[ECOS] about interrupts nesting and vector number decoding

yyl ylyuan@davform.com
Tue Oct 24 20:38:00 GMT 2000


Hi,i have tow questions need your 
help.
Q1:From document,i know that isr is 
excuted with interrupt disabled,but dsr enable interrupt,so i think the 
interrupt nesting is occured  in dsr.But from another place in the 
document,something is said as followed:
  
      The 
VSR should follow the following approximate plan:
          
........ 
          (Optional) 
Re-enable interrupts to permit nesting. 
          Decode the actual 
external interrupt being delivered from the interrupt controller. This will 
yield the ISR vector number. 
          Using the ISR 
vector number as an index, retrieve the ISR pointer and its data pointer from 
the ISR vector table.  
          Construct a C call 
stack frame. 
 
If re-enable interrupts before isr being called ,it seems that in isr 
interrupt is enabled.
Who can tell me the procedure  about the interrupt nesting?
Q2:i think the macro of  hal_intc_decode in the file variant.inc only 
decodes the vector from SIU level,i don't find the code decoding
the vector using the rigester CIVR of CPM?
     Thanks!



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