Lpc2000

Robert Adsett wrote:
> At 12:04 AM 3/26/2006 +0100, Sten wrote:
> 
>>Wonderful! ;-)
>>But why to save r0..r3 and ip in your irq_isr?!? Only lr will be changed 
>>by bl and registers used by
>>irq_handler() should be saved in its function prologue by irq_handler() 
>>itself!
> 
> 
> According to the APCS "A (called)subroutine must preserve the contents of 
> the registers r4-r8, r10, r11 and SP ".
> 
> R0-R3 are temporary/parameter registers and must be saved by the caller if 
> needed  R12 is the intra-procedure call scratch register so similar 
> restrictions apply to it, R14 is the link register so make sure you've 
> saved it properly or you won't be able to return.
> 
> That leaves R9 the platform specific register, which I believe gcc treats 
> the same as r4-r8 (I can't lay my hands on my reference for that at the 
> moment).
> 


Ok, this makes sense...

  Sten

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