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Howto receive 4GB memory as one chunk, DPMI + Watcom C (Developers)

posted by DosWorld(R), 06.02.2019, 23:06


I had develop software (text editor) and I want open very huge files. My problem is - dpmi hosts does not return memory as one chunk. So, watcom memory manager use memory only from one chunk (~64mb, with causeway extender - 220mb). How to received full memory as one chunk?

My target - open 3-3.5gb text file. Now, I can open only little bit more 40mb :(
May be somebody have any advise..

As I understood, need something like virtual memory mapping. (But what is it and how prepare it?)

PS: One time I receive all memory as one chunk, but in very strange way: I compile programm for watcom "compact" memory model for dos4g-extender and run it via HX's dpmild32. I had read recomendations does not use this memory model (because library is not ready, but printf works for me!) and I dont known how to receive access to first megabyte (0000:004xx, b800:0000) in this memory model. At the same time, programm compiled for "hxdos" had 64mb chunks.

PPS: For memory size check I am use source code from Watcom Programmers Guide (I hope, many people see it).

PPPS: I had receive big speed degradation for watcom's malloc, after 500k allocated strings. I think, it will be unusable after 1m malloc's. It is looks like watcom manage memory via linked list structure. So, I want refuse using watcom malloc and switch to my own memory manager (may be he not so fast, but he remember where is stored first free memory block).


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