253 lines
7.4 KiB
C#
253 lines
7.4 KiB
C#
using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Text;
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namespace BizHawk.Emulation.Computers.Commodore64
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{
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public static class D64
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{
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private static int[] densityTable =
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{
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3, 3, 3, 3, 3,
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3, 3, 3, 3, 3,
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3, 3, 3, 3, 3,
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3, 3, 2, 2, 2,
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2, 2, 2, 2, 1,
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1, 1, 1, 1, 1,
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0, 0, 0, 0, 0,
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0, 0, 0, 0, 0
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};
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private static int[] gcrDecodeTable =
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{
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0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, //00xxx
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0xFF, 0x08, 0x00, 0x01, 0xFF, 0x0C, 0x04, 0x05, //01xxx
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0xFF, 0xFF, 0x02, 0x03, 0xFF, 0x0F, 0x06, 0x07, //10xxx
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0xFF, 0x09, 0x0A, 0x0B, 0xFF, 0x0D, 0x0E, 0xFF //11xxx
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};
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private static int[] gcrEncodeTable =
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{
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Convert.ToByte("01010", 2), // 0
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Convert.ToByte("01011", 2), // 1
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Convert.ToByte("10010", 2), // 2
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Convert.ToByte("10011", 2), // 3
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Convert.ToByte("01110", 2), // 4
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Convert.ToByte("01111", 2), // 5
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Convert.ToByte("10110", 2), // 6
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Convert.ToByte("10111", 2), // 7
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Convert.ToByte("01001", 2), // 8
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Convert.ToByte("11001", 2), // 9
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Convert.ToByte("11010", 2), // A
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Convert.ToByte("11011", 2), // B
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Convert.ToByte("01101", 2), // C
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Convert.ToByte("11101", 2), // D
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Convert.ToByte("11110", 2), // E
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Convert.ToByte("10101", 2) // F
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};
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private static int[] sectorsPerTrack =
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{
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21, 21, 21, 21, 21,
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21, 21, 21, 21, 21,
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21, 21, 21, 21, 21,
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21, 21, 19, 19, 19,
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19, 19, 19, 19, 18,
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18, 18, 18, 18, 18,
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17, 17, 17, 17, 17,
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17, 17, 17, 17, 17
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};
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private static int[] standardTrackLengthBytes =
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{
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6250, 6666, 7142, 7692
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};
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private static byte Checksum(byte[] source)
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{
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int count = source.Length;
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byte result = 0;
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for (int i = 0; i < count; i++)
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result ^= source[i];
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return result;
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}
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private static byte[] ConvertSectorFromGCR(byte[] source, out int bitsWritten)
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{
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bitsWritten = 0;
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return new byte[] { };
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}
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private static byte[] ConvertSectorToGCR(byte[] source, byte sectorNo, byte trackNo, byte formatA, byte formatB, out int bitsWritten)
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{
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MemoryStream mem = new MemoryStream();
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BinaryWriter writer = new BinaryWriter(mem);
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byte[] writtenData;
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byte headerChecksum = (byte)(sectorNo ^ trackNo ^ formatA ^ formatB);
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// assemble written data for GCR encoding
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writtenData = new byte[260];
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Array.Copy(source, 0, writtenData, 1, 256);
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writtenData[0] = 0x07;
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writtenData[0x101] = Checksum(source);
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writtenData[0x102] = 0x00;
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writtenData[0x103] = 0x00;
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bitsWritten = 0;
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writer.Write(new byte[] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }); // sync
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writer.Write(EncodeGCR(new byte[] { 0x08, headerChecksum, sectorNo, trackNo, formatA, formatB, 0x0F, 0x0F })); // header
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writer.Write(new byte[] { 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55 }); // gap
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writer.Write(new byte[] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }); // sync
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writer.Write(EncodeGCR(writtenData)); // data
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writer.Write(new byte[] { 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55 }); // gap
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bitsWritten = (int)mem.Length * 8;
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writer.Flush();
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return mem.ToArray();
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}
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private static byte[] DecodeGCR(byte[] source)
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{
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// 5 GCR encoded bytes -> 4 bytes
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int[] gcr = new int[8];
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byte[] data = new byte[4];
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int count = source.Length;
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int outputValue;
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MemoryStream mem = new MemoryStream();
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BinaryWriter writer = new BinaryWriter(mem);
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for (int i = 0; i < count; i += 5)
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{
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Array.Copy(source, i, data, 0, 5);
