Re: [PATCH nf-next] lib/ts_bm: add helper to reduce indentation and improve readability

[Jeremy Sowden <jeremy@azazel.net>]

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On 2023-06-20, at 19:09:25 +0100, Jeremy Sowden wrote:
> The flow-control of `bm_find` is very deeply nested with a conditional
> comparing a ternary expression against the pattern inside a for-loop
> inside a while-loop inside a for-loop.
> 
> Move the inner for-loop into a helper function to reduce the amount of
> indentation and make the code easier to read.
> 
> Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
> ---
>  lib/ts_bm.c | 42 +++++++++++++++++++++++++++++-------------
>  1 file changed, 29 insertions(+), 13 deletions(-)

Sent the wrong version.  Apologies.

J.

> diff --git a/lib/ts_bm.c b/lib/ts_bm.c
> index 1f2234221dd1..d74fdb87d269 100644
> --- a/lib/ts_bm.c
> +++ b/lib/ts_bm.c
> @@ -55,6 +55,24 @@ struct ts_bm
>  	unsigned int	good_shift[];
>  };
>  
> +static bool patmtch(const u8 *pattern, const u8 *text, unsigned int patlen,
> +		    bool icase)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < patlen; i++) {
> +		u8 t = *(text-i);
> +
> +		if (icase)
> +			t = toupper(t);
> +
> +		if (t != *(pattern-i))
> +			return false;
> +	}
> +
> +	return true;
> +}
> +
>  static unsigned int bm_find(struct ts_config *conf, struct ts_state *state)
>  {
>  	struct ts_bm *bm = ts_config_priv(conf);
> @@ -70,19 +88,17 @@ static unsigned int bm_find(struct ts_config *conf, struct ts_state *state)
>  			break;
>  
>  		while (shift < text_len) {
> -			DEBUGP("Searching in position %d (%c)\n", 
> -				shift, text[shift]);
> -			for (i = 0; i < bm->patlen; i++) 
> -				if ((icase ? toupper(text[shift-i])
> -				    : text[shift-i])
> -					!= bm->pattern[bm->patlen-1-i])
> -				     goto next;
> -
> -			/* London calling... */
> -			DEBUGP("found!\n");
> -			return consumed + (shift-(bm->patlen-1));
> -
> -next:			bs = bm->bad_shift[text[shift-i]];
> +			DEBUGP("Searching in position %d (%c)\n",
> +			       shift, text[shift]);
> +
> +			if (patmtch(&bm->pattern[bm->patlen-1], &text[shift],
> +				    bm->patlen, icase)) {
> +				/* London calling... */
> +				DEBUGP("found!\n");
> +				return consumed + (shift-(bm->patlen-1));
> +			}
> +
> +			bs = bm->bad_shift[text[shift-i]];
>  
>  			/* Now jumping to... */
>  			shift = max_t(int, shift-i+bs, shift+bm->good_shift[i]);
> -- 
> 2.39.2
> 

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