using System; using System.Collections.Generic; using System.IO; namespace BizHawk.Emulation.Cores.Computers.Commodore64.Media { public static class D64 { private static readonly int[] densityTable = { 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; private static readonly int[] gcrDecodeTable = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, //00xxx 0xFF, 0x08, 0x00, 0x01, 0xFF, 0x0C, 0x04, 0x05, //01xxx 0xFF, 0xFF, 0x02, 0x03, 0xFF, 0x0F, 0x06, 0x07, //10xxx 0xFF, 0x09, 0x0A, 0x0B, 0xFF, 0x0D, 0x0E, 0xFF //11xxx }; private static readonly int[] gcrEncodeTable = { Convert.ToByte("01010", 2), // 0 Convert.ToByte("01011", 2), // 1 Convert.ToByte("10010", 2), // 2 Convert.ToByte("10011", 2), // 3 Convert.ToByte("01110", 2), // 4 Convert.ToByte("01111", 2), // 5 Convert.ToByte("10110", 2), // 6 Convert.ToByte("10111", 2), // 7 Convert.ToByte("01001", 2), // 8 Convert.ToByte("11001", 2), // 9 Convert.ToByte("11010", 2), // A Convert.ToByte("11011", 2), // B Convert.ToByte("01101", 2), // C Convert.ToByte("11101", 2), // D Convert.ToByte("11110", 2), // E Convert.ToByte("10101", 2) // F }; private static readonly int[] sectorsPerTrack = { 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 19, 19, 19, 19, 19, 19, 19, 18, 18, 18, 18, 18, 18, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17 }; private static readonly int[] standardTrackLengthBytes = { 6250, 6666, 7142, 7692 }; private static byte Checksum(byte[] source) { var count = source.Length; byte result = 0; for (var i = 0; i < count; i++) result ^= source[i]; return result; } private static byte[] ConvertSectorToGcr(byte[] source, byte sectorNo, byte trackNo, byte formatA, byte formatB, out int bitsWritten) { var mem = new MemoryStream(); var writer = new BinaryWriter(mem); var headerChecksum = (byte)(sectorNo ^ trackNo ^ formatA ^ formatB); // assemble written data for GCR encoding var writtenData = new byte[260]; Array.Copy(source, 0, writtenData, 1, 256); writtenData[0] = 0x07; writtenData[0x101] = Checksum(source); writtenData[0x102] = 0x00; writtenData[0x103] = 0x00; writer.Write(new byte[] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }); // sync writer.Write(EncodeGcr(new byte[] { 0x08, headerChecksum, sectorNo, trackNo, formatA, formatB, 0x0F, 0x0F })); // header writer.Write(new byte[] { 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55 }); // gap writer.Write(new byte[] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }); // sync writer.Write(EncodeGcr(writtenData)); // data writer.Write(new byte[] { 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55 }); // gap bitsWritten = (int)mem.Length * 8; writer.Flush(); return mem.ToArray(); } private static byte[] EncodeGcr(byte[] source) { // 4 bytes -> 5 GCR encoded bytes var gcr = new int[8]; var data = new byte[4]; var count = source.Length; var mem = new MemoryStream(); var writer = new BinaryWriter(mem); for (var i = 0; i < count; i += 4) { Array.Copy(source, i, data, 0, 4); gcr[0] = gcrEncodeTable[data[0] >> 4]; gcr[1] = gcrEncodeTable[data[0] & 0xF]; gcr[2] = gcrEncodeTable[data[1] >> 4]; gcr[3] = gcrEncodeTable[data[1] & 0xF]; gcr[4] = gcrEncodeTable[data[2] >> 4]; gcr[5] = gcrEncodeTable[data[2] & 0xF]; gcr[6] = gcrEncodeTable[data[3] >> 4]; gcr[7] = gcrEncodeTable[data[3] & 0xF]; // -------- -------- -------- -------- -------- // 00000111 11222223 33334444 45555566 66677777 var outputValue = (gcr[0] << 3) | (gcr[1] >> 2); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[1] << 6) | (gcr[2] << 1) | (gcr[3] >> 4); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[3] << 4) | (gcr[4] >> 1); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[4] << 7) | (gcr[5] << 2) | (gcr[6] >> 3); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[6] << 5) | (gcr[7]); writer.Write((byte)(outputValue & 0xFF)); /* // -------- -------- -------- -------- -------- // 11100000 32222211 44443333 66555554 77777666 var outputValue = (gcr[0]) | (gcr[1] << 5); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[1] >> 3) | (gcr[2] << 2) | (gcr[3] << 7); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[3] >> 1) | (gcr[4] << 4); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[4] >> 4) | (gcr[5] << 1) | (gcr[6] << 6); writer.Write((byte)(outputValue & 0xFF)); outputValue = (gcr[6] >> 2) | (gcr[7] << 3); writer.Write((byte)(outputValue & 0xFF)); */ } writer.Flush(); return mem.ToArray(); } public static Disk Read(byte[] source) { var mem = new MemoryStream(source); var reader = new BinaryReader(mem); var trackDatas = new List(); var trackLengths = new List(); var trackNumbers = new List(); var trackDensities = new List(); int trackCount; switch (source.Length) { case 174848: // 35 tracks no errors trackCount = 35; break; case 175531: // 35 tracks with errors trackCount = 35; break; case 196608: // 40 tracks no errors trackCount = 40; break; case 197376: // 40 tracks with errors trackCount = 40; break; default: throw new Exception("Not able to identify capacity of the D64 file."); } for (var i = 0; i < trackCount; i++) { var sectors = sectorsPerTrack[i]; var trackLengthBits = 0; using (var trackMem = new MemoryStream()) { for (var j = 0; j < sectors; j++) { int bitsWritten; var sectorData = reader.ReadBytes(256); var diskData = ConvertSectorToGcr(sectorData, (byte)j, (byte)(i + 1), 0xA0, 0xA0, out bitsWritten); trackMem.Write(diskData, 0, diskData.Length); trackLengthBits += bitsWritten; } var density = densityTable[i]; // we pad the tracks with extra gap bytes to meet MNIB standards while (trackMem.Length < standardTrackLengthBytes[density]) { trackMem.WriteByte(0x55); } trackDatas.Add(trackMem.ToArray()); trackLengths.Add(trackLengthBits); trackNumbers.Add(i * 2); trackDensities.Add(densityTable[i]); } } return new Disk(trackDatas, trackNumbers, trackDensities, trackLengths, 84); } } }