Re: [Qemu-trivial] [PATCH v1 1/5] block/nand: Factor out common code

[Michael Tokarev <mjt@tls.msk.ru>]

18.06.2013 15:08, peter.crosthwaite@xilinx.com wrote:
> From: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> 
> Most of this computation of s->iolen is the same for both the if and
> else paths here. Factor out the common parts outside the if.
> 
> Cc: qemu-trivial@nongnu.org
> 
> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> ---
> 
>  hw/block/nand.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/block/nand.c b/hw/block/nand.c
> index 087ca14..6309f93 100644
> --- a/hw/block/nand.c
> +++ b/hw/block/nand.c
> @@ -272,10 +272,10 @@ static void nand_command(NANDFlashState *s)
>              break;
>          offset = s->addr & ((1 << s->addr_shift) - 1);
>          s->blk_load(s, s->addr, offset);
> -        if (s->gnd)
> -            s->iolen = (1 << s->page_shift) - offset;
> -        else
> -            s->iolen = (1 << s->page_shift) + (1 << s->oob_shift) - offset;
> +        s->iolen = (1 << s->page_shift) - offset;
> +        if (!s->gnd) {
> +            s->iolen += 1 << s->oob_shift;
> +        }

Hm.  Can s->iolen become negative here?

addr_shift can be either less or greather than page_shift.  When addr_shift
is larger than page_shift (addr_shift=16, page_shift=11), offset may be up
to 65535, in which case s->iolen may be -63487, even without additional
oob_shift.

I dunno if this is a concern, just.. asking.

Besides, exactly the same expression is used in nand_getio() down this file,
maybe a common function is in order? :)

And looking at this file, I think it deserves some good type changes.  For
example, all these _shift are unsigned, and most are actually used as masks,
in form (1<<shift), instead of directly (except of erase_shift).

Thanks,

/mjt