X-Git-Url: https://oss.titaniummirror.com/gitweb/?p=tinyos-2.x.git;a=blobdiff_plain;f=tos%2Fchips%2Fcc2420%2Ftransmit%2FCC2420TransmitP.nc;h=a8367e54c99f0342df952fd65fda1dc59baf2e5c;hp=1b6cd48f5e0b5dd0b816d2db0c192e17c262fd2d;hb=aa7578fd1472c62c1d22d0801fe0f55b36093bdf;hpb=c3864fde9bec0c02c0c6b4221ddde0801a82c980

diff --git a/tos/chips/cc2420/transmit/CC2420TransmitP.nc b/tos/chips/cc2420/transmit/CC2420TransmitP.nc
index 1b6cd48f..a8367e54 100644
--- a/tos/chips/cc2420/transmit/CC2420TransmitP.nc
+++ b/tos/chips/cc2420/transmit/CC2420TransmitP.nc
@@ -236,12 +236,10 @@ implementation {
   }
   
   
-  inline uint32_t time16to32(uint16_t time, uint32_t recent_time)
+  inline uint32_t getTime32(uint16_t time)
   {
-    if ((recent_time&0xFFFF)<time)
-      return ((recent_time-0x10000UL)&0xFFFF0000UL)|time;
-    else
-      return (recent_time&0xFFFF0000UL)|time;
+    uint32_t recent_time=call BackoffTimer.getNow();
+    return recent_time + (int16_t)(time - recent_time);
   }
 
   /**
@@ -258,23 +256,30 @@ implementation {
    * would have picked up and executed had our microcontroller been fast enough.
    */
   async event void CaptureSFD.captured( uint16_t time ) {
-    uint32_t time32 = time16to32(time, call BackoffTimer.getNow());
+    uint32_t time32;
+    uint8_t sfd_state = 0;
     atomic {
+      time32 = getTime32(time);
       switch( m_state ) {
         
       case S_SFD:
         m_state = S_EFD;
         sfdHigh = TRUE;
+        // in case we got stuck in the receive SFD interrupts, we can reset
+        // the state here since we know that we are not receiving anymore
+        m_receiving = FALSE;
         call CaptureSFD.captureFallingEdge();
         call PacketTimeStamp.set(m_msg, time32);
         if (call PacketTimeSyncOffset.isSet(m_msg)) {
-           nx_uint8_t *taddr = m_msg->data + (call PacketTimeSyncOffset.get(m_msg) - sizeof(cc2420_header_t));
-           timesync_radio_t *timesync = (timesync_radio_t*)taddr;
+           uint8_t absOffset = sizeof(message_header_t)-sizeof(cc2420_header_t)+call PacketTimeSyncOffset.get(m_msg);
+           timesync_radio_t *timesync = (timesync_radio_t *)((nx_uint8_t*)m_msg+absOffset);
            // set timesync event time as the offset between the event time and the SFD interrupt time (TEP  133)
            *timesync  -= time32;
            call CSN.clr();
-           call TXFIFO_RAM.write( call PacketTimeSyncOffset.get(m_msg), (uint8_t*)timesync, sizeof(timesync_radio_t) );
+           call TXFIFO_RAM.write( absOffset, (uint8_t*)timesync, sizeof(timesync_radio_t) );
            call CSN.set();
+           //restoring the event time to the original value
+           *timesync  += time32;
         }
 
         if ( (call CC2420PacketBody.getHeader( m_msg ))->fcf & ( 1 << IEEE154_FCF_ACK_REQ ) ) {
@@ -284,16 +289,11 @@ implementation {
         releaseSpiResource();
         call BackoffTimer.stop();
 
-        
-        if ( ( ( (call CC2420PacketBody.getHeader( m_msg ))->fcf >> IEEE154_FCF_FRAME_TYPE ) & 7 ) == IEEE154_TYPE_DATA ) {
-          call PacketTimeStamp.set(m_msg, time32);
-        }
-        
         if ( call SFD.get() ) {
           break;
         }
         /** Fall Through because the next interrupt was already received */
-        
+
       case S_EFD:
         sfdHigh = FALSE;
         call CaptureSFD.captureRisingEdge();
@@ -311,9 +311,12 @@ implementation {
         /** Fall Through because the next interrupt was already received */
         
       default:
-        if ( !m_receiving ) {
+        /* this is the SFD for received messages */
+        if ( !m_receiving && sfdHigh == FALSE ) {
           sfdHigh = TRUE;
           call CaptureSFD.captureFallingEdge();
+          // safe the SFD pin status for later use
+          sfd_state = call SFD.get();
           call CC2420Receive.sfd( time32 );
           m_receiving = TRUE;
           m_prev_time = time;
@@ -321,18 +324,29 @@ implementation {
             // wait for the next interrupt before moving on
             return;
           }
+          // if SFD.get() = 0, then an other interrupt happened since we
+          // reconfigured CaptureSFD! Fall through
         }
         
-        sfdHigh = FALSE;
-        call CaptureSFD.captureRisingEdge();
-        m_receiving = FALSE;
-        if ( time - m_prev_time < 10 ) {
-          call CC2420Receive.sfd_dropped();
-	  if (m_msg)
-	    call PacketTimeStamp.clear(m_msg);
+        if ( sfdHigh == TRUE ) {
+          sfdHigh = FALSE;
+          call CaptureSFD.captureRisingEdge();
+          m_receiving = FALSE;
+          /* if sfd_state is 1, then we fell through, but at the time of
+           * saving the time stamp the SFD was still high. Thus, the timestamp
+           * is valid.
+           * if the sfd_state is 0, then either we fell through and SFD
+           * was low while we safed the time stamp, or we didn't fall through.
+           * Thus, we check for the time between the two interrupts.
+           * FIXME: Why 10 tics? Seams like some magic number...
+           */
+          if ((sfd_state == 0) && (time - m_prev_time < 10) ) {
+            call CC2420Receive.sfd_dropped();
+            if (m_msg)
+              call PacketTimeStamp.clear(m_msg);
+          }
+          break;
         }
-        break;
-      
       }
     }
   }