From: Pavel Machek <pavel@ucw.cz>
To: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>,
akpm@linux-foundation.org, linux-mips@linux-mips.org,
linux-kernel@vger.kernel.org,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
"Rafael J . Wysocki" <rjw@sisk.pl>,
zhangfx@lemote.com, linux-laptop@vger.kernel.org,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH v8 5/8] Loongson: YeeLoong: add hardware monitoring driver
Date: Sun, 6 Dec 2009 09:47:17 +0100 [thread overview]
Message-ID: <20091206084717.GD2766@ucw.cz> (raw)
In-Reply-To: <d8789fa7e97d8a170c4e2516d7ef2d2fbbe42cc6.1260082252.git.wuzhangjin@gmail.com>
Hi!
> +static int get_battery_current(void)
> +{
> + s16 value;
> +
> + value = (ec_read(REG_BAT_CURRENT_HIGH) << 8) |
> + (ec_read(REG_BAT_CURRENT_LOW));
> +
> + if (value < 0)
> + value = ~value + 1;
> +
> + return value;
> +}
What is going on here? I thought the value is already in two's
complement... Is the above equivalent of
if (value < 0)
value = -value;
? If so, why? If not, can you add a comment?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2009-12-06 8:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-06 7:01 [PATCH v8 0/8] Loongson: YeeLoong: add platform drivers Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 1/8] MIPS: add subdirectory for platform extension drivers Wu Zhangjin
2009-12-08 7:37 ` Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 2/8] Loongson: YeeLoong: add platform driver Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 3/8] Loongson: YeeLoong: add backlight driver Wu Zhangjin
2009-12-08 7:52 ` Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 4/8] Loongson: YeeLoong: add battery driver Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 5/8] Loongson: YeeLoong: add hardware monitoring driver Wu Zhangjin
2009-12-06 8:47 ` Pavel Machek [this message]
2009-12-07 0:54 ` Wu Zhangjin
2009-12-07 8:04 ` Pavel Machek
2009-12-07 9:41 ` Wu Zhangjin
2009-12-07 9:49 ` Pavel Machek
2009-12-07 11:01 ` Wu Zhangjin
2009-12-08 7:09 ` Pavel Machek
2009-12-08 7:26 ` Wu Zhangjin
2009-12-08 6:50 ` Wu Zhangjin
2009-12-08 7:06 ` Pavel Machek
2009-12-08 7:18 ` Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 6/8] Loongson: YeeLoong: add video output driver Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 7/8] Loongson: YeeLoong: add suspend support Wu Zhangjin
2009-12-06 7:01 ` [PATCH v8 8/8] Loongson: YeeLoong: add input/hotkey driver Wu Zhangjin
2009-12-07 6:48 ` Dmitry Torokhov
2009-12-07 7:26 ` Wu Zhangjin
2009-12-08 6:52 ` Wu Zhangjin
2009-12-08 7:23 ` Dmitry Torokhov
2009-12-08 7:34 ` Wu Zhangjin
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