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Relocates and cleans up what is currently written of Apple GCR handling as the encoder.

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A decoder will be forthcoming.
This commit is contained in:
Thomas Harte 2018-05-03 22:40:45 -04:00
parent 59718e132b
commit 2e20191c01
5 changed files with 69 additions and 97 deletions
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2
Storage/Disk/DiskImage/Formats/AppleDSK.cpp
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@ -9,7 +9,7 @@
#include "AppleDSK.hpp"
#include "../../Track/PCMTrack.hpp"
#include "../../Encodings/AppleGCR.hpp"
#include "../../Encodings/AppleGCR/Encoder.hpp"
using namespace Storage::Disk;

2
Storage/Disk/DiskImage/Formats/NIB.cpp
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@ -9,7 +9,7 @@
#include "NIB.hpp"
#include "../../Track/PCMTrack.hpp"
#include "../../Encodings/AppleGCR.hpp"
#include "../../Encodings/AppleGCR/Encoder.hpp"
#include <vector>

73
Storage/Disk/Encodings/AppleGCR.hpp
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@ -1,73 +0,0 @@
//
// AppleGCR.hpp
// Clock Signal
//
// Created by Thomas Harte on 21/04/2018.
// Copyright © 2018 Thomas Harte. All rights reserved.
//
#ifndef AppleGCR_hpp
#define AppleGCR_hpp
#include <cstdint>
#include "../../Disk/Track/PCMSegment.hpp"
namespace Storage {
namespace Encodings {
namespace AppleGCR {
/*!
@returns the eight-bit 13-sector GCR encoding for the low five bits of @c value.
*/
// unsigned int five_and_three_encoding_for_value(int value);
/*!
@returns the eight-bit 16-sector GCR encoding for the low six bits of @c value.
*/
// unsigned int six_and_two_encoding_for_value(int value);
/*!
A block is defined to be five source bytes, which encodes to eight GCR bytes.
*/
// void encode_five_and_three_block(uint8_t *destination, uint8_t *source);
/*!
A block is defined to be three source bytes, which encodes to four GCR bytes.
*/
// void encode_six_and_two_block(uint8_t *destination, uint8_t *source);
/*!
@returns the four bit nibble for the five-bit GCR @c quintet if a valid GCR value; INT_MAX otherwise.
*/
// unsigned int decoding_from_quintet(unsigned int quintet);
/*!
@returns the byte composed by splitting the dectet into two qintets, decoding each and composing the resulting nibbles.
*/
// unsigned int decoding_from_dectet(unsigned int dectet);
/// Describes the standard three-byte prologue that begins a header.
const uint8_t header_prologue[3] = {0xd5, 0xaa, 0x96};
/// Describes the standard three-byte prologue that begins a data section.
const uint8_t data_prologue[3] = {0xd5, 0xaa, 0xad};
/// Describes the epilogue that ends both data sections and headers.
const uint8_t epilogue[3] = {0xde, 0xaa, 0xeb};
/*!
Produces the Apple-standard '4 and 4' per-sector header. This is the same
for both the 13- and 16-sector formats, and is 112 bits long.
*/
Storage::Disk::PCMSegment header(uint8_t volume, uint8_t track, uint8_t sector);
Storage::Disk::PCMSegment six_and_two_data(const uint8_t *source);
Storage::Disk::PCMSegment six_and_two_sync(int length);
Storage::Disk::PCMSegment five_and_three_data(const uint8_t *source);
Storage::Disk::PCMSegment five_and_three_sync(int length);
}
}
}
#endif /* AppleGCR_hpp */

