bobc@attctc.Dallas.TX.US (Bob Calbridge) (11/25/89)
I'm a tad confused. I think I have the concept of 'heap' and 'pointers' down but not having any experience in designing test I wouldn't be able to guarantee that my concepts would be correct. So I'm going to state my understanding of the situation and those of you who see a flaw in my thinking may feel free to correct me. (please) I'm programming in the Turbo C environment. First concept concern the 'heap'. As I see it, the 'heap' in the small and tiny models are limited in size. For the tiny model the _total_ size of program and data cannot exceed 64K, meaning that the larger the code grows the less room is available in the heap. In the small model the _total_ space for code is 64K and _total_ space for the heap is 64K less the amount of room taken up by the data reserved for the program (i.e. declared variables.) Now in the larger models I figure that the space available for the heap is all the remaining memory not used by the program, its stack and data segments. (How am I doing so far?) Now here's the stick part (if I haven't gotten stuck already.) If, in the larger models, memory is reserved using any of the *alloc functions, where any one reserved memory area is less than 64K, you would use a standard pointer declaration with no modifiers. However if the area covers more than 64K you would declare a 'huge' pointer. If the area is not using heap memory but something like video ram or extended memory you would have to declare a 'far' pointer to allow the definition of a segment in the pointer. By extension a 'huge' pointer would do the same thing but would not be necessary for sufficiently small area. The 'huge' pointer would slow up processing due to the need to normalize the segment value with the offset value. Is this all essentially correct? Did I miss anything? Are there any pitfalls that I should look out for? Please correct me on any of this as I'll come out better for the experience. Thanks, Bob -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- = I know it's petty.......... = - But I have to justify my salary! - =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=