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Re: Ideas for a portable Forth

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"Alex McDonald" <blog@rivadpm.com> wrote in message
news:261b0427-52d2-43bf-9ad2-9f64b2f23031@s18g2000vby.googlegroups.com...
> On Jan 18, 2:34 pm, "Rod Pemberton" <do_not_h...@noavailemail.cmm>
> wrote:
...

> > XCHG should be avoided since it's slow.
>
> XCHG reg, reg is not expensive; you mean XCHG reg, mem which is
> expensive due to the implied LOCK.

I meant XCHG reg, reg is slow because it's non-pairable (or was) ...  He
should be able to find and use other instructions which are faster in
combination.

> Just use EBP as the data stack, and manipulate it directly instead of
> XCHGing and using POP/PUSH. The instructions are longer than using POP/
> PUSH/XCHG etc, but the speed of stack access isn't compromised.

Both ESP and EBP use SS by default for all 32-bit address forms.  If you're
using ESP on SS and EBP on SS, then there is a chance that both stacks could
collide, depending on the space available and consumed and where EBP and ESP
initially point.  So, if using EBP directly, he may want a segment override
to select a different memory region.  A segment override slows execution a
hare.  If he's going to use EBP directly, he'll probably want to preference
the shorter [EBP+offset] addressing if they work effectively with his code,
instead of the longer, but more flexible, SIB encodings.


Rod Pemberton

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Ideas for a portable Forth Brad <hwfwguy@gmail.com> - 2012-01-16 07:26 -0800
  Re: Ideas for a portable Forth Tarkin <tarkin000@gmail.com> - 2012-01-16 10:32 -0800
    Re: Ideas for a portable Forth Brad <hwfwguy@gmail.com> - 2012-01-17 06:44 -0800
      Re: Ideas for a portable Forth "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-01-18 09:34 -0500
        Re: Ideas for a portable Forth Mat <dambere@web.de> - 2012-01-18 12:09 -0800
        Re: Ideas for a portable Forth Alex McDonald <blog@rivadpm.com> - 2012-01-18 14:57 -0800
          Re: Ideas for a portable Forth "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-01-19 03:06 -0500
            Re: Ideas for a portable Forth Alex McDonald <blog@rivadpm.com> - 2012-01-19 03:14 -0800
              Re: Ideas for a portable Forth "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-01-19 17:33 -0500
                Re: Ideas for a portable Forth stephenXXX@mpeforth.com (Stephen Pelc) - 2012-01-20 09:37 +0000
                Re: Ideas for a portable Forth Alex McDonald <blog@rivadpm.com> - 2012-01-20 03:02 -0800
                Re: Ideas for a portable Forth Alex McDonald <blog@rivadpm.com> - 2012-01-20 04:25 -0800
                Re: Ideas for a portable Forth Mat <dambere@web.de> - 2012-01-21 07:42 -0800
                Re: Ideas for a portable Forth "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-01-21 15:48 -0500
                Re: Ideas for a portable Forth Alex McDonald <blog@rivadpm.com> - 2012-01-21 15:01 -0800
                Re: Ideas for a portable Forth "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-01-21 21:14 -0500
  Re: Ideas for a portable Forth Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-01-16 22:42 +0000
  Re: Ideas for a portable Forth "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-01-17 07:43 -0500

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