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From: Paul Eggert <eggert@cs.ucla.edu>
To: Alejandro Colomar <colomar.6.4.3@gmail.com>
Cc: Florian Weimer <fweimer@redhat.com>,
	Alejandro Colomar via Libc-alpha <libc-alpha@sourceware.org>,
	linux-man@vger.kernel.org, gcc-patches@gcc.gnu.org,
	mtk.manpages@gmail.com
Subject: Re: [PATCH 1/4] system_data_types.7: Add '__int128'
Date: Fri, 2 Oct 2020 13:19:24 -0700
Message-ID: <936422e4-d292-d435-6c3c-333b924b8ad0@cs.ucla.edu> (raw)
In-Reply-To: <be53c11a-1729-e895-e5a5-b9b6a42f29de@gmail.com>

On 10/2/20 1:03 PM, Alejandro Colomar wrote:
> I know it's not in stdint,
> but I mean that it behaves as any other stdint type.

It doesn't. There's no portable way to use scanf and printf on it. You can't 
reliably convert it to intmax_t. It doesn't have the associated _MIN and _MAX 
macros that the stdint types do. It's a completely different animal.

If all you need are a few bit-twiddling tricks on x86-64, it should work. But 
watch out if you try to do something fancy, like multiply or divide or read or 
print or atomics. There's a good reason it's excluded from intmax_t.

  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01 16:34 [PATCH 0/4] Document 128-bit types Alejandro Colomar
2020-10-01 16:34 ` [PATCH 1/4] system_data_types.7: Add '__int128' Alejandro Colomar
2020-10-02 11:47   ` Florian Weimer
2020-10-02 17:52     ` Paul Eggert
2020-10-02 19:01       ` Alejandro Colomar
2020-10-02 19:54         ` Paul Eggert
2020-10-02 20:03           ` Alejandro Colomar
2020-10-02 20:19             ` Paul Eggert [this message]
2020-10-02 23:44               ` Alejandro Colomar
2020-10-02 23:53                 ` Paul Eggert
2020-10-05  7:12           ` Florian Weimer
2020-10-07  6:53             ` Michael Kerrisk (man-pages)
2020-10-07  6:57               ` Florian Weimer
2020-10-01 16:34 ` [PATCH 2/4] __int128.3: New link to system_data_types(7) Alejandro Colomar
2020-10-01 16:34 ` [PATCH 3/4] system_data_types.7: Add 'unsigned __int128' Alejandro Colomar
2020-10-01 16:34 ` [PATCH 4/4] unsigned-__int128.3: New link to system_data_types(7) Alejandro Colomar
2020-10-02 12:28 ` [PATCH v2 0/4] Document 128-bit types Alejandro Colomar
2020-10-02 12:28 ` [PATCH v2 1/4] system_data_types.7: Add '__int128' Alejandro Colomar
2020-10-02 12:28 ` [PATCH v2 2/4] __int128.3: New link to system_data_types(7) Alejandro Colomar
2020-10-02 12:28 ` [PATCH v2 3/4] system_data_types.7: Add 'unsigned __int128' Alejandro Colomar
2020-10-02 12:28 ` [PATCH v2 4/4] unsigned-__int128.3: New link to system_data_types(7) Alejandro Colomar

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