billk@crash.UUCP (03/02/87)
Has anyone used the public domain 68000 MACRO Assembler (written by
W. WESLEY HOWE)???
It seems to be very nicely put together except for the fact that I'm having
trouble defining any sorts of labels at all. I've tried all the different
ways of labeling things that the docs mention. I've made *short* files to
try to find out what's wrong. I.E:
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.
...and I get this for each label defined! Gack!
Does anyone have any idea what the (CENSORED) is going on?
Thanks,
NAME: Bill Kelly
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FONE: (619) 454-1307tim@amdcad.UUCP (03/02/87)
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. The MC68020 User's Manual states " Note: A short branch to the immediately following instruction cannot be generated, because it would result in a zero offset, which forces a word branch instruction definition." The assembler assumes in pass 1 that the displacement of the branch label can fit in an 8-bit field, and doesn't know the actual displacement until the end of pass1 (since it is a forward reference). Then in pass2, it discovers that the branch matches the above condition, and changes the displacement size to 16-bits. This causes further labels to now be off by 1 byte from pass1 to pass2, hence the error message you see. You will somehow have to force the branch to use the 16-bit displacement mode in pass1 (sorry, I don't know the syntax for your assembler.) -- Tim Olson Advanced Micro Devices tim@amdcad
dillon@CORY.BERKELEY.EDU.UUCP (03/02/87)
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.
higgin@cbmvax.UUCP (03/03/87)
In article <859@crash.CTS.COM> billk@pnet01.CTS.COM (Bill Kelly) writes:
$Has anyone used the public domain 68000 MACRO Assembler (written by
$W. WESLEY HOWE)???
$
I haven't.
$It seems to be very nicely put together except for the fact that I'm having
$trouble defining any sorts of labels at all. I've tried all the different
$ways of labeling things that the docs mention. I've made *short* files to
$try to find out what's wrong. I.E:
$
$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.
$
$...and I get this for each label defined! Gack!
$
$Does anyone have any idea what the (CENSORED) is going on?
$
$Thanks,
$
$NAME: Bill Kelly
$UUCP: {akgua, hplabs!hp-sdd, sdcsvax}!crash!pnet01!billk
$ARPA: crash!pnet01!billk@nosc
$INET: billk@pnet01.CTS.COM
$USPS: 2507 Caminito La Paz "We buy your old junk
$ La Jolla, CA 92037 and sell fine furnature..."
$FONE: (619) 454-1307
Perhaps the assembler REQUIRES that you specify whether you're doing long
or short branches. That is beq.s or beq.l, etc.
Maybe this causes errors between passes.
Paul.