On Fri, Oct 12, 2001 at 12:48:35PM -0700, gavin li wrote:
> First, thanks for your reply!
> I have these two functions:
> void SetCp15(unsigned int uCp15Val)
> {
> asm ("mcr p15, 0, %0, c1, c0, 0;" : "=r"(uCp15Val) :
> );
> }
This is wrong. asm statements are basically:
asm( ... code ... : ... outputs ... : ... inputs ... : ... corrupted ... );
"=r" means "output register" and can only appear in the
"outputs" section.
"r" means "register", and should appear in the inputs
section.
Therefore, your function should have been:
void SetCp15(unsigned int uCp15Val)
{
asm("mcr p15, 0, %0, c1, c0, 0" : : "r" (uCp15Val));
}
> unsigned int ReadCp15()
> {
> unsigned int x;
> asm ("mrc p15, 0, %0, c1, c0, 0;" : "=r"(x) : );
> return x;
> }
This one is fine - there's no need to add a ';' at the end of
the instruction, or the ':' after the outputs if you have
no inputs or corrupted specifications.
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