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[858] IMXRT_LPSPI: Support "LSBF - LSB First" flag #214

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[858] IMXRT_LPSPI: Support "LSBF - LSB First" flag #214

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36 changes: 26 additions & 10 deletions src/Emulator/Peripherals/Peripherals/SPI/IMXRT_LPSPI.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,7 @@ private void DefineRegisters()
.WithFlag(20, out continuingCommand, name: "CONTC - Continuing Command", valueProviderCallback: _ => currentCommand?.ContinuingCommand ?? false)
.WithFlag(21, out continuousTransfer, name: "CONT - Continuous Transfer", valueProviderCallback: _ => currentCommand?.Continuous ?? false)
.WithTaggedFlag("BYSW - Byte Swap", 22)
.WithTaggedFlag("LSBF - LSB First", 23)
.WithFlag(23, out lsbFirst, name: "LSBF - LSB First", valueProviderCallback: _ => currentCommand?.LsbFirst ?? false)
.WithValueField(24, 2, name: "PCS - Peripheral Chip Select", writeCallback: (_, value) =>
{
if(!TryGetByAddress((int)value, out selectedDevice))
Expand All @@ -119,7 +119,8 @@ private void DefineRegisters()
TxMask = transmitDataMask.Value,
RxMask = receiveDataMask.Value,
Continuous = continuousTransfer.Value,
ContinuingCommand = continuingCommand.Value
ContinuingCommand = continuingCommand.Value,
LsbFirst = lsbFirst.Value
});
UpdateTransmitter();
});
Expand Down Expand Up @@ -368,24 +369,36 @@ private bool TrySendDataInner(uint value, ISPIPeripheral device)
dataMatcher.Match1 = (uint)match1.Value;
}

// we can read up to 4 bytes at a time
var byteIdx = 0;
// We can transfer up to 4 bytes at a time.
var byteCount = (int)Math.Min(sizeLeft / 8, 4u);
uint receivedWord = 0;

var lsbFirst = currentCommand.LsbFirst;

this.Log(LogLevel.Debug, "Sending 0x{0:X} to the device", value);
while(sizeLeft != 0 && byteIdx < 4)
for(var i = 0; i < byteCount; i++)
{
var resp = device.Transmit((byte)value);
var bytePos = lsbFirst ? i : byteCount - 1 - i;

var txByte = (byte)(value >> (bytePos * 8));
if(lsbFirst)
{
txByte = BitHelper.ReverseBits(txByte);
}

receivedWord |= (uint)resp << (byteIdx * 8);
var resp = device.Transmit(txByte);
if(lsbFirst)
{
resp = BitHelper.ReverseBits(resp);
}

receivedWord |= (uint)resp << (bytePos * 8);

value >>= 8;
sizeLeft -= 8;
byteIdx++;
}
this.Log(LogLevel.Debug, "Received response 0x{0:X} from the device", receivedWord);

if(!receiveDataMask.Value && dataMatcher.MatchAndPush(receiveFifo, receivedWord, byteIdx * 8, rxDataMatchOnly.Value))
if(!receiveDataMask.Value && dataMatcher.MatchAndPush(receiveFifo, receivedWord, byteCount * 8, rxDataMatchOnly.Value))
{
dataMatch.Value = true;
}
Expand Down Expand Up @@ -567,6 +580,7 @@ private void UpdateTransmitter(TCFifoEntry transmitEntry = null)
private IValueRegisterField rxWatermark;
private IFlagRegisterField continuingCommand;
private IFlagRegisterField continuousTransfer;
private IFlagRegisterField lsbFirst;
private IFlagRegisterField circularFifoEnabled;

private IFlagRegisterField receiveDataInterruptEnable;
Expand Down Expand Up @@ -596,6 +610,8 @@ private class TCFifoCmd : TCFifoEntry
public bool ContinuingCommand { get; set; }

public bool ByteSwap { get; set; }

public bool LsbFirst { get; set; }
}

private class TCFifoData : TCFifoEntry
Expand Down