ + output[4 + c*4 + 1] = six_and_two_mapping[values[0] & 0x3f]; + output[4 + c*4 + 2] = six_and_two_mapping[values[1] & 0x3f]; + output[4 + c*4 + 3] = six_and_two_mapping[values[2] & 0x3f]; + output[4 + c*4 + 0] = six_and_two_mapping[ ((values[0] >> 2) & 0x30) | ((values[1] >> 4) & 0x0c) | ((values[2] >> 6) & 0x03) @@ -295,13 +298,18 @@ Storage::Disk::PCMSegment AppleGCR::Macintosh::data(const uint8_t *source) { } // Also write the checksum. - output[704] = six_and_two_mapping[checksum[0] & 0x3f]; + // + // Caveat: the first byte written here will overwrite the final byte that + // was deposited in the loop above. That's deliberate. The final byte from + // the loop above doesn't contain any useful content, and isn't actually + // included on disk. + output[704] = six_and_two_mapping[checksum[2] & 0x3f]; output[705] = six_and_two_mapping[checksum[1] & 0x3f]; - output[706] = six_and_two_mapping[checksum[2] & 0x3f]; + output[706] = six_and_two_mapping[checksum[0] & 0x3f]; output[703] = six_and_two_mapping[ - ((checksum[0] >> 2) & 0x30) | + ((checksum[2] >> 2) & 0x30) | ((checksum[1] >> 4) & 0x0c) | - ((checksum[2] >> 6) & 0x03) + ((checksum[0] >> 6) & 0x03) ]; // Write epilogue. diff --git a/Storage/Disk/Encodings/AppleGCR/Encoder.hpp b/Storage/Disk/Encodings/AppleGCR/Encoder.hpp index 85b9f141c..300f70dad 100644 --- a/Storage/Disk/Encodings/AppleGCR/Encoder.hpp +++ b/Storage/Disk/Encodings/AppleGCR/Encoder.hpp @@ -55,9 +55,9 @@ SectorSpan sectors_in_track(int track); /*! Produces the data section of a Macintosh-format sector; the segment returned will be 5680 bits long, encoding the first 524 bytes - from @c source. + from @c source and including a record of the @c sector. */ -Storage::Disk::PCMSegment data(const uint8_t *source); +Storage::Disk::PCMSegment data(uint8_t sector, const uint8_t *source); /*! Produces the Mac-standard header. This is the same