Subject: Re: [Ltt-dev] [PATCH 7/10] local_t : powerpc

From: Mathieu Desnoyers <[email-masked]>
Date: Wed, 20 Dec 2006 22:34:23 -0500

* Mathieu Desnoyers ([email-masked]) wrote:
> --- a/include/asm-powerpc/local.h
> +++ b/include/asm-powerpc/local.h
> +/**
> + * local_add_unless - add unless the number is a given value
> + * @l: pointer of type local_t
> + * @a: the amount to add to l...
> + * @u: ...unless l is equal to u.
> + *
> + * Atomically adds @a to @l, so long as it was not @u.
> + * Returns non-zero if @l was not @u, and zero otherwise.
> + */
> +static __inline__ int local_add_unless(local_t *l, long a, long u)
> +{
> +	long t;
> +
> +	__asm__ __volatile__ (
> +"1:	ldarx	%0,0,%1		# local_add_unless\n\
> +	cmpd	0,%0,%3 \n\
> +	beq-	2f \n\
> +	add	%0,%2,%0 \n"
> +	PPC405_ERR77(0,%2)

Sorry, the previous line is unnecessary : PPC405 is a 32 bits arch errata and
this code is compiled on 64 bits arch only.

> +"	stdcx.	%0,0,%1 \n\
> +	bne-	1b \n"
> +"	subf	%0,%2,%0 \n\
> +2:"
> +	: "=&r" (t)
> +	: "r" (&(l->a.counter)), "r" (a), "r" (u)
> +	: "cc", "memory");
> +
> +	return t != u;
> +}
> +

Mathieu

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