The horror... the horror...

// Add this transmitter to the pending data list, if it isn't already in it.
static void vAddToPendingList(TTRANSMITTER *pTX)
  {
  // Make sure we aren't already in the list... relying on a flag, urgh.
  if (!pTX->bPendingData)
    {
    // We're going on the end, so we don't point at anyone after us
    pTX->pNextPending=NULL;
    // Add us to the end of the list, if we have a pointer to the end
    if (pLastPending != NULL)
      {
      pLastPending->pNextPending = pTX;
      }
    // Regardless, this one is now the end.
    pLastPending = pTX;
    // Add us to the start of the list, if we don't have one
    if (pFirstPending == NULL)
      {
      pFirstPending = pTX;
      // If there wasn't a list the existing count must be zero, we'll inc it later.
      u32PendingTxCount = 0;
      }
    // Set the flag
    pTX->bPendingData = true;
    // And increment the pending count
    u32PendingTxCount++;
    }
  }

// Remove a transmitter from the pending list. Hopefully it's at the front.
static void vRemoveFromPendingList(TTRANSMITTER *pTX)
  {
  TTRANSMITTER *pTXInList;

  // Avoid duff pointers
  if (pTX == NULL)
    return;
  // Make sure it's actually in the list...
  if (pTX->bPendingData)
    {
    // So, we think we're in the list
    // Decrement the count
    if (u32PendingTxCount>0)
      u32PendingTxCount--;
    // Are we the first in the list?
    if (pFirstPending == pTX)
      {
      // It was the first, so the next becomes first
      pFirstPending = pTX->pNextPending;
      // Was it also the last?
      if (pLastPending == pTX)
        {
        // First and last, so clear the pLast
        pLastPending = NULL;
        // And we know there can't be any
        u32PendingTxCount=0;
        }
      }
    else
      {
      // Bugger, we're not the first in the list. So we need to chase down the list until we find this entry
      pTXInList = pFirstPending;
      // We know this first one cannot be us, we've checked for that.
      while (pTXInList != NULL)
        {
        // Are we the next one in the pending list after this one?
        if (pTXInList->pNextPending == pTX)
          {
          // Yes, so clip us out of the list
          pTXInList->pNextPending = pTX->pNextPending;
          // Now, we need to check if this makes this one the last one in the list and update pLast if it does
          if (pTXInList->pNextPending == NULL)
            pLastPending = pTXInList;
          // We can't appear in the list twice, so we're done...
          break;
          }
        // Look at the next pending transmitter
        pTXInList = pTXInList->pNextPending;
        }
      }
    }
  // Now, clear our list maintainence variables against future checking
  pTX->bPendingData = false;
  pTX->pNextPending = NULL;
  }