C99 types VS Linus types

Hello,

before a standard was set, every single OS had to come up with its own fancy fixed-size type definitions such as DWORD, ULONG, u32, CARD32, u_int32_t and so on.

Since C99, the C language has acquired a standard set of machine independent types that can be used for machine independent fixed-width declarations.

Getting rid of all non-ISO types from kernel code could be a desiderable long-term goal. Besides the inexplicable goodness of standards compliance, my favourite argument is that not depending on custom definitions makes copying code from/to other projects a little easier.

Ok, "int32_t" is a little more typing than "s32_t", but in exchange you get it syntax hilighted in vim like built-in types ;-)

I suggest a soft approach: trying to use C99 types as much as possible for new code and only converting old code to C99 when it's not too much trouble.

I hope it doesn't turn into an endless flame war... This is just a polite suggestion.

  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

Please don't send Word attachments - http://www.gnu.org/philosophy/no-word-attachments.html

hi,

alpha user space .h define uint64_t as unsigned long, include/asm-alpha/types.h defines it as unsigned long long. Using a different definition (if it's possible) will be confusing. Using the same definition as user space means than code like:

uint64 t u;
printk("%lu", u);

will not compile on alpha. This problem is solved in C99 by using PRI_xxx format specifier macro, I'm not a great fan of this idea.

surely vim allow to define your own set of type ?

regards,
Philippe Elie

Why is that? Isn't uint64_t supposed to be _always_ a 64bit
unsigned integer? Either the kernel or the user space might be doing the wrong thing...

I've Cc'd the Alpha mantainer to make him aware of this
problem.

This is ugly, but there is no way around it. No matter what
typedefs you're using, C99 or not, printf size specifiers are always bound to plain C types, whose size varies from platform to platform.

Yeah, but not if you're lazy ;-)

  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

Please don't send Word attachments - http://www.gnu.org/philosophy/no-word-attachments.html

I suppose both an 'unsigned long' and 'unsigned long long' are 64-bit entities on the Alpha (which is a 64-bit architecture).

Vojtech Pavlik
SuSE Labs, SuSE CR

uint64_t is always a 64-bit type, and in the case given the compiler emits a warning but the code runs ok.

The problem is that "64-bit long" and "64-bit long long" are different types with the same representation. Which means they are mostly interchangeable, with occasional C weirdness.

-- Jamie