Re: [PATCH 02/16] math128, x86_64: Implement {mul,add}_u128 in 64bitasm

[Juri Lelli]

On 10/24/2012 03:27 PM, H. Peter Anvin wrote:
> On 10/24/2012 02:53 PM, Juri Lelli wrote:
> > diff --git a/arch/x86/include/asm/math128.h b/arch/x86/include/asm/math128.h
> > new file mode 100644
> > index 0000000..c0e2a6c
> > --- /dev/null
> > +++ b/arch/x86/include/asm/math128.h
> > @@ -0,0 +1,39 @@
> > +#ifndef _ASM_MATH128_H
> > +#define _ASM_MATH128_H
> > +
> > +#ifdef CONFIG_X86_64
> > +
> > +#ifdef __SIZEOF_INT128__
> > +#define ARCH_HAS_INT128
> > +#endif
> > +
> > +#ifndef ARCH_HAS_INT128
> > +
> > +static inline u128 mul_u64_u64(u64 a, u64 b)
> > +{
> > +       u128 res;
> > +
> > +       asm("mulq %2"
> > +               : "=a" (res.lo), "=d" (res.hi)
> > +               :  "rm" (b), "0" (a));
> > +
> > +       return res;
> > +}
> > +#define mul_u64_u64 mul_u64_u64
> > +
> > +static inline u128 add_u128(u128 a, u128 b)
> > +{
> > +       u128 res;
> > +
> > +       asm("addq %2,%0;\n"
> > +           "adcq %3,%1;\n"
> > +               : "=rm" (res.lo), "=rm" (res.hi)
> > +               : "r" (b.lo), "r" (b.hi), "0" (a.lo), "1" (a.hi));
> > +
> > +       return res;
> > +}
> > +#define add_u128 add_u128
> > +
>
> How could this work since u128 presumably has not yet been defined as a
> structure?  After all, isn't it the absence of ARCH_HAS_INT128 which
> makes that happen?

Sorry, you were not in the Cc list of the previous patch in the patchset,
so you probably missed that. I should have triple checked git send-email
Cc list. Sorry about that.

I'll add you there.

Thanks and Regards,

- Juri
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/