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| Returning from Exception http://www.at91.com/samphpbb/viewtopic.php?f=15&t=13569 |
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| Author: | per.h [ Wed May 06, 2009 3:33 pm ] |
| Post subject: | Returning from Exception |
Hello, A return from IRQ or SVC is done with the commands: SUBS PC, R14_irq, #4 and MOVS PC, R14_svc But I am puzzled by the way the processor know to return to usermode. Whats the magic that makes the processor change state ? .. according to the instruction set manual the commands copy the Link register to the PC - that makes the CPU jump, but not change mode ? - the S is supposed to change the 4 ALU bits. Sincerely Per Hansen |
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| Author: | wzinet [ Tue Oct 26, 2010 10:22 pm ] |
| Post subject: | Re: Returning from Exception |
Hi, I'm also interested in this - did you ever get a resolution? Thanks, |
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| Author: | Crossware [ Wed Oct 27, 2010 4:17 pm ] |
| Post subject: | Re: Returning from Exception |
The current program status register (CPSR) is also restored (from the appropriate SPSR). Bes regards Crossware http://www.crossware.com |
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