Re: [Qemu-devel] [PATCH 1/2] target-arm: Move Neon VUZP to a helper function

[Nathan Froyd <froydnj@codesourcery.com>]

On Fri, Feb 11, 2011 at 04:53:30PM +0000, Peter Maydell wrote:
> On 11 February 2011 16:14, Peter Maydell <peter.maydell@linaro.org> wrote:
> > +void HELPER(neon_unzip)(CPUState *env, uint32_t insn)
> > +{
> > +    int rd = ((insn >> 18) & 0x10) | ((insn >> 12) & 0x0f);
> > +    int rm = ((insn >> 1) & 0x10) | (insn & 0x0f);
> > +    int size = (insn >> 18) & 3;
> > +    if (insn & 0x40) { /* Q */
> > +        uint64_t zm0 = float64_val(env->vfp.regs[rm]);
> > +        uint64_t zm1 = float64_val(env->vfp.regs[rm + 1]);
> > +        uint64_t zd0 = float64_val(env->vfp.regs[rd]);
> > +        uint64_t zd1 = float64_val(env->vfp.regs[rd + 1]);
> 
> I can rework these patches if people don't like the way this is
> effectively doing decoding in a helper function, incidentally,
> although I'm not convinced it would end up any nicer overall.

I do think the preferred way would be to extract rd, rm, size, and Q
up-front, rather than having the helper twiddle instruction bits.

-Nathan