im having problem in code below, while making my own file handler. the data stored in buffer, so i can recall portion of data in diff format and length like int,short,etc.  but im stuck with function getb() below. any suggestion? thks.

struct T_FILE_RAM {
  ubyte[] buffer;
  int offset;

void getb(void* buf, int size) {
	buf=&b[offset..offset+size]; //<-- prob here
}

void read(out uint x) { getb(&x, x.sizeof); }
void read(out ushort x) { getb(&x, x.sizeof); }

}

"James" wrote
> im having problem in code below, while making my own file handler. the data stored in buffer, so i can recall portion of data in diff format and length like int,short,etc.  but im stuck with function getb() below. any suggestion? thks.
>
> struct T_FILE_RAM {
>  ubyte[] buffer;
>  int offset;
>
> void getb(void* buf, int size) {
> buf=&b[offset..offset+size]; //<-- prob here
> }
>
> void read(out uint x) { getb(&x, x.sizeof); }
> void read(out ushort x) { getb(&x, x.sizeof); }
>
> }

I think you meant this?

buf[0..size] = buffer[offset..offset+size];
And also, you need to increment offset, no?
offset += size.

I'd also recommend using a template:

void getb(T)(ref T t)
{
    auto size = t.sizeof;
    auto buf = (cast(ubyte *)&t)[0..size];
    buf[] = buffer[offset..offset+size];
    offset += size;
}

Now you don't need to implement each type, and you can call like this:
int x;
ushort y;
getb(x); // reads 4 bytes
getb(y); // reads 2 bytes

-Steve

On Thu, 06 Nov 2008 18:22:36 +0300, Steven Schveighoffer <schveiguy@yahoo.com> wrote:

> "James" wrote
>> im having problem in code below, while making my own file handler. the
>> data stored in buffer, so i can recall portion of data in diff format and
>> length like int,short,etc.  but im stuck with function getb() below. any
>> suggestion? thks.
>>
>> struct T_FILE_RAM {
>>  ubyte[] buffer;
>>  int offset;
>>
>> void getb(void* buf, int size) {
>> buf=&b[offset..offset+size]; //<-- prob here
>> }
>>
>> void read(out uint x) { getb(&x, x.sizeof); }
>> void read(out ushort x) { getb(&x, x.sizeof); }
>>
>> }
>
> I think you meant this?
>
> buf[0..size] = buffer[offset..offset+size];
> And also, you need to increment offset, no?
> offset += size.
>
> I'd also recommend using a template:
>
> void getb(T)(ref T t)
> {
>     auto size = t.sizeof;
>     auto buf = (cast(ubyte *)&t)[0..size];
>     buf[] = buffer[offset..offset+size];
>     offset += size;
> }
>
> Now you don't need to implement each type, and you can call like this:
> int x;
> ushort y;
> getb(x); // reads 4 bytes
> getb(y); // reads 2 bytes
>
> -Steve
>
>

Good solution also cares about endianess.

Also take a look at tango.io.protocol - it should cover all your needs.

Steven Schveighoffer Wrote:

> "James" wrote
> > im having problem in code below, while making my own file handler. the data stored in buffer, so i can recall portion of data in diff format and length like int,short,etc.  but im stuck with function getb() below. any suggestion? thks.
> >
> > struct T_FILE_RAM {
> >  ubyte[] buffer;
> >  int offset;
> >
> > void getb(void* buf, int size) {
> > buf=&b[offset..offset+size]; //<-- prob here
> > }
> >
> > void read(out uint x) { getb(&x, x.sizeof); }
> > void read(out ushort x) { getb(&x, x.sizeof); }
> >
> > }
> 
> I think you meant this?
> 
> buf[0..size] = buffer[offset..offset+size];
> And also, you need to increment offset, no?
> offset += size.
> 
> I'd also recommend using a template:
> 
> void getb(T)(ref T t)
> {
>     auto size = t.sizeof;
>     auto buf = (cast(ubyte *)&t)[0..size];
>     buf[] = buffer[offset..offset+size];
>     offset += size;
> }
> 
> Now you don't need to implement each type, and you can call like this:
> int x;
> ushort y;
> getb(x); // reads 4 bytes
> getb(y); // reads 2 bytes
> 
> -Steve
> 
> 

thanks, exactly what im looking for. endianness isnt a problem at this point as im not working on a portable project.