From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 12 Sep 2012 18:35:56 GMT
Subject: Re: [PATCH 1/3] sha1: update pointer and remaining length after subfunction call
Message-ID: <7vhar3ccmr.fsf@alter.siamese.dyndns.org>
In-Reply-To: <e6f0051409811fc57385ae712d3256772044bf09.1347442430.git.ydroneaud@opteya.com>

Yann Droneaud <ydroneaud@opteya.com> writes:

> There's no need to update the pointer and remaining length before
> leaving or calling the SHA1 sub function.
>
> Additionnaly, the partial block code could be looking more like
> the full block handling branch.
>
> Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
> ---
>  block-sha1/sha1.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
> index a8d4bf9..c1af112 100644
> --- a/block-sha1/sha1.c
> +++ b/block-sha1/sha1.c
> @@ -248,11 +248,11 @@ void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
>  			left = len;
>  		memcpy(lenW + (char *)ctx->W, data, left);
>  		lenW = (lenW + left) & 63;
> -		len -= left;
> -		data = ((const char *)data + left);
>  		if (lenW)
>  			return;
>  		blk_SHA1_Block(ctx, ctx->W);
> +		data = ((const char *)data + left);
> +		len -= left;
>  	}
>  	while (len >= 64) {
>  		blk_SHA1_Block(ctx, data);

It is not wrong per-se, but doesn't the compiler optimize it out if
this is worth doing?  Just being curious.