29
Storage/Disk/Encodings/AppleGCR.cpp → Storage/Disk/Encodings/AppleGCR/Encoder.cpp
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@ -6,11 +6,11 @@
// Copyright © 2018 Thomas Harte. All rights reserved.
//
#include "AppleGCR.hpp"
#include "Encoder.hpp"
namespace {
const unsigned int five_and_three_mapping[] = {
const uint8_t five_and_three_mapping[] = {
0xab, 0xad, 0xae, 0xaf, 0xb5, 0xb6, 0xb7, 0xba,
0xbb, 0xbd, 0xbe, 0xbf, 0xd6, 0xd7, 0xda, 0xdb,
0xdd, 0xde, 0xdf, 0xea, 0xeb, 0xed, 0xee, 0xef,
@ -53,26 +53,6 @@ Storage::Disk::PCMSegment sync(int length, int bit_size) {
using namespace Storage::Encodings;
/*void AppleGCR::encode_five_and_three_block(uint8_t *destination, uint8_t *source) {
destination[0] = static_cast<uint8_t>(five_and_three_encoding_for_value( source[0] >> 3 ));
destination[1] = static_cast<uint8_t>(five_and_three_encoding_for_value( (source[0] << 2) | (source[1] >> 6) ));
destination[2] = static_cast<uint8_t>(five_and_three_encoding_for_value( source[1] >> 1 ));
destination[3] = static_cast<uint8_t>(five_and_three_encoding_for_value( (source[1] << 4) | (source[2] >> 4) ));
destination[4] = static_cast<uint8_t>(five_and_three_encoding_for_value( (source[2] << 1) | (source[3] >> 7) ));
destination[5] = static_cast<uint8_t>(five_and_three_encoding_for_value( source[3] >> 2 ));
destination[6] = static_cast<uint8_t>(five_and_three_encoding_for_value( (source[3] << 3) | (source[4] >> 5) ));
destination[7] = static_cast<uint8_t>(five_and_three_encoding_for_value( source[4] ));
}*/
/*void AppleGCR::encode_six_and_two_block(uint8_t *destination, uint8_t *source) {
destination[0] = static_cast<uint8_t>(six_and_two_encoding_for_value( source[0] >> 2 ));
destination[1] = static_cast<uint8_t>(six_and_two_encoding_for_value( (source[0] << 4) | (source[1] >> 4) ));
destination[2] = static_cast<uint8_t>(six_and_two_encoding_for_value( (source[1] << 2) | (source[2] >> 6) ));
destination[3] = static_cast<uint8_t>(six_and_two_encoding_for_value( source[2] ));
}*/
Storage::Disk::PCMSegment AppleGCR::six_and_two_sync(int length) {
return sync(length, 10);
}
@ -132,6 +112,11 @@ Storage::Disk::PCMSegment AppleGCR::five_and_three_data(const uint8_t *source) {
// destination_pointer += 8;
// }
// Map five-bit values up to full bytes.
for(std::size_t c = 0; c < 410; ++c) {
segment.data[3 + c] = five_and_three_mapping[segment.data[3 + c]];
}
return segment;
}

60
Storage/Disk/Encodings/AppleGCR/Encoder.hpp Normal file
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@ -0,0 +1,60 @@
//
// AppleGCR.hpp
// Clock Signal
//
// Created by Thomas Harte on 21/04/2018.
// Copyright © 2018 Thomas Harte. All rights reserved.
//
#ifndef AppleGCR_hpp
#define AppleGCR_hpp
#include <cstdint>
#include "../../../Disk/Track/PCMSegment.hpp"
namespace Storage {
namespace Encodings {
namespace AppleGCR {
/// Describes the standard three-byte prologue that begins a header.
const uint8_t header_prologue[3] = {0xd5, 0xaa, 0x96};
/// Describes the standard three-byte prologue that begins a data section.
const uint8_t data_prologue[3] = {0xd5, 0xaa, 0xad};
/// Describes the epilogue that ends both data sections and headers.
const uint8_t epilogue[3] = {0xde, 0xaa, 0xeb};
/*!
Produces the Apple-standard four-and-four per-sector header. This is the same
for both the 13- and 16-sector formats, and is 112 bits long.
*/
Storage::Disk::PCMSegment header(uint8_t volume, uint8_t track, uint8_t sector);
/*!
Produces the data section of a six-and-two format sector; the segment returned
will be 2,792 bits long, encoding the first 256 bytes from @c source.
*/
Storage::Disk::PCMSegment six_and_two_data(const uint8_t *source);
/*!
Produces @c length sync six-and-two format sync bytes. The segment returned
is @c 10*length bits long.
*/
Storage::Disk::PCMSegment six_and_two_sync(int length);
/*!
Produces the data section of a five-and-three format sector; the segment returned
will be 3,336 bits long, encoding the first 256 bytes from @c source.
*/
Storage::Disk::PCMSegment five_and_three_data(const uint8_t *source);
/*!
Produces @c length sync five-and-three format sync bytes. The segment returned
is @c 9*length bits long.
*/
Storage::Disk::PCMSegment five_and_three_sync(int length);
}
}
}
#endif /* AppleGCR_hpp */