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From: valley@uchicago (Doug Dougherty)
Newsgroups: comp.os.msdos.programmer
Subject: Re: iret and retf
Message-ID: <valley.668976477@gsbsun>
Date: 14 Mar 91 18:47:57 GMT
References: <1991Mar14.031024.12576@msuinfo.cl.msu.edu>
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leeda@frith.egr.msu.edu (Dae Hee Lee) writes:


>When can I use retf instead of iret?
>I was told that retf discards some register in a stack.  Then, why and when can I discard any registers in a stack?
>Thank you for your help!

IRET pops 3 three words off the stack, IP, CS, flags, in that order.
(I.e., IP is @SP, CS is [SP+2], flags is [SP+4], in pseudoassembler)
So, if you use RETF instead of IRET, you will be leaving one word of
flags on the stack.  I think this is what INT 25/INT 26 do.