linux-kernel - Re: [PATCH V2 1/2] lib/string: add memrchr function

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Message-ID: <20190214125347.GU9224@smile.fi.intel.com>
Date:   Thu, 14 Feb 2019 14:53:47 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Xiang Xiao <xiaoxiang781216@...il.com>
Cc:     rdunlap@...radead.org, gregkh@...uxfoundation.org,
        alexander.shishkin@...ux.intel.com, ohad@...ery.com,
        bjorn.andersson@...aro.org, wendy.liang@...inx.com,
        arnaud.pouliquen@...com, kumar.gala@...aro.org,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xiang Xiao <xiaoxiang@...omi.com>
Subject: Re: [PATCH V2 1/2] lib/string: add memrchr function

On Thu, Feb 14, 2019 at 02:02:37PM +0800, Xiang Xiao wrote:
> Here is the detailed description for memrchr:
> 
> void *memrchr(const void *s, int c, size_t n);
> 
> The memrchr() function is like the memchr() function, except
> that it searches backward from the end of the n bytes pointed
> to by s instead of forward from the beginning.
> 
> The memrchr() functions return a pointer to the matching byte
> or NULL if the character does not occur in the given memory
> area.

> +void *memrchr(const void *s, int c, size_t n)
> +{
> +	const unsigned char *p = s + n;
> +
> +	while (n-- != 0) {

Simple:

	while (n--) {

> +		if ((unsigned char)c == *--p)
> +			return (void *)p;
> +	}
> +	return NULL;
> +}

-- 
With Best Regards,
Andy Shevchenko