Message-Id:	<v03130300b185c83566a2@[128.155.2.168]>
In-Reply-To:	<Pine.SUN.3.91.980517140418.14173J-100000@is>
References:	<kaplan-1405981731120001 AT hokie DOT larc DOT nasa DOT gov>
Mime-Version:	1.0
Date:	Mon, 18 May 1998 07:21:55 -0400
To:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
From:	Joseph Kaplan <j DOT a DOT kaplan AT larc DOT nasa DOT gov>
Subject:	Re: hardware interrupts
Cc:	djgpp AT delorie DOT com

At 14:04 +0300 5/17/98, you wrote:

>On Thu, 14 May 1998, Joseph Kaplan wrote:
>
>>   _go32_dpmi_chain_protected_mode_interrupt_vector(
>>     interrupt_vector,
>>     &protected_receive_handler);
>
>Why do you need to chain?  Is there any other handler for this board
>anywhere on your machine?
>
No, but I was running out of options.  I have also just installed
a protected mode handler without the real mode handler.  The
real mode handler doesn't do anything.

>
>>   _go32_dpmi_get_real_mode_interrupt_vector(
>>     interrupt_vector,
>>     &real_previous_handler);
>
>Why do you need to install a real-mode handler?  In DPMI mode, all the
>hardware interrupts are automatically reflected to the protected-mode
>handler, so you don't need the real-mode one.
>
See above.

>> This is not working.
>
>``Not working''--how?  Please explain what happens when your program
>runs.
>
The program runs fine.  The problem is that when data arrives
at the board, it is supposed to set a status flag to true
and then signal an interrupt on IRQ 5.  This, in turn, should
force my interrupt handler to get called.  My interrupt handler
is not being called.  I have put a print statement in the
interrupt handler to show this.

>> What am I missing here?
>
>First, your code only installs the handler, but you didn't show the
>handler itself.  It might be that the problem is there.
>

Here is the relevant code.


//============================================================================
//* Method: CondorArinc429Impl::protectedInterruptHandler(...)
//* Handles interrupt for CondorArinc card
//============================================================================
void CondorArinc429Impl::protectedInterruptHandler(...)
{
  cout << "Interrupt Handler" << endl;
  determineReceiver();
  outportb(interrupt_control_port,interrupt_acknowledge);
}

//============================================================================
//* Method CondorArinc429Impl::determineReceiver()
//* Statically determines which receiver caused an interrupt,read that receiver
//============================================================================
void CondorArinc429Impl::determineReceiver()
/* statically determines which receiver caused the interrupt  */
{
  int status;

  // Read the Status word for receivers 1 and 2

  status = inportb(interrupt_set[RECEIVE_CHANNEL_1].read_status);
  if (status & STATUS_R1_FULL)
  {
    getInputData(RECEIVE_CHANNEL_1);
  }
  else if (status & STATUS_R2_FULL)
  {
    getInputData(RECEIVE_CHANNEL_2);
  }
  else
  {

    // Read the Status word for receivers 3 and 4

    status = inportb(interrupt_set[RECEIVE_CHANNEL_3].read_status);
    if  (status & STATUS_R3_FULL)
    {
      getInputData(RECEIVE_CHANNEL_3);
    }
    else if (status & STATUS_R4_FULL)
    {
      getInputData(RECEIVE_CHANNEL_4);
    }
    else
    {
      false_interrupts++;
    }
  }
}

//============================================================================
//* Method CondorArinc429Impl::getInputData(receive_channel channel)
//* Given a channel, reads data on that channel (done on an interrupt)
//============================================================================
void CondorArinc429Impl::getInputData(receive_channel channel)
{
  unsigned long data;
  unsigned char *arinc_word_pointer = (unsigned char*)&data;

  inportb(interrupt_set[channel].receiver_enable);
  inportb(interrupt_set[channel].read_least_sig_word);

  *arinc_word_pointer++ = inportb(interrupt_set[channel].read_low_byte);
  *arinc_word_pointer++ = inportb(interrupt_set[channel].read_high_byte);

  inportb(interrupt_set[channel].read_most_sig_word);

  *arinc_word_pointer++ = inportb(interrupt_set[channel].read_low_byte);
  *arinc_word_pointer++ = inportb(interrupt_set[channel].read_high_byte);

  inportb(interrupt_set[channel].receiver_disable);

  int toggle_status = interrupt_set[channel].toggle;
  interrupt_set[channel].receive_queue[toggle_status]->push(data);
}


>Second, the code and data of the handler need to be locked.
>
I didn't lock any of the code or the data because I am using
CWSDPR0 as my memory manager.  I thought that was only
necessary if you had a paging memory manager.

>Last but not least, I suggest to read section 18.9 of the DJGPP FAQ
>list, if you haven't done that already.
>
I did.  I believe now that my problem may be hardware related at
this point.  I am going to check the status of IRQ 5 on the bus
to insure that it is generating the interrupt.

Thanks for the advice.

Joe

-----------------------------------------------------------
| Joseph Kaplan            | NASA Langley Research Center |
| j DOT a DOT kaplan AT larc DOT nasa DOT gov | Simulation Systems Branch    |
| VOICE: 757-864-6491      | Simulation & Research        |
| FAX:   757-864-8338      | Aircraft Division            |
-----------------------------------------------------------

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