🚀 go-pugleaf

In article <22471@hacgate.SCG.HAC.COM> bill@solaria (Bill Neisius) writes:
>saidra@prism.CS.ORST.EDU (Raoul Said) writes:
>: 
>: 	Say I have a far pointer and I want to read a large file to it.
>: How can I do a : read(handle,far_pointer,size); when read requires a near
>: pointer?  I know I have to cast or convert or something but I've tried 
>: everything!  Thanks
>
>I don't think you can cast a far pointer to near, since the whole 'point'
>of the far pointer is to access data beyond the range of the near pointer.
You can cast a far pointer to a near, but there are two things to
take into consideration before doing so. First, you will lose the
top 16 bits of whatever value you had, and the compiler will
complain. Secondly, I don't know how motorola handles this, but on
Intel it is possible to do so, so long as the pointer is not a
normalized pointer. That way when the top sixteen get pitched, you
only loose the segment attached to the pointer, but you'd better
make real sure the offset that is left is really what you want.

Pratically speaking you're really better off, not doing that and
sticking to a more portable approach such as compiling in Large or
Huge model and letting the compiler resolve the reference for
read() with the correct model library.

>
>On the other hand, I don't see anything in the description of read() that
>says the buffer _has_ to be a near pointer...it just uses the default pointer
>type for the current memory model.  Why not just recompile
>the program with large memory model?  That way all pointers become far
>and the problem should go away....
>
>Bill Neisius
>bill@solaria.hac.com


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