f78
Assemble in MRI Compatibility Mode: -M
Contents|Index|Previous|Next
Assemble
in MRI Compatibility Mode: -M
The
-M
or --mri
option selects MRI compatibility mode. This changes the syntax and pseudo-op
handling of as
to make it compatible with the ASM68K
or the ASM960
(depending upon the configured target) assembler from Microtec Research.
The
exact nature of the MRI syntax will not be documented; see the MRI manuals
for more information. The purpose of this option is to permit assembling
existing MRI assembler code using as.
The
MRI compatibility is not complete.
Certain
operations of the MRI assembler depend upon its object file format, and
can not be supported using other object file formats.
Supporting
these would require enhancing each object file format individually. These
are the following.
- global symbols in common
section
The m68k MRI assembler supports common sections which are merged by the
linker. Other object file formats do not support this. as handles common
sections by treating them as a single common symbol.
- It permits local symbols
to be defined within a common section, but it can not support global symbols,
since it has no way to describe them.
- complex relocations
The MRI assemblers support relocations against a negated section address,
and relocations which combine the start addresses of two or more sections.
These are not support by other object file formats.
- END
pseudo-op specifying start address
The MRI END
pseudo-op permits the specification of a start address. This is not supported
by other object file formats. The start address may instead be specified
using the -e
option to the linker, or in a linker script.
- IDNT,
.ident
and NAME
pseudo-ops
The MRI IDNT,
.ident
and NAME
pseudo-ops assign a module name to the output file. This is not supported
by other object file formats.
- ORG
pseudo-op
The m68k MRI ORG
pseudo-op begins an absolute section at a given address. This differs from
the usual as
.org
pseudo-op, which changes the location within the current section. Absolute
sections are not supported by other object file formats. The address of
a section may be assigned within a linker script.
There
are some other features of the MRI assembler which are not supported by
as,
typically either because they are difficult or because they seem of little
consequence. Some of these may be supported in future releases. These are
the following.
- EBCDIC strings
EBCDIC strings are not supported.
- packed binary coded decimal
Packed binary coded decimal is not supported. This means that the DC.P
and DCB.P
pseudo-ops are not supported.
- FEQU
pseudo-op
The m68k FEQU
pseudo-op is not supported.
- NOOBJ
pseudo-op
The m68k NOOBJ
pseudo-op is not supported.
- OPT
branch control options
The m68k OPT
branch control options—B,
BRS,
BRB,
BRL,
and
ffb
BRW—
are ignored. as
automatically relaxes all branches, whether forward or backward, to an
appropriate size, so these options serve no purpose.
- OPT
list control options
The following m68k OPT list control options are ignored: C,
CEX,
CL, CRE,
E,
G,
I,
M,
MEX,
MC,
MD,
X.
- other OPT
options
The following m68k OPT
options are ignored: NEST,
O,
OLD,
OP,
P,
PCO,
PCR,
PCS,
R.
- OPT
D
option is default
The m68k OPT
D
option is the default, unlike the MRI assembler. OPT
NOD
may be used to turn it off.
- XREF
pseudo-op.
The m68k XREF
pseudo-op is ignored.
- .debug
pseudo-op
The i960 .debug
pseudo-op is not supported.
- .extended
pseudo-op
The i960 .extended
pseudo-op is not supported.
- .list
pseudo-op.
The various options of the i960 .list
pseudo-op are not supported.
- .optimize
pseudo-op
The i960 .optimize
pseudo-op is not supported.
- .output
pseudo-op
The i960 .output
pseudo-op is not supported.
- .setreal
pseudo-op
The i960 .setreal
pseudo-op is not supported.
0