Error Function

Various errors can cause the system to crash when the system is running. For critical errors, the system calls the system error function sys_error(). This makes is possible to catch the exception and possibly recover from it.

The system can, for example, run out of memory or fail to allocate the TCP socket. These are usually an indication that the system configuration is wrong and needs to be corrected. The error function alerts the developer as to what requires changing.

The parameter code holds the error code of the exception. This can have the following values:

Error Code	Type of Error	Description
ERR_MEM_ALLOC	Out of memory	This is normally the case when the memory pool size is too small. You must increase the size of the memory pool in the configuration.
ERR_MEM_FREE	Invalid memory block release	Possible reason is that the link pointers were overwritten by the user. This can happen when the user application has written buffer data out of boundaries of the allocated memory block.
ERR_MEM_CORRUPT	Link pointer corrupted	The system memory link is corrupted and points to an odd address. Resuming the program execution would cause the Hard Fault or B-Class Trap with Illegal Word Operand Access. Possible reason is writing buffer data out of boundaries of the allocated memory block.
ERR_MEM_LOCK	Memory management function re-entered	The system alloc or free memory function was interrupted by a task or interrupt and then called again. This would corrupt memory handling. Possible reason is wrong usage of TCPnet functions from different tasks. Only BSD socket functions are thread safe, all other functions are not.
ERR_UDP_ALLOC	No free UDP Sockets	The system has run out of UDP sockets. You must increase the number of available UDP sockets in the configuration.
ERR_TCP_ALLOC	No free TCP Sockets	The system has run out of TCP sockets. You must increase the number of available TCP sockets in the configuration.
ERR_TCP_STATE	Undefined State	TCP socket is in an undefined state. This can happen when the system memory is accidentally overwritten by the user application.

This is an example of the error function which can be customized. This function currently does nothing but stop the TCPnet system by running in an endless loop.

void sys_error (ERROR_CODE code) {
  /* This function is called when a fatal error is encountered. The normal */
  /* program execution is not possible anymore. Add your critical error    */
  /* handler code here.                                                    */

  switch (code) {
    case ERR_MEM_ALLOC:
      /* Out of memory. */
      break;

    case ERR_MEM_FREE:
      /* Trying to release non existing memory block. */
      break;

    case ERR_MEM_CORRUPT:
      /* Memory Link pointer is Corrupted. */
      /* More data written than the size of allocated mem block. */
      break;

    case ERR_MEM_LOCK:
      /* Locked Memory management function (alloc/free) re-entered. */
      /* RTX multithread protection malfunctioning, not implemented */
      /* or interrupt disable is not functioning correctly. */
      break;

    case ERR_UDP_ALLOC_SOCKET:
      /* Out of UDP Sockets. */
      break;

    case ERR_TCP_ALLOC_SOCKET:
      /* Out of TCP Sockets. */
      break;

    case ERR_TCP_STATE_UNDEFINED:
      /* TCP State machine in undefined state. */
      break;
  }

  /* End-less loop */
  while (1);
}

The ERR_MEM_LOCK error was added in RLARM version 4.53

Error Function

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