From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: [PATCH 2/7] stdlib: Simplify getenv
Date: Thu, 16 Feb 2023 18:47:52 +0000 [thread overview]
Message-ID: <PAWPR08MB8982515DC6EBA8DA56B347AD83A09@PAWPR08MB8982.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <1809ebdf-e032-c34f-f685-d6718d525c2c@linaro.org>
Hi Adhemerval,
> Do you mean something like:
>
> size_t len = strlen (name);;
> for (char **ep = __environ; *ep != NULL; ++ep)
> {
> if (((*ep)[0] == name[0] && (*ep)[1] == '=')
> || (strncmp (name, *ep, len) == 0 && (*ep)[len] == '='))
> return *ep + len + 1;
> }
No I meant checking the first character first before doing more expensive calls, so:
if (name[0] == (*ep)[0] && strncmp (name, *ep, len) == 0 && (*ep)[len] == '=')
return *ep + len + 1;
Basically this means you get a very tight loop checking the first character - this avoids
most calls to strncmp. This is basically the same result as the current implementation
but without all the defines and complex unaligned/big-endian stuff!
Cheers,
Wilco
next prev parent reply other threads:[~2023-02-16 18:48 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-13 13:55 [PATCH 0/7] Remove _STRING_ARCH_unaligned Adhemerval Zanella
2023-02-13 13:55 ` [PATCH 1/7] crypto: Remove _STRING_ARCH_unaligned usage Adhemerval Zanella
2023-02-15 17:55 ` Wilco Dijkstra
2023-02-13 13:55 ` [PATCH 2/7] stdlib: Simplify getenv Adhemerval Zanella
2023-02-15 17:50 ` Wilco Dijkstra
2023-02-16 13:49 ` Adhemerval Zanella Netto
2023-02-16 14:02 ` Andreas Schwab
2023-02-16 18:02 ` Wilco Dijkstra
2023-02-16 18:38 ` Adhemerval Zanella Netto
2023-02-16 18:47 ` Wilco Dijkstra [this message]
2023-02-16 19:29 ` Adhemerval Zanella Netto
2023-02-17 17:13 ` Wilco Dijkstra
2023-02-13 13:55 ` [PATCH 3/7] nscd: Remove _STRING_ARCH_unaligned usage Adhemerval Zanella
2023-02-15 17:59 ` Wilco Dijkstra
2023-02-13 13:55 ` [PATCH 4/7] resolv: " Adhemerval Zanella
2023-02-15 18:04 ` Wilco Dijkstra
2023-02-13 13:55 ` [PATCH 5/7] iconv: Remove _STRING_ARCH_unaligned usage for get/set macros Adhemerval Zanella
2023-02-13 14:05 ` Andreas Schwab
2023-02-15 18:34 ` Wilco Dijkstra
2023-02-13 13:55 ` [PATCH 6/7] iconv: Remove _STRING_ARCH_unaligned usage Adhemerval Zanella
2023-02-15 19:02 ` Wilco Dijkstra
2023-02-13 13:55 ` [PATCH 7/7] string: Remove string_private.h Adhemerval Zanella
2023-02-15 19:04 ` Wilco Dijkstra
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