* [U-Boot] io.h
@ 2009-12-19 8:10 seyyed morteza havaedgi
2010-01-05 19:59 ` Scott Wood
0 siblings, 1 reply; 2+ messages in thread
From: seyyed morteza havaedgi @ 2009-12-19 8:10 UTC (permalink / raw)
To: u-boot
hi wolfgang
I working on mpc8272. in the file io.h there is "twi 0,RA,0" instruction.
what this instruction means and what it does? In accordance with powerpc programmers manual this instruction must do nothing because the TO field is zero.
thanks a lot,
seyyed morteza havaedgi.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [U-Boot] io.h
2009-12-19 8:10 [U-Boot] io.h seyyed morteza havaedgi
@ 2010-01-05 19:59 ` Scott Wood
0 siblings, 0 replies; 2+ messages in thread
From: Scott Wood @ 2010-01-05 19:59 UTC (permalink / raw)
To: u-boot
On Sat, Dec 19, 2009 at 11:40:40AM +0330, seyyed morteza havaedgi wrote:
> I working on mpc8272. in the file io.h there is "twi 0,RA,0" instruction.
> what this instruction means and what it does? In accordance with powerpc programmers manual this instruction must do nothing because the TO field is zero.
It turns a data dependency on RA into a flow control dependency (even though
the decision always ends up being not to trap), which can then be ordered by
a following isync.
-Scott
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