Interfacing with c and platform dependent sizes

[Mike Wey]

On 02/26/2011 11:49 AM, Jacob Carlborg wrote:
> On 2011-02-26 01:28, simendsjo wrote:
>> C is not my strong side, so I'm having some problems wrapping some code.
>>
>> I found a couple of sources on this:
>> 1) http://www.digitalmars.com/d/2.0/htomodule.html
>> 2) http://www.digitalmars.com/d/2.0/interfaceToC.html
>>
>> 1)
>> C's long is the same as D's int.
>> long long is long
>>
>> 2)
>> C 32bit's long long is D's long, C 64 bits long is D's long.
>>
>> So.. A long in C is the same as the platform size? And long long doesn't
>> exist in 64 bit?
>
> In general you can follow the table at
> http://www.digitalmars.com/d/2.0/htomodule.html
>
> But when it comes to "long" in C you have to be careful. On 32bit
> platforms a C "long" will be 32bit long. But on 64bit platforms it
> depends of what data model is used. To simplify things:
>
> * On Windows 64bit a C "long" will be 32bit long
> * On Posix 64bit a C "long" will be 64bit long.
>
> What you can do is to create an alias called "c_long" and "c_ulong",
> something like this:
>
> version (D_LP64)
> {
> version (Windows)
> {
> alias int c_long;
> alias uint c_ulong;
> }
>
> else
> {
> alias long c_long;
> alias ulong c_ulong;
> }
> }
>
> else
> {
> alias int c_long;
> alias uint c_ulong;
> }
>
> To read more about data models:
> http://en.wikipedia.org/wiki/64-bit#Specific_C-language_data_models
>

You can also import core.stdc.config witch defines both c_long and c_ulong.

-- 
Mike Wey