[ECOS] MPC860 PC

[ECOS] MPC860 PC

[Tony Ko]

hi.
I'm wondering that which register is used for PC (program counter) on
MPC860.

thanks in advance.

Tony.

Re: [ECOS] MPC860 PC

[Jonathan Larmour]

Tony Ko wrote:
> 
> hi.
> I'm wondering that which register is used for PC (program counter) on
> MPC860.

Sounds like you need a powerPC programming manual, rather than asking on
the eCos list. How about
http://www.mactech.com/articles/mactech/Vol.10/10.08/PowerPcArchitecture/

or just google search on "powerpc architecture manual".

Jifl
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RE: [ECOS] MPC860 PC

[Nielsen Linus]

Hi Tony!

There is no dedicated, readable register for the PC in the
PowerPC as in other architectures. Programs don't generally
need to know the PC anyway.

However, if you really need to find out the PC, you could try
something like this:

  bl .tmp      ; Branch to the next instruction, saving return address in LR
tmp:
  mfspr r3, lr ; Move LR to r3, voila!

This will put the address of the instruction at tmp
in the r3 register. This will of course overwrite the LR
register, so if you are doing this in a subroutine you
will have to save restore LR afterwards.

Regards,

/Linus


> -----Original Message-----
> From: Tony Ko [ mailto:nhko@gctsemi.com ]
> Sent: den 19 juli 2001 13:50
> To: ecos-discuss@sources.redhat.com
> Subject: [ECOS] MPC860 PC
> 
> 
> hi.
> I'm wondering that which register is used for PC (program counter) on
> MPC860.
> 
> thanks in advance.
> 
> Tony.
> 
>