apply optimizations to nRF24 radio handler by @khamann

lib/Radio/PL1167_nRF24.cpp

@@ -1,126 +1,85 @@
 /*
  * PL1167_nRF24.cpp
  *
+ * Adapted from work by henryk:
+ *  https://github.com/henryk/openmili
  *  Created on: 29 May 2015
  *      Author: henryk
+ * Optimizations by khamann:
+ *  https://github.com/khmann/esp8266_milight_hub/blob/e3600cef75b102ff3be51a7afdb55ab7460fe712/lib/MiLight/PL1167_nRF24.cpp
+ *
  */
 
 #include "PL1167_nRF24.h"
 
 static uint16_t calc_crc(uint8_t *data, size_t data_length);
 static uint8_t reverse_bits(uint8_t data);
-static void demangle_packet(uint8_t *in, uint8_t *out) ;
 
 PL1167_nRF24::PL1167_nRF24(RF24 &radio)
   : _radio(radio)
 { }
 
-static const uint8_t pipe[] = {0xd1, 0x28, 0x5e, 0x55, 0x55};
-
 int PL1167_nRF24::open()
 {
   _radio.begin();
+  _radio.setAutoAck(false);
+  _radio.setPALevel(RF24_PA_MAX);
+  _radio.setDataRate(RF24_1MBPS);
+  _radio.disableCRC();
+
+  _syncwordLength = 5;
+  _radio.setAddressWidth(_syncwordLength);
+
   return recalc_parameters();
 }
 
 int PL1167_nRF24::recalc_parameters()
 {
-  int nrf_address_length = _preambleLength - 1 + _syncwordLength;
-  int address_overflow = 0;
-  if (nrf_address_length > 5) {
-    address_overflow = nrf_address_length - 5;
-    nrf_address_length = 5;
-  }
-  int packet_length = address_overflow + ( (_trailerLength + 7) / 8) + _maxPacketLength;
-  if (_crc) {
-    packet_length += 2;
-  }
-
-  if (packet_length > sizeof(_packet) || nrf_address_length < 3) {
-    return -1;
-  }
+  int packet_length = _maxPacketLength + 2;
+  int nrf_address_pos = _syncwordLength;
 
-  uint8_t preamble = 0;
   if (_syncword0 & 0x01) {
-    preamble = 0x55;
+    _nrf_pipe[ --nrf_address_pos ] = reverse_bits( ( (_syncword0 << 4) & 0xf0 ) + 0x05 );
   } else {
-    preamble = 0xAA;
-  }
-
-  int nrf_address_pos = nrf_address_length;
-  for (int i = 0; i < _preambleLength - 1; i++) {
-    _nrf_pipe[ --nrf_address_pos ] = reverse_bits(preamble);
-  }
-
-  if (nrf_address_pos) {
-    _nrf_pipe[ --nrf_address_pos ] = reverse_bits(_syncword0 & 0xff);
-  }
-  if (nrf_address_pos) {
-    _nrf_pipe[ --nrf_address_pos ] = reverse_bits( (_syncword0 >> 8) & 0xff);
-  }
-
-  if (_syncwordLength == 4) {
-    if (nrf_address_pos) {
-      _nrf_pipe[ --nrf_address_pos ] = reverse_bits(_syncword3 & 0xff);
-    }
-    if (nrf_address_pos) {
-      _nrf_pipe[ --nrf_address_pos ] = reverse_bits( (_syncword3 >> 8) & 0xff);
-    }
+    _nrf_pipe[ --nrf_address_pos ] = reverse_bits( ( (_syncword0 << 4) & 0xf0 ) + 0x0a );
   }
+  _nrf_pipe[ --nrf_address_pos ] = reverse_bits( (_syncword0 >> 4) & 0xff);
+  _nrf_pipe[ --nrf_address_pos ] = reverse_bits( ( (_syncword0 >> 12) & 0x0f ) + ( (_syncword3 << 4) & 0xf0) );
+  _nrf_pipe[ --nrf_address_pos ] = reverse_bits( (_syncword3 >> 4) & 0xff);
+  _nrf_pipe[ --nrf_address_pos ] = reverse_bits( ( (_syncword3 >> 12) & 0x0f ) + 0x50 );	// kh: spi says trailer is always "5" ?
 
