On 2020-06-29 22:32, Ian Lepore wrote:
On Mon, 2020-06-29 at 14:26 -0600, Warner Losh wrote:
On Mon, Jun 29, 2020, 2:15 PM Ravi Pokala <rpok...@freebsd.org>
wrote:
-----Original Message-----
From: <owner-src-committ...@freebsd.org> on behalf of Hans Petter
Selasky
<hsela...@freebsd.org>
Date: 2020-06-29, Monday at 06:08
To: <src-committ...@freebsd.org>, <svn-src-...@freebsd.org>, <
svn-src-head@freebsd.org>
Subject: svn commit: r362781 -
head/sys/compat/linuxkpi/common/include/linux
Author: hselasky
Date: Mon Jun 29 13:08:40 2020
New Revision: 362781
URL: https://svnweb.freebsd.org/changeset/base/362781
Log:
Implement is_signed(), type_max() and type_min() function
macros in
the
LinuxKPI.
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/sys/compat/linuxkpi/common/include/linux/kernel.h
Modified:
head/sys/compat/linuxkpi/common/include/linux/kernel.h
===================================================================
===========
--- head/sys/compat/linuxkpi/common/include/linux/kernel.h Mon
Jun 29
12:59:09 2020 (r362780)
+++ head/sys/compat/linuxkpi/common/include/linux/kernel.h Mon
Jun 29
13:08:40 2020 (r362781)
@@ -564,4 +564,20 @@ linux_ratelimited(linux_ratelimit_t *rl)
#define __is_constexpr(x) \
__builtin_constant_p(x)
Hi Hans,
+#define is_signed(x) (((x)-1 / (x)2) == (x)0)
It took me several reads to understand this, until I figured out
that 'x'
is not a variable, it's the name of a *type*.
If 'x' is a variable, then '(x)-1' is subtraction, but '(x)2' and
'(x)0'
are nonsensical.
If 'x' is a *type*, then '(x)-1' is typecasting '-1', and similarly
for
'(x)2' and '(x)0'.
So, perhaps a comment, or a better name for 'x'?
I had similar thoughts. Maybe 't' instead?
Or maybe since there's no one-character restriction on macro variable
names, something actually descriptive like 'datatype'.
-- Ian
Warner
Thanks,
Ravi (rpokala@)
Thanks for the feedback. I'll have a look at using a more descriptive
name there for the macro argument.
--HPS
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