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From: David Laight <David.Laight@ACULAB.COM>
To: David Laight <David.Laight@ACULAB.COM>,
	'Holger Lubitz' <holger.lubitz@t-online.de>,
	'Linus Torvalds' <torvalds@linux-foundation.org>,
	Guenter Roeck <linux@roeck-us.net>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-kbuild@vger.kernel.org" <linux-kbuild@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"linux-toolchains@vger.kernel.org"
	<linux-toolchains@vger.kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"linux-m68k@lists.linux-m68k.org"
	<linux-m68k@lists.linux-m68k.org>
Subject: RE: [PATCH v2] kbuild: treat char as always unsigned
Date: Fri, 30 Dec 2022 13:13:55 +0000	[thread overview]
Message-ID: <a296bd41278d4bd4a4e9f0d31a540613@AcuMS.aculab.com> (raw)
In-Reply-To: <357cbd67260040e4bcf17d519aaafdcb@AcuMS.aculab.com>

....
> > int strcmp1(const char *cs, const char *ct)
> > {
> >         int res;
> >
> >         asm ("\n"
> >                 "1: move.b  (%0)+,%2\n"  /* get *cs */
> >                 "   jeq     2f\n"        /* end of first string? */
> >                 "   cmp.b   (%1)+,%2\n"  /* compare *ct */
> >                 "   jeq     1b\n"        /* if equal, continue */
> >                 "   jra     3f\n"        /* else skip to tail */
> >                 "2: cmp.b   (%1)+,%2\n"  /* compare one last byte */
> >                 "3: subx.l  %2, %2\n"    /* -1 if borrow, 0 if not */
> >                 "   jls     4f\n"        /* if set, z is from sub.b */
> 
> The subx will set Z unless C was set.
> So that doesn't seem right.

Clearly my brain was asleep earlier.
subx will clear Z not set it.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  reply	other threads:[~2022-12-30 13:14 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Y1BcpXAjR4tmV6RQ@zx2c4.com>
     [not found] ` <20221019203034.3795710-1-Jason@zx2c4.com>
2022-12-21 14:53   ` [PATCH v2] kbuild: treat char as always unsigned Guenter Roeck
2022-12-21 15:05     ` Geert Uytterhoeven
2022-12-21 15:23       ` Guenter Roeck
2022-12-21 15:29       ` Rasmus Villemoes
2022-12-21 15:56         ` Guenter Roeck
2022-12-21 17:06           ` Linus Torvalds
2022-12-21 17:19             ` Guenter Roeck
2022-12-21 18:46               ` Linus Torvalds
2022-12-21 19:08                 ` Linus Torvalds
2022-12-21 21:01                 ` Guenter Roeck
2022-12-22 13:05                 ` Geert Uytterhoeven
2022-12-22 10:41             ` David Laight
     [not found]               ` <f02e0ac7f2d805020a7ba66803aaff3e31b5eeff.camel@t-online.de>
2022-12-24  9:47                 ` Geert Uytterhoeven
2022-12-30 11:39                 ` David Laight
2022-12-30 13:13                   ` David Laight [this message]
2023-01-02  8:29                   ` Geert Uytterhoeven
2022-12-21 17:49           ` Andreas Schwab
2022-12-21 16:57         ` Geert Uytterhoeven

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