Date:	Thu, 20 Aug 1998 09:42:09 +0200
From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Message-Id:	<199808200742.JAA21449@acp3bf.physik.rwth-aachen.de>
To:	GAMMELJL AT SLU DOT EDU
CC:	djgpp AT delorie DOT com
Subject:	Re: assembly language subroutines
Newsgroups:	comp.os.msdos.djgpp
Organization:	RWTH Aachen, III. physikalisches Institut B

In article <01J0S6CR6YJM94G7O9 AT SLU DOT EDU> you wrote:
[...]

Just to clear up some of the views, I've looked up the exact meaning
of 'enter' and 'leave' at home (in the TASM reference handbook).
So here it goes:

'enter $xx' is equivalent to 

	pushl %ebp
	subl $xx, %esp
	movl %esp, %ebp

and 'leave' (no arguments, at least up to i486) equals

	movl %ebp,%esp
	popl %ebp

In addition, the TASM reference mentions another form 'enter $xx,
$yy', but that seems to be too confusing to even describe it in a
sensible fashion.

The only reason for the existence of these opcodes seems to be that
they're shorter than the full sequence they substitute (--> save code
prefetch queue size). But on modern processors, (586 and up), with
their increasing emphasis on RISC rather than CISC instructions, they
got out of fashion.


--
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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