voip.c

基于实时嵌入式系统的voip系统（real time embeded system）。主要难点在实时处理语音信号。语音信号基于其自身特点

*   Function - startVOIP
*   Parameters - machineNumber - Set to 1 for machine that has server1IP
*      and set to 2 for machine that has server2IP.  This is just used
*      to configure the UDP server and client so that it knows
*      where it is sending messages to (i.e. the other machine).
*   Returns - void
*   Purpose - This is the main function to get everything going.
*      Configures the system, starts tasks, starts UDP stuff,
*      brings up audio card.
/**************************************************************************/
void startVOIP( int machineNumber )
{
    /* To ensure that taskDelay(1) is 1ms delay */
    sysClkRateSet(1000);

   /* set 8 bit mono by default */
   current_mode = 1;

   /*generate the rc4 key once*/
   rc4_init(&perm_key,&rc4_key_data,RC4_KEY_DATA_LEN);

   /*create semaphores*/
   SEM_RECEIVED = semBCreate(SEM_Q_FIFO,SEM_EMPTY);
   SEM_OK_TRANSMIT = semBCreate(SEM_Q_FIFO,SEM_EMPTY);
   SEM_ENCRYPT = semBCreate(SEM_Q_FIFO,SEM_EMPTY);
   SEM_DECRYPTED = semBCreate(SEM_Q_FIFO,SEM_EMPTY);

   /*start UDP server*/
   taskSpawn("udpServer", 5, 0, 4000, udpServer, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

	g_machine_number = machineNumber;
   /*set transmit to ip so that we know who we are sending packets to*/
   if( machineNumber == 1 )
   {
       transmitToIp = server2IP;
   }
   else
   {
      transmitToIp = server1IP;
   }

   taskDelay(5000);

   /*setup our client*/
   createUdpClient(transmitToIp);

   /*start up sound card*/
   startCS4281();

   /*start encrypt task*/
   taskSpawn("encryptionTask", 4, 0, 4000, encryptionTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start decrypt task*/
   taskSpawn("decryptionTask", 4, 0, 4000, decryptionTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start record task*/
   taskSpawn("getRecordBufferTask", 5, 0, 4000, getRecordBufferTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start transmit task*/
   taskSpawn("transmitTask", 5, 0, 4000, transmitTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start play task*/
   taskSpawn("setPlayBufferTask", 5, 0, 4000, setPlayBufferTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
}

/**************************************************************************
*   Function - stopVOIP
*   Parameters - none
*   Returns - void
*   Purpose - This function stops the DAC and ADC.  It shuts down the
*      tasks and closes the udp client connection.  The rest of the audio
*      card is still running and configured so that it start doing its
*      job again without configuration changes needed.  Call resumeVOIP
*      to start VOIP up again after this has been called.  Do not call
*      startVOIP again because that would try to configure a card that
*      has already been configured.
/**************************************************************************/
void stopVOIP()
{
   /*stop DAC and ADC*/
   stop_dac();

   /*shutdown tasks*/
   enable_transmit = 0;
   enable_play = 0;
   enable_record = 0;
   enable_encryption_task=0;
   enable_decryption_task=0;

   /*close udp client connection*/
   closeUdpClient();
}

/**************************************************************************
*   Function - resumeVOIP
*   Parameters - none
*   Returns - void
*   Purpose - This resumes VOIP after stopVOIP has been called.
*      It starts the DAC and ADC, creates a upd client again and
*      starts up the tasks.
/**************************************************************************/
void resumeVOIP()
{
   /*set task loop variables back so the tasks will run*/
   enable_transmit = 1;
   enable_play = 1;
   enable_record = 1;
   enable_encryption_task=1;
   enable_decryption_task=1;

   /*start DAC and ADC*/
   start_dac();

   /*create udp client connection*/
   createUdpClient(transmitToIp);

   /*start encrypt task*/
   taskSpawn("encryptionTask", 5, 0, 4000, encryptionTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start decrypt task*/
   taskSpawn("decryptionTask", 5, 0, 4000, decryptionTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start record task*/
   taskSpawn("getRecordBufferTask", 5, 0, 4000, getRecordBufferTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start transmit task*/
   taskSpawn("transmitTask", 5, 0, 4000, transmitTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

