private byte[] ReadSectorCached(int lba)
{
//read it if we dont have it cached
//we wont be caching very much here, it's no big deal
//identification is not something we want to take a long time
byte[] data;
if (!_sectorCache.TryGetValue(lba, out data))
{
data = new byte[2048];
_dsr.ReadLBA_2048(lba, data, 0);
_sectorCache[lba] = data;
}
return(data);
}
private bool StringAt(string s, int n, int lba = 0)
{
//read it if we dont have it cached
//we wont be caching very much here, it's no big deal
//identification is not something we want to take a long time
byte[] data;
if (!sectorCache.TryGetValue(lba, out data))
{
data = new byte[2048];
dsr.ReadLBA_2048(lba, data, 0);
sectorCache[lba] = data;
}
byte[] cmp = System.Text.Encoding.ASCII.GetBytes(s);
byte[] cmp2 = new byte[cmp.Length];
Buffer.BlockCopy(data, n, cmp2, 0, cmp.Length);
return(System.Linq.Enumerable.SequenceEqual(cmp, cmp2));
}
/// <summary>
/// Easily extracts a mode1 sector range (suitable for extracting ISO FS data files)
/// </summary>
public byte[] Easy_Extract_Mode1(int lba_start, int lba_count, int byteLength = -1)
{
int totsize = lba_count * 2048;
byte[] ret = new byte[totsize];
var dsr = new DiscSectorReader(this);
dsr.Policy.DeterministicClearBuffer = false;
for (int i = 0; i < lba_count; i++)
{
dsr.ReadLBA_2048(lba_start + i, ret, i * 2048);
}
if (byteLength != -1 && byteLength != totsize)
{
byte[] newret = new byte[byteLength];
Array.Copy(ret, newret, byteLength);
return(newret);
}
return(ret);
}
//TODO - I'm not sure everything in here makes sense right now..
public override int Read(byte[] buffer, int offset, int count)
{
long remainInDisc = Length - currPosition;
if (count > remainInDisc)
{
count = (int)Math.Min(remainInDisc, int.MaxValue);
}
int remain = count;
int readed = 0;
while (remain > 0)
{
int lba = (int)(currPosition / SectorSize);
int lba_within = (int)(currPosition % SectorSize);
int todo = remain;
int remains_in_lba = SectorSize - lba_within;
if (remains_in_lba < todo)
{
todo = remains_in_lba;
}
if (cachedSector != lba)
{
dsr.ReadLBA_2048(lba, cachedSectorBuffer, 0);
cachedSector = lba;
}
Array.Copy(cachedSectorBuffer, lba_within, buffer, offset, todo);
offset += todo;
remain -= todo;
currPosition += todo;
readed += todo;
}
return(readed);
}
public void Think()
{
if (RST)
{
ResetDevice();
return;
}
if (DataReadInProgress && pce.Cpu.TotalExecutedCycles > DataReadWaitTimer)
{
if (SectorsLeftToRead > 0)
pce.DriveLightOn = true;
if (DataIn.Count == 0)
{
// read in a sector and shove it in the queue
DiscSystem.DiscSectorReader dsr = new DiscSectorReader(disc); //TODO - cache reader
dsr.ReadLBA_2048(CurrentReadingSector, DataIn.GetBuffer(), 0);
DataIn.SignalBufferFilled(2048);
CurrentReadingSector++;
SectorsLeftToRead--;
pce.IntDataTransferReady = true;
// If more sectors, should set the next think-clock to however long it takes to read 1 sector
// but I dont. I dont think transfers actually happen sector by sector
// like this, they probably become available as the bits come off the disc.
// but lets get some basic functionality before we go crazy.
// Idunno, maybe they do come in a sector at a time.
//note to vecna: maybe not at the sector level, but at a level > 1 sample and <= 1 sector, samples come out in blocks
//due to the way they are jumbled up (seriously, like put into a blender) for error correction purposes.
//we may as well assume that the cd audio decoding magic works at the level of one sector, but it isnt one sample.
if (SectorsLeftToRead == 0)
{
DataReadInProgress = false;
DataTransferWasDone = true;
}
SetPhase(BusPhase_DataIn);
}
}
do
{
signalsChanged = false;
busPhaseChanged = false;
if (SEL && !BSY)
{
SetPhase(BusPhase_Command);
}
else if (ATN && !REQ && !ACK)
{
SetPhase(BusPhase_MessageOut);
}
else switch (Phase)
{
case BusPhase_Command: ThinkCommandPhase(); break;
case BusPhase_DataIn: ThinkDataInPhase(); break;
case BusPhase_DataOut: ThinkDataOutPhase(); break;
case BusPhase_MessageIn: ThinkMessageInPhase(); break;
case BusPhase_MessageOut: ThinkMessageOutPhase(); break;
case BusPhase_Status: ThinkStatusPhase(); break;
default: break;
}
} while (signalsChanged || busPhaseChanged);
}
