Re: [PATCH] fat: don't use custom hex_to_bin()

[Denys Vlasenko]

On Fri, Sep 23, 2011 at 1:32 PM, Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Cc: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
> ---
>  fs/fat/namei_vfat.c |   22 ++++++----------------
>  1 files changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
> index bb3f29c..09cec4c 100644
> --- a/fs/fat/namei_vfat.c
> +++ b/fs/fat/namei_vfat.c
> @@ -21,6 +21,8 @@
>  #include <linux/slab.h>
>  #include <linux/buffer_head.h>
>  #include <linux/namei.h>
> +#include <linux/kernel.h>
> +
>  #include "fat.h"
>
>  /*
> @@ -505,7 +507,6 @@ xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
>             struct nls_table *nls)
>  {
>        const unsigned char *ip;
> -       unsigned char nc;
>        unsigned char *op;
>        unsigned int ec;
>        int i, k, fill;
> @@ -530,21 +531,10 @@ xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
>                                                return -EINVAL;
>                                        ec = 0;
>                                        for (k = 1; k < 5; k++) {
> -                                               nc = ip[k];
> -                                               ec <<= 4;
> -                                               if (nc >= '0' && nc <= '9') {
> -                                                       ec |= nc - '0';
> -                                                       continue;
> -                                               }
> -                                               if (nc >= 'a' && nc <= 'f') {
> -                                                       ec |= nc - ('a' - 10);
> -                                                       continue;
> -                                               }
> -                                               if (nc >= 'A' && nc <= 'F') {
> -                                                       ec |= nc - ('A' - 10);
> -                                                       continue;
> -                                               }
> -                                               return -EINVAL;
> +                                               int val = hex_to_bin(ip[k]);
> +                                               if (val < 0)
> +                                                       return -EINVAL;
> +                                               ec = (ec << 4) | val;
>                                        }
>                                        *op++ = ec & 0xFF;
>                                        *op++ = ec >> 8;

Function call per byte? That's expensive!
Can't we have a function which converts many sequential bytes?

-- 
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