   _receive_length = packet_length;
-  _preamble = preamble;
 
-  _nrf_pipe_length = nrf_address_length;
-  _radio.setAddressWidth(_nrf_pipe_length);
   _radio.openWritingPipe(_nrf_pipe);
   _radio.openReadingPipe(1, _nrf_pipe);
 
   _radio.setChannel(2 + _channel);
 
-
   _radio.setPayloadSize( packet_length );
-  _radio.setAutoAck(false);
-  _radio.setPALevel(RF24_PA_MAX);
-  _radio.setDataRate(RF24_1MBPS);
-  _radio.disableCRC();
-
   return 0;
 }
 
 
 int PL1167_nRF24::setPreambleLength(uint8_t preambleLength)
-{
-  if (preambleLength > 8) {
-    return -1;
-  }
-  _preambleLength = preambleLength;
-  return recalc_parameters();
-}
+{ return 0; }
+/* kh- no thanks, I'll take care of this */
 
 
 int PL1167_nRF24::setSyncword(uint16_t syncword0, uint16_t syncword3)
 {
-  _syncwordLength = 4;
+  _syncwordLength = 5;
   _syncword0 = syncword0;
   _syncword3 = syncword3;
   return recalc_parameters();
 }
 
 int PL1167_nRF24::setTrailerLength(uint8_t trailerLength)
-{
-  if (trailerLength < 4) {
-    return -1;
-  }
-  if (trailerLength > 18) {
-    return -1;
-  }
-  if (trailerLength & 0x01) {
-    return -1;
-  }
-  _trailerLength = trailerLength;
-  return recalc_parameters();
-}
+{ return 0; }
+/* kh- no thanks, I'll take care of that.
+   One could argue there is potential value to "defining" the trailer - such that
+   we can use those "values" for internal (repeateR?) functions since they are
+   ignored by the real PL1167..  But there is no value in _this_ implementation...
+*/
 
 int PL1167_nRF24::setCRC(bool crc)
 {
@@ -202,69 +161,18 @@ int PL1167_nRF24::transmit(uint8_t channel)
 
   _radio.stopListening();
   uint8_t tmp[sizeof(_packet)];
+  int outp=0;
 
-  uint8_t trailer = (_packet[0] & 1) ? 0x55 : 0xAA;  // NOTE: This is a guess, it might also be based upon the last
-  // syncword bit, or fixed
-  int outp = 0;
-
-  for (; outp < _receive_length; outp++) {
-    uint8_t outbyte = 0;
-
-    if (outp + 1 + _nrf_pipe_length < _preambleLength) {
-      outbyte = _preamble;
-    } else if (outp + 1 + _nrf_pipe_length < _preambleLength + _syncwordLength) {
-      int syncp = outp - _preambleLength + 1 + _nrf_pipe_length;
-      switch (syncp) {
-        case 0:
-          outbyte = _syncword0 & 0xFF;
-          break;
-        case 1:
-          outbyte = (_syncword0 >> 8) & 0xFF;
-          break;
-        case 2:
-          outbyte = _syncword3 & 0xFF;
-          break;
-        case 3:
-          outbyte = (_syncword3 >> 8) & 0xFF;
-          break;
-      }
-    } else if (outp + 1 + _nrf_pipe_length < _preambleLength + _syncwordLength + (_trailerLength / 8) ) {
-      outbyte = trailer;
-    } else {
-      break;
-    }
-
-    tmp[outp] = reverse_bits(outbyte);
-  }
-
-  int buffer_fill;
-  bool last_round = false;
-  uint16_t buffer = 0;
   uint16_t crc;
   if (_crc) {
     crc = calc_crc(_packet, _packet_length);
   }
 