   /*start play task*/
   taskSpawn("setPlayBufferTask", 5, 0, 4000, setPlayBufferTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
}

/**************************************************************************
*   Function - switchMode
*   Parameters - int mode - The mode to switch this machine to.
*      1 = 8-bit mono, 2 = 8-bit stereo, 3 = 16-bit stereo
*   Returns - void
*   Purpose - Switch audio modes.  This function can be called at anytime
*      on either machine.  It will change the mode of this machine and
*      send a message to the other machine so it will also switch modes.
/**************************************************************************/
void switchMode(int mode)
{
   /*send a request to other machine to switch modes*/
   transmitRequest.request_type = 1;
   transmitRequest.mode = mode;
   udpSendRequest();

   /*stop voip on this machine (to minimize noise when switch modes*/
   stopVOIP();

   /*set global to new mode*/
   current_mode = mode;

   /*re-configure DMAs, DAC and ADC to handle new mode*/
   audio_switchMode();

   /*send a request to other machine to start its ADC/DAC back up*/
   createUdpClient(transmitToIp);
   transmitRequest.request_type = 2;
   udpSendRequest();
   closeUdpClient();

   /*start VOIP up again*/
   resumeVOIP();
}

/**************************************************************************
*   Function - localSwitchMode
*   Parameters - int mode - The mode to switch this machine to.
*      1 = 8-bit mono, 2 = 8-bit stereo, 3 = 16-bit stereo
*   Returns - void
*   Purpose - This should never be called at a shell window.  It should
*      be considered a private function that is only called internally
*      to the system.  It switches the mode on the local machine only,
*      so it is called by the udpServer when a message is received
*      telling it to switch modes.
/**************************************************************************/
void localSwitchMode(int mode) /* only switches mode locally, not on other machine*/
{
   stopVOIP();
   current_mode = mode;
   audio_switchMode();
}

/**************************************************************************
*   Function - setVolume
*   Parameters - int value - Number between 0 and 10.
*   Returns - void
*   Purpose - This is supposed to change the volume, but doesn't work.
/**************************************************************************/
void setVolume(int value)
{
   UINT32 new_value = 0;

   switch(value)
   {
   case 0:
      new_value = 0x13F3F;
   case 1:
      new_value = 0x3A3A;
   case 2:
      new_value = 0x3636;
   case 3:
      new_value = 0x3232;
   case 4:
      new_value = 0x2E2E;
   case 5:
      new_value = 0x2A2A;
   case 6:
      new_value = 0x2626;
   case 7:
      new_value = 0x2222;
   case 8:
      new_value = 0x1E1E;
   case 9:
      new_value = 0x0D0D;
   case 10:
      new_value = 0x0;
   default:
      new_value = 0x0;
   }

   cs4281_write_ac97(BA0_AC97_MASTER_VOLUME, new_value);

}

/**************************************************************************
*   Function - testrc4
*   Parameters - none
*   Returns - void
*   Purpose - Function used to test the rc4 encryption.
/**************************************************************************/
int testrc4()
{
   unsigned char key[8] = {23,82,107,6,35,78,88,7};
	char buf[8];
   rc4_key test;
   rc4_key perm;

	buf[0] = 'H';
   buf[1] = 'e';
   buf[2] = 'r';
  	buf[3] = 'e';
   buf[4] = ' ';
   buf[5] = 'w';
  	buf[6] = 'e';
   buf[7] = '\0';

	printf("before value: %s \n",buf);
   rc4_init(&test,&key,8);
	printf("x: %i, y: %i, state: %s\n",test.x,test.y,test.state);

   perm.x = test.x;
   perm.y = test.y;
	memmove(perm.state,test.state, 256);
	printf("perm x: %i, y: %i, state: %s\n",perm.x,perm.y,perm.state);

   rc4_crypt(&test,buf,buf,8);
	printf("test a x: %i, y: %i, state: %s\n",test.x,test.y,test.state);
   printf("encrypted value: %s \n",buf);
   test.x = perm.x;
   test.y = perm.y;
	memmove(test.state,perm.state, 256);
	printf("test b x: %i, y: %i, state: %s\n",test.x,test.y,test.state);
   rc4_crypt(&test,buf,buf,8);
   printf("decrypted value: %s \n",buf);
}