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Date: Sat, 8 Jan 2011 16:00:24 +0100
From: Aurelien Jarno <aurelien@aurel32.net>
Subject: Re: [Qemu-devel] [PATCH 0/7] target-arm: Translate based on TB
	flags, not CPUState
Message-ID: <20110108150024.GA5057@hall.aurel32.net>
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org

On Fri, Jan 07, 2011 at 05:50:51PM +0000, Peter Maydell wrote:
> On 7 January 2011 16:01, Aurelien Jarno <aurelien@aurel32.net> wrote:
> > My other concern is about the definition of the individual bits in the
> > flags. I have seen that you have tried to summarize the usage in the
> > patch 6, but the masks and shifts are still duplicated in different
> > files, which may leads to mistakes if the flags definition are changed.
> >
> > Have you considered using #define as for example in the MIPS target?
> 
> I'll put out a proper v2 patchset in a bit but to save a round,
> are you happy with the following set of #defines?
> (I'm going to drop the comment since the #defines give the
> same info.)
> 
> /* Bit usage in the TB flags field: */
> #define ARM_TBFLAG_THUMB_SHIFT 0
> #define ARM_TBFLAG_THUMB_MASK (1 << ARM_TBFLAG_THUMB_SHIFT)
> #define ARM_TBFLAG_VECLEN_SHIFT 1
> #define ARM_TBFLAG_VECLEN_MASK (0x7 << ARM_TBFLAG_VECLEN_SHIFT)
> #define ARM_TBFLAG_VECSTRIDE_SHIFT 4
> #define ARM_TBFLAG_VECSTRIDE_MASK (0x3 << ARM_TBFLAG_VECSTRIDE_SHIFT)
> #define ARM_TBFLAG_PRIV_SHIFT 6
> #define ARM_TBFLAG_PRIV_MASK (1 << ARM_TBFLAG_PRIV_SHIFT)
> #define ARM_TBFLAG_VFPEN_SHIFT 7
> #define ARM_TBFLAG_VFPEN_MASK (1 << ARM_TBFLAG_VFPEN_SHIFT)
> #define ARM_TBFLAG_CONDEXEC_SHIFT 8
> #define ARM_TBFLAG_CONDEXEC_MASK (0xff << ARM_TBFLAG_CONDEXEC_SHIFT)

I am find with the names, maybe you can align the values for easier
readability, but that's details.

> /* some convenience accessor macros */
> #define ARM_TBFLAG_THUMB(F) \
>     (((F) & ARM_TBFLAG_THUMB_MASK) >> ARM_TBFLAG_THUMB_SHIFT)
> #define ARM_TBFLAG_VECLEN(F) \
>     (((F) & ARM_TBFLAG_VECLEN_MASK) >> ARM_TBFLAG_VECLEN_SHIFT)
> #define ARM_TBFLAG_VECSTRIDE(F) \
>     (((F) & ARM_TBFLAG_VECSTRIDE_MASK) >> ARM_TBFLAG_VECSTRIDE_SHIFT)
> #define ARM_TBFLAG_PRIV(F) \
>     (((F) & ARM_TBFLAG_PRIV_MASK) >> ARM_TBFLAG_PRIV_SHIFT)
> #define ARM_TBFLAG_VFPEN(F) \
>     (((F) & ARM_TBFLAG_VFPEN_MASK) >> ARM_TBFLAG_VFPEN_SHIFT)
> #define ARM_TBFLAG_CONDEXEC(F) \
>     (((F) & ARM_TBFLAG_CONDEXEC_MASK) >> ARM_TBFLAG_CONDEXEC_SHIFT)
> 

Looks fine.

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net