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Date: Wed, 14 Feb 2024 20:39:35 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>,
	linux-kernel@vger.kernel.org, Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Jani Nikula <jani.nikula@intel.com>
Subject: Re: [RFC] include/linux/make_type.h: Helpers for making u16/u32/u64
 values
Message-ID: <cee345b1-a5aa-41bb-acb7-9b2aaef5bfb5@p183>
References: <ffa107dd-23dd-47e0-b3bb-06c60ca3e2e2@p183>
 <Zcz5GmAtPbdInWJU@smile.fi.intel.com>
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In-Reply-To: <Zcz5GmAtPbdInWJU@smile.fi.intel.com>

On Wed, Feb 14, 2024 at 07:32:10PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 14, 2024 at 08:20:55PM +0300, Alexey Dobriyan wrote:
> 
> ...
> 
> > Secondly,
> > 
> > 	#define make_u64(hi__, lo__)  ((u64)(hi__) << 32 | (u32)(lo__))
> > 
> > doesn't truncate hi, why?
> 
> Because it's not needed (the whole point AFAIU is to override promotion
> to a _signed_ type (int) and here it makes no difference)?

Well,

	make_u64((u64)-1, 0)

will return (u64)-1 unlike

	make_u16((u64)-1, 0)

which will return 0xff00.
BTW, I'm for truncation, but it should be done everywhere.

Thirdly, there were no users posted.