Interfacing with c and platform dependent sizes

[simendsjo]

On 27.02.2011 11:43, Jacob Carlborg wrote:
> On 2011-02-26 17:58, simendsjo wrote:
>> On 26.02.2011 17:06, Mike Wey wrote:
>>> 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.
>>>
>> Thanks for all the answers. Is something like this correct?
>>
>> version(X86_64)
>> {
>> version(Windows)
>> {
>> version = LLP64;
>> }
>> else version(Posix)
>> {
>> version = LP64;
>> }
>> else
>> {
>> static assert(0);
>> }
>>
>> version(LLP64)
>> {
>> alias short c_short;
>> alias ushort c_ushort;
>> alias int c_int;
>> alias uint c_uint;
>> alias int c_long;
>> alias uint c_ulong;
>> alias long c_longlong;
>> alias ulong c_ulonglong;
>> alias ulong c_size_t;
>> }
>> else version(LP64)
>> {
>> alias short c_short;
>> alias ushort c_ushort;
>> alias int c_int;
>> alias uint c_uint;
>> alias long c_long;
>> alias ulong c_ulong;
>> alias long c_longlong;
>> alias ulong c_ulonglong;
>> alias ulong c_size_t;
>> }
>> else version(ILP64)
>> {
>> alias short c_short;
>> alias ushort c_ushort;
>> alias long c_int;
>> alias ulong c_uint;
>> alias long c_long;
>> alias ulong c_ulong;
>> alias long c_longlong;
>> alias ulong c_ulonglong;
>> alias ulong c_size_t;
>> }
>> else version(SILP64)
>> {
>> alias long c_short;
>> alias ulong c_ushort;
>> alias long c_int;
>> alias ulong c_uint;
>> alias long c_long;
>> alias ulong c_ulong;
>> alias long c_longlong;
>> alias ulong c_ulonglong;
>> alias ulong c_size_t;
>> }
>> else
>> {
>> static assert(0);
>> }
>> }
>> else version(X86)
>> {
>> alias short c_short;
>> alias ushort c_ushort;
>> alias int c_int;
>> alias uint c_uint;
>> alias int c_long;
>> alias uint c_ulong;
>> alias long c_longlong;
>> alias ulong c_ulonglong;
>> alias uint c_size_t;
>> }
>> else
>> {
>> static assert(0);
>> }
>>
>
> I suggest you use core.stdc.config instead, I forgot it existed. BTW
> size_t already exists in D (defined in the object module) and it will be
> the same as size_t in C.
>

Ok. Thanks.