From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kMrgi-0005nv-W3 for barebox@lists.infradead.org; Mon, 28 Sep 2020 11:51:25 +0000 References: <20200914095948.16811-1-a.fatoum@pengutronix.de> <20200928093102.GA12463@pengutronix.de> From: Ahmad Fatoum Message-ID: Date: Mon, 28 Sep 2020 13:51:22 +0200 MIME-Version: 1.0 In-Reply-To: <20200928093102.GA12463@pengutronix.de> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] readkey: shrink table of known escape sequences in size To: Sascha Hauer Cc: barebox@lists.infradead.org Hello Sascha, On 9/28/20 11:31 AM, Sascha Hauer wrote: > On Mon, Sep 14, 2020 at 11:59:48AM +0200, Ahmad Fatoum wrote: >> Instead of storing pointers to 4-byte strings, we could just store the >> characters directly in the struct. Can save us up to 18 pointers worth >> of space. Additionally, the nul byte need not be stored explicitly for >> 3-byte strings, if we know those are the largest strings we have. >> >> The latter likely does not save us any space because of the usual >> alignment rules, but it will allow us to support sequences one byte >> bigger in future at no increase in size. >> >> Signed-off-by: Ahmad Fatoum >> --- >> lib/readkey.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/lib/readkey.c b/lib/readkey.c >> index c26e9d51aba9..551296de3eb6 100644 >> --- a/lib/readkey.c >> +++ b/lib/readkey.c >> @@ -20,8 +20,10 @@ >> #include >> #include >> >> +#define MAX_ESC_LEN 3 >> + >> struct esc_cmds { >> - const char *seq; >> + const char seq[MAX_ESC_LEN]; > > I would have expected that when this array is initialized with a static > initializer, the compiler would add a \0 at the end. Apparently this is > not the case, initializing this 3 byte array with "[6~" is perfectly > fine for the compiler. Initializers are padded with zeroes if they are too short. >> @@ -49,7 +51,7 @@ static const struct esc_cmds esccmds[] = { >> int read_key(void) >> { >> unsigned char c; >> - unsigned char esc[5]; >> + unsigned char esc[MAX_ESC_LEN + 2]; >> c = getchar(); >> >> if (c == 27) { >> @@ -67,7 +69,7 @@ int read_key(void) >> } >> esc[i] = 0; >> for (i = 0; i < ARRAY_SIZE(esccmds); i++){ >> - if (!strcmp(esc, esccmds[i].seq)) >> + if (!strncmp(esc, esccmds[i].seq, MAX_ESC_LEN)) >> return esccmds[i].val; > > Anyway, I don't think we should play tricks with dropping string > termination characters just to squeeze some bytes out of the binary. I can define #define MAX_ESC_LEN 4 if you prefer that, but I consider it superfluous. Cheers, Ahmad > > Sascha > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox