Xref: utzoo comp.sys.amiga:13821 comp.sys.mac:11842
Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!pasteur!ucbvax!CORY.BERKELEY.EDU!dillon
From: dillon@CORY.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga,comp.sys.mac
Subject: Re: Code Optimization
Message-ID: <8801281857.AA09606@cory.Berkeley.EDU>
Date: 28 Jan 88 18:57:58 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Lines: 31

:	In terms of floating point, things are very different here. Floating
:point operations on the Amiga are not compiled "inline", they are called.
:If you have a 68000, you can use the standard software emulation (IEEE). If
:you have the 68020, and have the 68881 or 68882 present (also detected on boot) you can simply replace the math library, and use 68881/68882 instructions
:directly. No recompiles, no changes, existing software is upward compatabible.

	What do you mean floating point operations are not compiled inline?
The *real* answer is that you can have it both ways... inline if you don't 
care about downward compatibility to a 68000, and via shared library calls
if you want downward compatibility (i.e. 68020 machines would have a different
library implementing the same functions).

:> The same agrument applies for the math co-processors, the 68881 and its new
:> sibling the 68882, which are rapidly becoming more popular on home computers.
:
:	Uh, they are? What do you have? A MacII? At a $4000.00 base price, this
:revolution is not comming soon. We are talking about some expensive hardware!

	Huh?  what kind of answer is that?  "Since I don't use it because it
costs too much nobody else uses it." ... give me a break!

:> The code optimizer, if properly written, could remove the inefficiency of
:> using primitive code on an advanced processor, simply by modifying the
:> code to take advantage of the features of the more advanced processor.
:
:	Well you lost me completely here. What advantages are not being used?

	I can think of two right off.  (1) The 68020 bit field instructions,
and (2) The 68020's extra addressing modes that allow for automatic pre
multiplication (read: array indexing in one instruction).

					-Matt