-  buffer = trailer >> (8 - (_trailerLength % 8));
-  buffer_fill = _trailerLength % 8;
   for (int inp = 0; inp < _packet_length + (_crc ? 2 : 0) + 1; inp++) {
     if (inp < _packet_length) {
-      buffer |= _packet[inp] << buffer_fill;
-      buffer_fill += 8;
-    } else if (_crc && inp < _packet_length + 2) {
-      buffer |= ((crc >>  ( (inp - _packet_length) * 8)) & 0xff) << buffer_fill;
-      buffer_fill += 8;
-    } else {
-      last_round = true;
-    }
-
-    while (buffer_fill > (last_round ? 0 : 8)) {
-      if (outp >= sizeof(tmp)) {
-        return -1;
-      }
-      tmp[outp++] = reverse_bits(buffer & 0xff);
-      buffer >>= 8;
-      buffer_fill -= 8;
+      tmp[outp++] = reverse_bits(_packet[inp]);}
+    else if (_crc && inp < _packet_length + 2) {
+      tmp[outp++] = reverse_bits((crc >> ( (inp - _packet_length) * 8)) & 0xff);
     }
   }
 
@@ -285,9 +193,6 @@ int PL1167_nRF24::internal_receive()
   // HACK HACK HACK: Reset radio
   open();
 
-  uint8_t shift_amount = _trailerLength % 8;
-  uint16_t buffer = 0;
-
 #ifdef DEBUG_PRINTF
   printf("Packet received: ");
   for (int i = 0; i < _receive_length; i++) {
@@ -297,53 +202,7 @@ int PL1167_nRF24::internal_receive()
 #endif
 
   for (int inp = 0; inp < _receive_length; inp++) {
-    uint8_t inbyte = reverse_bits(tmp[inp]);
-    buffer = (buffer >> 8) | (inbyte << 8);
-
-    if (inp + 1 + _nrf_pipe_length < _preambleLength) {
-      if (inbyte != _preamble) {
-#ifdef DEBUG_PRINTF
-        printf("Preamble fail (%i: %02X)\n", inp, inbyte);
-#endif
-        return 0;
-      }
-    } else if (inp + 1 + _nrf_pipe_length < _preambleLength + _syncwordLength) {
-      int syncp = inp - _preambleLength + 1 + _nrf_pipe_length;
-      switch (syncp) {
-        case 0:
-          if (inbyte != _syncword0 & 0xFF) {
-#ifdef DEBUG_PRINTF
-            printf("Sync 0l fail (%i: %02X)\n", inp, inbyte);
-#endif
-            return 0;
-          } break;
-        case 1:
-          if (inbyte != (_syncword0 >> 8) & 0xFF) {
-#ifdef DEBUG_PRINTF
-            printf("Sync 0h fail (%i: %02X)\n", inp, inbyte);
-#endif
-            return 0;
-          } break;
-        case 2:
-          if ((_syncwordLength == 4) && (inbyte != _syncword3 & 0xFF)) {
-#ifdef DEBUG_PRINTF
-            printf("Sync 3l fail (%i: %02X)\n", inp, inbyte);
-#endif
-            return 0;
-          } break;
-        case 3:
-          if ((_syncwordLength == 4) && (inbyte != (_syncword3 >> 8) & 0xFF)) {
-#ifdef DEBUG_PRINTF
-            printf("Sync 3h fail (%i: %02X)\n", inp, inbyte);
-#endif
-            return 0;
-          } break;
-      }
-    } else if (inp + 1 + _nrf_pipe_length < _preambleLength + _syncwordLength + ((_trailerLength + 7) / 8) ) {
-
-    } else {
-      tmp[outp++] = buffer >> shift_amount;
-    }
+      tmp[outp++] = reverse_bits(tmp[inp]);
   }