Subject: Re: [v2,2/2] powerpc32: add support for csum_add()

From: Scott Wood <[email-masked]>
Date: Mon, 30 Mar 2015 22:14:30 -0500

On Tue, Feb 03, 2015 at 12:39:27PM +0100, LEROY Christophe wrote:
> The C version of csum_add() as defined in include/net/checksum.h gives the
> following assembly:
>        0:       7c 04 1a 14     add     r0,r4,r3
>        4:       7c 64 00 10     subfc   r3,r4,r0
>        8:       7c 63 19 10     subfe   r3,r3,r3
>        c:       7c 63 00 50     subf    r3,r3,r0
> 
> include/net/checksum.h also offers the possibility to define an arch specific
> function.
> This patch provides a ppc32 specific csum_add() inline function.
> 
> Signed-off-by: Christophe Leroy <[email-masked]>
> ---
> v2: changed constraints on the __asm__
> 
>  arch/powerpc/include/asm/checksum.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/checksum.h b/arch/powerpc/include/asm/checksum.h
> index cfe806a..1e48cc7 100644
> --- a/arch/powerpc/include/asm/checksum.h
> +++ b/arch/powerpc/include/asm/checksum.h
> @@ -141,6 +141,18 @@ static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
>  {
>  	return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
>  }
> +
> +#define HAVE_ARCH_CSUM_ADD
> +static inline __wsum csum_add(__wsum csum, __wsum addend)
> +{
> +    __asm__("\n\

s/__asm__/asm/

Use tabs to indent

> +	addc %0,%0,%1 \n\
> +	addze %0,%0 \n\

Use ; to separate asm statements instead of using \n
Use string concatenation instead of \

-Scott