/// <summary>
/// Playes back a standard speed data block entirely
/// </summary>
/// <param name="block">Data block to play back</param>
public static void CompleteBlock(this TzxStandardSpeedDataBlock block)
{
const int PILOT_PL = TapeDataBlockPlayer.PILOT_PL;
const int HEADER_PILOT_COUNT = TapeDataBlockPlayer.HEADER_PILOT_COUNT;
const int SYNC_1_PL = TapeDataBlockPlayer.SYNC_1_PL;
const int SYNC_2_PL = TapeDataBlockPlayer.SYNC_2_PL;
const long PILOT_END = PILOT_PL * HEADER_PILOT_COUNT;
const int TERM_SYNC = TapeDataBlockPlayer.TERM_SYNC;
const int PAUSE_MS = TapeDataBlockPlayer.PAUSE_MS;
var start = block.StartTact;
// --- Skip all pilot pulses + the first sync pulse
for (long pos = 0; pos < PILOT_END + SYNC_1_PL; pos += 50)
{
block.GetEarBit(start + pos);
}
// --- Skip the second sync pulse
for (var pos = PILOT_END + SYNC_1_PL + 50; pos < PILOT_END + SYNC_1_PL + SYNC_2_PL; pos += 50)
{
block.GetEarBit(start + pos);
}
// --- Play back the data
for (var i = 0; i < block.DataLength; i++)
{
block.ReadNextByte();
}
// --- Play back the terminating sync
var nextTact = block.LastTact;
for (var pos = nextTact; pos < nextTact + TERM_SYNC + 50; pos += 50)
{
block.GetEarBit(pos);
}
// --- Play back the pause
nextTact = block.LastTact;
for (var pos = nextTact; pos < nextTact + PAUSE_MS * block.PauseAfter + 100; pos += 50)
{
block.GetEarBit(pos);
}
}
/// <summary>
/// Reads the data byte from the current playback position
/// </summary>
/// <param name="block">Block to play back</param>
/// <returns>Byte read</returns>
public static byte ReadNextByte(this TzxStandardSpeedDataBlock block)
{
const int BIT_0_PL = TapeDataBlockPlayer.BIT_0_PL;
const int BIT_1_PL = TapeDataBlockPlayer.BIT_1_PL;
const int STEP = 50;
var nextTact = block.LastTact + STEP;
byte bits = 0x00;
for (var i = 0; i < 8; i++)
{
// --- Wait for the high EAR bit
var samplesLow = 0;
while (!block.GetEarBit(nextTact))
{
samplesLow++;
nextTact += STEP;
}
// --- Wait for the low EAR bit
var samplesHigh = 0;
while (block.GetEarBit(nextTact) && samplesHigh < BIT_1_PL / STEP + 2)
{
samplesHigh++;
nextTact += STEP;
}
bits <<= 1;
if (samplesLow > (BIT_0_PL + BIT_1_PL) / 2 / STEP &&
samplesHigh > (BIT_0_PL + BIT_1_PL) / 2 / STEP)
{
bits++;
}
}
return(bits);
}