extern bool Nrf24l::dataReady()
// Checks if data is available for reading
{
// See note in getData() function - just checking RX_DR isn't good enough
uint8_t status = getStatus();
// We can short circuit on RX_DR, but if it's not set, we still need
// to check the FIFO for any pending packets
if ( status & (1 << RX_DR) ) return 1;
return !rxFifoEmpty();
}
extern bool Nrf24l::dataReady()
// Checks if data is available for reading
// 检测是否有可读的数据
{
// See note in getData() function - just checking RX_DR isn't good enough
// 查看 getData() 函数说明，
// 只检查 RX_DR(接收数据中断，当接收到有效数据后置一) 并不是好办法。
uint8_t status = getStatus();
// We can short circuit on RX_DR, but if it's not set, we still need
// to check the FIFO for any pending packets
// 可以快速的检测 RX_DR ，但是如果没有检测到，还得检测FIFO是否空。
if ( status & (1 << RX_DR) ) return 1;
return !rxFifoEmpty();
}
HRESULT BtI2cControllerClass::_performContiguousTransfers(I2cTransferClass* & pXfr)
{
ULONGLONG startWaitTicks = 0;
ULONGLONG currentTicks = 0;
I2cTransferClass* cmdXfr = nullptr;
I2cTransferClass* readXfr = nullptr;
PUCHAR readPtr = nullptr;
HRESULT hr = S_OK;
BOOL restart = FALSE;
ULONG cmdDat;
LONG cmdsOutstanding = 0;
LONG readsOutstanding = 0;
UCHAR outByte;
UCHAR inByte;
if (pXfr == nullptr)
{
hr = DMAP_E_DMAP_INTERNAL_ERROR;
}
if (SUCCEEDED(hr))
{
// Calculate the command and read counts for the current sequence of
// contiguous transfers in this transaction.
hr = calculateCurrentCounts(pXfr, cmdsOutstanding, readsOutstanding);
}
// For each transfer in this section of the transaction:
cmdXfr = pXfr;
while (SUCCEEDED(hr) && (cmdsOutstanding > 0) && (cmdXfr != nullptr))
{
// If this is the first read transfer in this sequence of transfers:
if ((readXfr == nullptr) && cmdXfr->transferIsRead())
{
// Indicate this is the transfer to read into.
readXfr = cmdXfr;
readXfr->resetRead();
readPtr = readXfr->getNextReadLocation();
}
// Prepare to access the cmd buffer.
cmdXfr->resetCmd();
// Signal a pre-restart if this transfer is marked for one.
if (cmdXfr->preResart())
{
restart = TRUE;
}
// For each byte in the transfer:
while (SUCCEEDED(hr) && (cmdXfr->getNextCmd(outByte)))
{
// Wait for at least one empty space in the TX FIFO.
while (txFifoFull());
// Issue the command.
if (cmdXfr->transferIsRead())
{
cmdDat = 0x100; // Build read command (data is ignored)
}
else
{
cmdDat = outByte; // Build write command with data byte
}
// If restart has been requested, signal a pre-RESTART.
if (restart)
{
cmdDat = cmdDat | (1 << 10);
restart = FALSE; // Only want to RESTART on first command of transfer
}
// If this is the last command before the end of the transaction or
// before a callback, signal a STOP.
if (cmdsOutstanding == 1)
{
cmdDat = cmdDat | (1 << 9);
}
// Issue the command.
m_registers->IC_DATA_CMD.ALL_BITS = cmdDat;
cmdsOutstanding--;
hr = _handleErrors();
// Pull any available bytes out of the receive FIFO.
while (SUCCEEDED(hr) && rxFifoNotEmtpy())
{
// Read a byte from the I2C Controller.
inByte = readByte();
readsOutstanding--;
// Store the byte if we have a place for it.
if (readPtr != nullptr)
{
*readPtr = inByte;
// Figure out where the next byte should go.
readPtr = readXfr->getNextReadLocation();
while ((readPtr == nullptr) && (readXfr->getNextTransfer() != nullptr))
{
readXfr = readXfr->getNextTransfer();
readXfr->resetRead();
readPtr = readXfr->getNextReadLocation();
}
}
}
}
if (SUCCEEDED(hr))
{
cmdXfr = cmdXfr->getNextTransfer();
}
}
// Complete any outstanding reads and wait for the TX FIFO to empty.
startWaitTicks = GetTickCount64();
currentTicks = startWaitTicks;
while (SUCCEEDED(hr) && ((readsOutstanding > 0) || !txFifoEmpty()) && !errorOccurred())
{
// Pull any available bytes out of the receive FIFO.
while (rxFifoNotEmtpy())
{
// Read a byte from the I2C Controller.
inByte = readByte();
readsOutstanding--;
// Store the byte if we have a place for it.
if (readPtr != nullptr)
{
*readPtr = inByte;
// Figure out where the next byte should go.
readPtr = readXfr->getNextReadLocation();
while ((readPtr == nullptr) && (readXfr->getNextTransfer() != nullptr))
{
readXfr = readXfr->getNextTransfer();
readXfr->resetRead();
readPtr = readXfr->getNextReadLocation();
}
}
}
// Wait up to to 100 milliseconds for transfers to happen.
if (readsOutstanding > 0)
{
currentTicks = GetTickCount64();
if (((currentTicks - startWaitTicks) > 100) && rxFifoEmpty())
{
hr = DMAP_E_I2C_READ_INCOMPLETE;
}
}
}
// Determine if an error occured on this transaction.
if (SUCCEEDED(hr))
{
hr = _handleErrors();
}
// Pass the next transfer pointer back to the caller.
pXfr = cmdXfr;
// Record the read wait count for debugging purposes.
if ((currentTicks - startWaitTicks) > m_maxWaitTicks)
{
m_maxWaitTicks = (ULONG)(currentTicks - startWaitTicks);
}
if (SUCCEEDED(hr))
{
// Check for some catch-all errors.
if (cmdsOutstanding > 0)
{
hr = DMAP_E_I2C_OPERATION_INCOMPLETE;
}
else if (readsOutstanding < 0)
{
hr = DMAP_E_I2C_EXTRA_DATA_RECEIVED;
}
else if (cmdsOutstanding < 0)
{
hr = DMAP_E_DMAP_INTERNAL_ERROR;
}
}
return hr;
}