Please can you tell me what an offset is?

[psouthan]

Hi Pete,

I realise that you are kept extremely busy anbd therefore please only reply to this if you are bored! Joking aside, if possible could you please tell me what an offset is? I see it written all the time and I am sure I might be missing out on some improvements or tweaks I could make to my FS experience, maybe not? If you don't ask you don't know!

Thanks Pete

PS: if you know of a somewhere where I can read about offsets in lay terms I would appreciate you pointing me in the direction.

Regards

Merry Christmas & thank you for all your work during the year to help make our hobby enjoyable.

Paul

[Pete Dowson]

could you please tell me what an offset is?

An "offset" is ismply the difference between one number and another -- the amount one is set off from the other.

The numbers in the context of FSUIPC represent hypothetical memory addresses, and were originally actual addresses within FS98's "GLOBALS.DLL", which is what the original FS6IPC.DLL provided access to.

So, an offset of 53 (decimal) would have then referred to a position in that DLL 53 bytes from a known "start" poiunt (actually the data linkage point inside FS98).

In FS98 data representing various things inside FS were stored at different offsets within GLOBALS.DLL. So, to access those data items programs interfacing through FS6IPC provided two values -- the offset, and a size. More than one item of data might be accessed at once, and in the extreme, back then, the whole set of FS98 data could have been read by an offset of 0 and a size of about 8192.

The offsets for specific data items have been maintained despite the demise of GLOBALS.DLL, by a lot of programming in FSUIPC, which is designed to maintain this illusion of a block of memory containing data. Thus particular offsets (normally known by their Hexadecimal value rather than decimal) still refer to specific data items and some have been identical, through FSUIPC's programming, all the way through FS98, FS2000, FS2002 , FS2004 and FSX (and some even CFS1 and CFS2 on the way).

An index to data, ordered by their offsets, is maintained in the FSUIPC SDK.

I see it written all the time and I am sure I might be missing out on some improvements or tweaks I could make to my FS experience, maybe not?

If you are a programmer, then certainly, if not then it is unlikely.

Regards

Pete