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digitalmars.D.learn - Memory mapped IO

reply Dan Olson <zans.is.for.cans yahoo.com> writes:
I'm exploring D for embedded work as a nice alternative to C/C++ for the
32-bitters and am finding it has a nice set of features.  But, what is
the best way handle memory mapped IO?  I don't see volatile like in C.
Is writing asm {} the best way to ensure memory access?

Thanks,
Dan Olson
Jan 09 2011
parent reply "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
On Sun, 09 Jan 2011 22:44:44 -0800, Dan Olson wrote:

 I'm exploring D for embedded work as a nice alternative to C/C++ for the
 32-bitters and am finding it has a nice set of features.  But, what is
 the best way handle memory mapped IO?  I don't see volatile like in C.
 Is writing asm {} the best way to ensure memory access?
 
 Thanks,
 Dan Olson

Would std.mmfile be what you need? http://www.digitalmars.com/d/2.0/phobos/std_mmfile.html -Lars
Jan 10 2011
next sibling parent Dan Olson <zans.is.for.cans yahoo.com> writes:
"Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:

 On Sun, 09 Jan 2011 22:44:44 -0800, Dan Olson wrote:

 I'm exploring D for embedded work as a nice alternative to C/C++ for the
 32-bitters and am finding it has a nice set of features.  But, what is
 the best way handle memory mapped IO?  I don't see volatile like in C.
 Is writing asm {} the best way to ensure memory access?
 
 Thanks,
 Dan Olson

Would std.mmfile be what you need? http://www.digitalmars.com/d/2.0/phobos/std_mmfile.html -Lars

Ok, thanks. So I see that is a wrapper for mmap. So that would be good for user space code running on top of posix or win32. But... I'm more interested in the general embedded case with a small OS or no OS (just ISRs and main loop). I'm betting without volatile, asm {} is the next best thing for tickling a controllers peripheral registers? Yes/No? I searched the news groups and saw there used to be a volatile. But it looks like it was done away with because of how it was misused (like C volatile) for thread sharing. But this is different. This is just telling the compiler not to optimize away an access. -- Dan Olson
Jan 10 2011
prev sibling parent "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
On Mon, 10 Jan 2011 08:38:15 -0800, Dan Olson wrote:

 "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
 
 On Sun, 09 Jan 2011 22:44:44 -0800, Dan Olson wrote:

 I'm exploring D for embedded work as a nice alternative to C/C++ for
 the 32-bitters and am finding it has a nice set of features.  But,
 what is the best way handle memory mapped IO?  I don't see volatile
 like in C. Is writing asm {} the best way to ensure memory access?
 
 Thanks,
 Dan Olson

Would std.mmfile be what you need? http://www.digitalmars.com/d/2.0/phobos/std_mmfile.html -Lars

Ok, thanks. So I see that is a wrapper for mmap. So that would be good for user space code running on top of posix or win32. But...

Ah, I should have read your post more closely. I just saw "memory mapped IO" and latched onto that. :)
 I'm more interested in the general embedded case with a small OS or no
 OS (just ISRs and main loop).  I'm betting without volatile, asm {} is
 the next best thing for tickling a controllers peripheral registers?
 Yes/No?
 
 I searched the news groups and saw there used to be a volatile.  But it
 looks like it was done away with because of how it was misused (like C
 volatile) for thread sharing.  But this is different.  This is just
 telling the compiler not to optimize away an access.

AFAIK, that's right. The compiler does not optimise across asm {} blocks. -Lars
Jan 10 2011