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// -------- -------- -------- -------- --------
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// 11100000 32222211 44443333 66555554 77777666
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gcr[0] = ((data[0])) & 0x1F;
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gcr[1] = ((data[0] >> 5) | data[1] << 3) & 0x1F;
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gcr[2] = ((data[1] >> 2)) & 0x1F;
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gcr[3] = ((data[1] >> 7) | data[2] << 1) & 0x1F;
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gcr[4] = ((data[2] >> 4) | data[3] << 4) & 0x1F;
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gcr[5] = ((data[3] >> 1)) & 0x1F;
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gcr[6] = ((data[3] >> 6) | data[4] << 2) & 0x1F;
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gcr[7] = ((data[4] >> 3)) & 0x1F;
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outputValue = gcrDecodeTable[gcr[0]] | (gcrDecodeTable[gcr[1]] << 4);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = gcrDecodeTable[gcr[2]] | (gcrDecodeTable[gcr[3]] << 4);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = gcrDecodeTable[gcr[4]] | (gcrDecodeTable[gcr[5]] << 4);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = gcrDecodeTable[gcr[6]] | (gcrDecodeTable[gcr[7]] << 4);
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writer.Write((byte)(outputValue & 0xFF));
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}
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writer.Flush();
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return mem.ToArray();
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}
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private static byte[] EncodeGCR(byte[] source)
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{
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// 4 bytes -> 5 GCR encoded bytes
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int[] gcr = new int[8];
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byte[] data = new byte[4];
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int count = source.Length;
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int outputValue;
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MemoryStream mem = new MemoryStream();
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BinaryWriter writer = new BinaryWriter(mem);
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for (int i = 0; i < count; i += 4)
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{
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Array.Copy(source, i, data, 0, 4);
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gcr[0] = gcrEncodeTable[data[0] & 0xF];
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gcr[1] = gcrEncodeTable[data[0] >> 4];
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gcr[2] = gcrEncodeTable[data[1] & 0xF];
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gcr[3] = gcrEncodeTable[data[1] >> 4];
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gcr[4] = gcrEncodeTable[data[2] & 0xF];
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gcr[5] = gcrEncodeTable[data[2] >> 4];
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gcr[6] = gcrEncodeTable[data[3] & 0xF];
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gcr[7] = gcrEncodeTable[data[3] >> 4];
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// -------- -------- -------- -------- --------
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// 11100000 32222211 44443333 66555554 77777666
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outputValue = (gcr[0]) | (gcr[1] << 5);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = (gcr[1] >> 3) | (gcr[2] << 2) | (gcr[3] << 7);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = (gcr[3] >> 1) | (gcr[4] << 4);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = (gcr[4] >> 4) | (gcr[5] << 1) | (gcr[6] << 6);
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writer.Write((byte)(outputValue & 0xFF));
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outputValue = (gcr[6] >> 2) | (gcr[7] << 3);
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writer.Write((byte)(outputValue & 0xFF));
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}
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writer.Flush();
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return mem.ToArray();
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}
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public static Disk Read(byte[] source)
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{
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MemoryStream mem = new MemoryStream(source);
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BinaryReader reader = new BinaryReader(mem);
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Disk result = new Disk();
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int trackCount = 0;
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switch (source.Length)
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{
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case 174848: // 35 tracks no errors
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trackCount = 35;
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break;
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case 175531: // 35 tracks with errors
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trackCount = 35;
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break;
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case 196608: // 40 tracks no errors
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trackCount = 40;
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break;
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case 197376: // 40 tracks with errors
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trackCount = 40;
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break;
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}
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for (int i = 0; i < trackCount; i++)
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{
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Track track = new Track();
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int sectors = sectorsPerTrack[i];
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MemoryStream trackMem = new MemoryStream();
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for (int j = 0; j < sectors; j++)
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{
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int bitsWritten;
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byte[] sectorData = reader.ReadBytes(256);
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byte[] diskData = ConvertSectorToGCR(sectorData, (byte)j, (byte)i, (byte)0x00, (byte)0x00, out bitsWritten);
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trackMem.Write(diskData, 0, diskData.Length);
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}
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track.density = densityTable[i];
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// we pad the tracks with extra gap bytes to meet MNIB standards
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while (trackMem.Length < standardTrackLengthBytes[track.density])
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{
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trackMem.WriteByte(0x55);
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}
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track.data = trackMem.ToArray();
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track.bits = (int)trackMem.Length;
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track.index = i;
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result.tracks.Add(track);
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trackMem.Dispose();
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}
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result.valid = (result.tracks.Count > 0);
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return result;
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}
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public static byte[] Write(Disk source)
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{
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return null;
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}
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}
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}
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