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Altera_Forum
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15 years ago

Message Q with Data Structure help

Good day. I am a little rusty on C so would like some basic help. I would like to define a structure to hold Character LCD data such as the text string, the position, and the style. I would like to use the structure to pass messages to the LCD display task which will then write to the LCD.

I have defined

typedef struct message{

char text[16];

int xpos;

int ypos;

enum { STEADY, BLINK } textstyle;

} LCDMessage

LCDMessage LCDMessages[10];

Now what is the proper method of initializing the Q for MicroC because all the examples show the void type for pointer. So I'm guessing I need to map an array of pointers to the data structures but not sure. Can someone please straighten me out and show me a simple example using a structure for messages. Is this possible?

Thanks

JT

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    I do it like this: 

    
# define L_CMD_BUFFER_SIZE       0x1000 // Only  Hexnumbers like 0x10, 0x20 ......
# define L_MSG_QUEUE_MASK        (L_CMD_BUFFER_SIZE - 1) 
      
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////
LCDMessage m_t_msg_buffer;
unsigned int  m_ui_message_write_pointer;
OS_EVENT *    m_message_queue;
......
void init_message_system
   (
   void
   )
   {
   m_ui_message_write_pointer = 0;
   if(!(m_message_queue = OSQCreate(&m_CommMsg, 
                                    L_CMD_BUFFER_SIZE)))
      {
      puts("OSQCreate() failed\r\n");
      return;
      }
   }
void send_message
   (
   const LCDMessage  * para_t_command
   )
   {
  # if OS_CRITICAL_METHOD == 3
      OS_CPU_SR cpu_sr;
  # endif
   OS_ENTER_CRITICAL();
   memcpy(&m_t_cmd_buffer, 
          para_t_command,
          sizeof(LCDMessage));
   OS_EXIT_CRITICAL();
   switch(OSQPost(m_message_queue,
                  (void *)&m_t_cmd_buffer))
      {
      case OS_NO_ERR:
         {
         break;   
         }   
      case OS_Q_FULL:
         {
         // error handling
         ....
         break;            
         }
      case OS_ERR_EVENT_TYPE:
         {
         // error handling
         ....
         break;
         }
      case OS_ERR_PEVENT_NULL:
         {
         // error handling
         ....
         break;
         }
      case OS_ERR_POST_NULL_PTR:
         {
         // error handling
          ....
          break;
          }
      default:
         {
         // error handling
          ....
          break;
          }
      }
   OS_ENTER_CRITICAL();
   m_ui_message_write_pointer = (m_ui_message_write_pointer + 1) & L_MSG_QUEUE_MASK;
   OS_EXIT_CRITICAL(); 
   }
bool get_message
   (
   LCDMessage   * para_ptr_command_buffer, 
   INT16U          para_ui_timeout
   )
   { 
   LCDMessage  * proc_ptr_command;
   INT8U           proc_os_error;
  # if OS_CRITICAL_METHOD == 3
      OS_CPU_SR cpu_sr;
  # endif
   
   proc_ptr_command = 
         (t_command_typ *)OSQPend(m_message_queue,
                                  para_ui_timeout,
                                  &proc_os_error);
   switch(proc_os_error)
      {
      case OS_NO_ERR:
         {
         OS_ENTER_CRITICAL();
         memcpy(para_ptr_command_buffer, 
                proc_ptr_command,
                sizeof(LCDMessage  ));
         OS_EXIT_CRITICAL(); 
         return(true); // msg received
         }   
      case OS_TIMEOUT:
         {
         return(false);
         }   
      case OS_ERR_EVENT_TYPE:
         {
         // error handling
         ...
         return(false);
         }   
      case OS_ERR_PEVENT_NULL:
         {
         // error handling
         ...
         return(false);
         }   
      case OS_ERR_PEND_ISR:
         {
         // error handling
         ...
         return(false);
         }   
     default:
         {
         // error handling
         ...
         return(false);
         }   
      }
   }
    I used C++ therefore the bool type

    karsten
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    OS_EVENT * some_queue;

    void* some_queue_tbl[16];

    some_queue = OSQCreate(&some_queue_tbl[0], 16);

    task1

    {

    OSQPost(some_queue, (void *)pointer_to_your_struct);

    }

    task2

    {

    your_struct_type * pointer_to_my_struct_type;

    pointer_to_my_struct_type = (your_struct_type *)OSQPend(some_que, 0, &err);

    }