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Date: Thu, 17 Jul 2014 23:31:20 -0400
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From: DJ Delorie <dj AT delorie DOT com>
To: djgpp AT delorie DOT com
In-reply-to: <82286315-4f2d-4699-8c58-97fb7bdf08cc@googlegroups.com> (message
	from Jim Michaels on Thu, 17 Jul 2014 19:53:42 -0700 (PDT))
Subject: Re: question about implementation,usage of _dosmemput*
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> an example that includes an actual variable that'w wider than 1 byte
> to put into memory would be very very helpful.

The dosmemputw example puts a "variable" (the array) which is 4,000
bytes long.  The _go32_dpmi_allocate_dos_memory() example moves
want_size bytes at a time.

> if buffer is the target as it's described, where do I put the
> source? no argument for this I can find.

The dosmemputw et al function have three different arguments.  Only
one is a pointer.  One is documented as a physical address.  The
documentation says "from the program's virtual address space" so the
pointer argument is the source, and "to MS-DOS's conventional memory
space" with the math for computing that using offset, which is the
destination.  It then says "and buffer is a pointer to somwhere
... where the data will come from."

I'm not sure how this is confusing.

>     const uint16_t key=0xb055;
> _dosmemputw(__tb+0,1,info.rm_segment*16);
> 
> where do I put the address for key?

In this case, __tb is the physical address, and &key is the virtual
address of your data.

_dosmemputw(&key, 1, __tb+0);

If you allocate *more* dos memory, you now have two physical addresses
for two buffers (the transfer buffer, __tb; and the new buffer,
address in info (seg*16+ofs)).