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From: dillon@CORY.BERKELEY.EDU.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: PD Assembler;Label errors!
Message-ID: <8703021853.AA28960@cory.Berkeley.EDU>
Date: Mon, 2-Mar-87 13:53:15 EST
Article-I.D.: cory.8703021853.AA28960
Posted: Mon Mar  2 13:53:15 1987
Date-Received: Tue, 3-Mar-87 22:30:26 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: University of California at Berkeley
Lines: 30


	This is what is known as a phase error.  Somewhere in your code
the assembler assumed an instruction was a certain size and then in pass2
found that it was actually larger.  Usually, the instruction in question is
a FORWARD branch.  Since the destination label isn't defined yet, the
assembler assumes the branch can be done with an 8 bit displacement.  When
pass2 rolls around, BOOM, the forward branch suddenly becomes a 16 bit
displacement (assuming the label is sufficiently far away) and you get a phase
error.  The phase error is usually detected in pass2 when a program label's
address is found to be different than in pass1.

			-Matt


In article <859@crash.CTS.COM> billk@pnet01.CTS.COM (Bill Kelly) writes:
>
>LabelOne:       movea.l         #4,a0
>                movea.l         (a0),a0
>                bra LabelTwo
>
>LabelTwo        move.l          a0,_ExecBase    ; colon on label name
>                beq NoExec                      ; purposely omitted
>
>      NoExec:   rts
>
>...this code is the kind of stuff I was writing to try to determine what in my
>LARGE file had caused the errors.   In a file as small as the one above, the
>same problems would occur.  Whenever I define *any* label, I get:
>
>***** 45  Label value changed between passes.