Apple-2-Tools/Virtu
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Implemented reading of DSK images.

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--HG--
extra : convert_revision : svn%3Affd33b8c-2492-42e0-bdc5-587b920b7d6d/trunk%4020432
This commit is contained in:
Nick Westgate 2009-06-01 14:17:31 +00:00
parent 18ac684607
commit 9c331daffd
1 changed files with 114 additions and 2 deletions
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116
Virtu/DiskDsk.cs
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@ -11,8 +11,40 @@ public DiskDsk(string name, byte[] data, bool isWriteProtected) :
public override void ReadTrack(int number, int fraction, byte[] buffer)
{
// TODO
throw new NotImplementedException();
int track = number / 2;
_trackBuffer = buffer;
_trackOffset = 0;
WriteNibble(0xFF, 48); // gap 0
for (int sector = 0; sector < SectorCount; sector++)
{
WriteNibble(0xD5); // address prologue
WriteNibble(0xAA);
WriteNibble(0x96);
WriteNibble44(Volume);
WriteNibble44(track);
WriteNibble44(sector);
WriteNibble44(Volume ^ track ^ sector);
WriteNibble(0xDE); // address epilogue
WriteNibble(0xAA);
WriteNibble(0xEB);
WriteNibble(0xFF, 8);
WriteNibble(0xD5); // data prologue
WriteNibble(0xAA);
WriteNibble(0xAD);
WriteDataNibbles((track * SectorCount + DosOrderToLogicalSector[sector]) * SectorSize);
WriteNibble(0xDE); // data epilogue
WriteNibble(0xAA);
WriteNibble(0xEB);
WriteNibble(0xFF, 16);
}
}
public override void WriteTrack(int number, int fraction, byte[] buffer)
@ -21,6 +53,86 @@ public override void WriteTrack(int number, int fraction, byte[] buffer)
throw new NotImplementedException();
}
private void WriteNibble(int data)
{
_trackBuffer[_trackOffset++] = (byte)data;
}
private void WriteNibble(int data, int count)
{
while (count-- > 0)
{
WriteNibble(data);
}
}
private void WriteNibble44(int data)
{
WriteNibble((data >> 1) | 0xAA);
WriteNibble(data | 0xAA);
}
private void WriteDataNibbles(int sectorOffset)
{
byte a, x, y;
for (x = 0; x < SecondaryBufferLength; x++)
{
_secondaryBuffer[x] = 0; // zero secondary buffer
}
y = 2;
do // fill buffers
{
x = 0;
do
{
a = Data[sectorOffset + --y];
_secondaryBuffer[x] = (byte)((_secondaryBuffer[x] << 2) | SwapBits[a & 0x03]); // b1,b0 -> secondary buffer
_primaryBuffer[y] = (byte)(a >> 2); // b7-b2 -> primary buffer
}
while (++x < SecondaryBufferLength);
}
while (y != 0);
y = SecondaryBufferLength;
do // write secondary buffer
{
WriteNibble(ByteToNibble[_secondaryBuffer[y] ^ _secondaryBuffer[y - 1]]);
}
while (--y != 0);
a = _secondaryBuffer[0];
do // write primary buffer
{
WriteNibble(ByteToNibble[a ^ _primaryBuffer[y]]);
a = _primaryBuffer[y];
}
while (++y != 0);
WriteNibble(ByteToNibble[a]); // data checksum
}
private byte[] _trackBuffer;
private int _trackOffset;
private byte[] _primaryBuffer = new byte[0x100];
private const int SecondaryBufferLength = 0x56;
private byte[] _secondaryBuffer = new byte[SecondaryBufferLength + 1];
private const int Volume = 0xFE;
private static readonly byte[] SwapBits = { 0, 2, 1, 3 };
private static readonly int[] DosOrderToLogicalSector = new int[]
{
0x0, 0x7, 0xE, 0x6, 0xD, 0x5, 0xC, 0x4, 0xB, 0x3, 0xA, 0x2, 0x9, 0x1, 0x8, 0xF
};
private static readonly byte[] ByteToNibble = new byte[]
{
0x96, 0x97, 0x9A, 0x9B, 0x9D, 0x9E, 0x9F, 0xA6, 0xA7, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB2, 0xB3,
0xB4, 0xB5, 0xB6, 0xB7, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF, 0xCB, 0xCD, 0xCE, 0xCF, 0xD3,
0xD6, 0xD7, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF, 0xE5, 0xE6, 0xE7, 0xE9, 0xEA, 0xEB, 0xEC,
0xED, 0xEE, 0xEF, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF
};
}
}