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Abort some questions of arm interrupt

Note: This was originally posted on 20th June 2008 at http://forums.arm.com

I try to understand arm interrupt,there are some questions I don't know,
  1.   Why the nested interrupt has to switch out of irq mode to svc mode?  I think  it only pushes the r14_irq into the irq stack.
   2.    The basic difference between a reentrant interrupt handler and a nested interrupt han-dler is that the interrupts are reenabled early on in the reentrant interrupt handler, which can reduce interrupt latency.
    I can't understand that ?

   thanks!
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  • Note: This was originally posted on 27th June 2008 at http://forums.arm.com

    Hi sim,
          I have not use  Cortex-M3 yet, but the Interrupt chaining you said is very interesting. Could you tell me the how to replace the interrupt vector with new handler to run in details?

    Thanks!

    Sean,


    Interrupt chaining: (an overloaded term) means one of two things; firstly checking for a new pending interrupt before returning from interupt context (i.e. a scenario which would could waste time by unstacking and then straight away restacking the same registers); or secondly, linking handlers together (typically by replacing the interrupt vector with the new handler to run, followed by the new handler calling the original handler). I assume you mean the first.


    hth
    s.
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  • Note: This was originally posted on 27th June 2008 at http://forums.arm.com

    Hi sim,
          I have not use  Cortex-M3 yet, but the Interrupt chaining you said is very interesting. Could you tell me the how to replace the interrupt vector with new handler to run in details?

    Thanks!

    Sean,


    Interrupt chaining: (an overloaded term) means one of two things; firstly checking for a new pending interrupt before returning from interupt context (i.e. a scenario which would could waste time by unstacking and then straight away restacking the same registers); or secondly, linking handlers together (typically by replacing the interrupt vector with the new handler to run, followed by the new handler calling the original handler). I assume you mean the first.


    hth
    s.
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