Mail Archives: djgpp/2017/08/18/14:30:14

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Newsgroups: comp.os.msdos.djgpp
Date: Fri, 18 Aug 2017 11:13:42 -0700 (PDT)
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Subject: Re: Can I use transferbuffer temporarly a for short DMA transfer?
From: "RayeR (glaux AT centrum DOT cz) [via djgpp AT delorie DOT com]" <djgpp AT delorie DOT com>
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> "[The transfer] buffer is used for all DOS/BIOS services supported by
> DJGPP, it resides in conventional memory, and is allocated by the
> startup code."

Yes I read the DJGPP FAQ. I'm not sure what all DOS/BIOS serviuces are used by what DJGPP libc function. It seems that printf is destrying my transferbuffer data so I rather use __dpmi_allocate_dos_memory.
OK, there's no specified how this allocated memory is aligned and if the allocator prevents crossing 64kB boundary which is required by busmaster DMA - probably I have to take care myself and allocate 2-times of memory than I need and check the physical address and if it cross the boundary then dont use beginning of the buffer but higher address just behind the boundary...

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