onintr.htm

mips架构的bootloader,99左右的版本 但源代码现在没人更新了

<title>The onintr Library Function</title>
<h1 align=center>The onintr Library Function</h1>

<!--INDEX "Installing assembly language exception handlers" -->
<!--INDEX onintr -->

</dl><h2>NAME</h2><dl><dd>
     onintr - connect exception handler

</dl><h2>SYNOPSIS</h2><dl><dd>
<pre>
onintr (EXCCODE,handler)
</pre>

</dl><h2>DESCRIPTION</h2><dl><dd>
     onintr connects an assembly language execption handler to  a
     selected  EXCCODE  in  the CAUSE register, refer the LR33000
     for a list of EXCCODE values. This function is only available for
	  programs running under PMON.<p>

     When control is passed to the handler, the first element  of
     the  array,  whose  address  was  passed during the onintr()
     call, will contain  a  pointer  to  another  similar  array.
     Therefore,  if  the  handler decides that it doesn't want to
     handle this exception after all, it can pass control to  the
     next exception handler in the list.<p>


</dl><h2>EXAMPLE</h2><dl><dd>
<pre>
  typedef int iFunc();
  int hwint();
  iFunc *dat1[] = {0,hwint};

  main()
  {
  onintr(0,dat1);
  ....
  }

       .globl hwint
       .ent hwint
       .set noat
       .set noreorder
  hwint:
       # ignore non INT0 exceptions
       mfc0 k0,C0_CAUSE
       nop
       .set reorder
       sll  k0,21          # move INT0 to MSB
       bltz k0,1f          # branch if MSB set

       # if not, return to PMON
       la   k0,dat1
       lw   k0,(k0)
       lw   k0,4(k0)
       j    k0   # return to PMON

1:        .....
       User's handler
       .....

       # return to interrupted program
       .set noreorder
       mfc0 k0,C0_EPC
       nop
       j    k0
       rfe
       .set reorder
       .set at
       .end hwint
</pre>

For a complete example, see <a href="../../examples/pmon/onintr.c">onintr.c</a>
and <a href="../../examples/pmon/tisr.s">tisr.s</a>.<p>

</dl><p><hr>
<b>Navigation:</b> 
<a href="../index.htm">Document Home</a> | 
<a href="../doctoc.htm">Document Contents</a> | 
<a href="../docindex.htm">Document Index</a> <p>