... The Macro Processor
... Defining Macros
.macro
Defining Macros
By using macros a programmer can use a single line to insert a sequence of lines into a source program. A macro definition is headed by a .macro directive followed by the source lines. The source lines may optionally contain dummy arguments. If such arguments are used, each one is listed in the .macro directive. A macro call is the statement used by the programmer to call the macro source program. It consists of the macro name fol- lowed by the real arguments needed to replace the dummy argu- ments used in the macro. Macro expansion is the insertion of the macro source lines into the main program. Included in this insertion is the replacement of the dummy arguments by the real arguments. Macro directives provide a means to manipulate the macro ex- pansions. Only one directive is allowed per source line. Each directive may have a blank operand field or one or more operands. Legal operands differ with each directive. The macros and their associated directives are detailed in this chapter. Macro directives can replace any machine dependent mnemonic associated with a specific assembler. However, the basic assem- bler directives cannot be replaced with a macro.
.macro Directive
Format:
[label:] .macro name, dummy argument list
where: label represents an optional statement label.
name represents the user-assigned symbolic
name of the macro. This name may be
any legal symbol and may be used as a
label elsewhere in the program. The
macro name is not case sensitive,
name, NAME, or nAmE all refer to the
same macro.
, represents a legal macro separator
(comma, space, and/or tab).
dummy represents a number of legal symbols
argument that may appear anywhere in the body of
list the macro definition, even as a label.
These dummy symbols can be used elsewhere
in the program with no conflict of
definition. Multiple dummy arguments
specified in this directive may be
separated by any legal separator. The
detection of a duplicate or an illegal
symbol in a dummy argument list
terminates the scan and causes a <q>
error to be generated.
A comment may follow the dummy argument list in a .macro direc-
tive, as shown below:
.macro abs a,b ;Defines macro abs
The first statement of a macro definition must be a .macro
directive. Defining a macro with the same name as an existing
macro will generate an <m> error. The .mdelete directive should
be used to delete the previous macro definition before redefin-
ing a macro.
.endm Directive
Format:
.endm
The .endm directive should not have a label. Because the direc-
tives .irp, .irpc, and .rept may repeat more than once the label
will be defined multiple times resulting in <m> and/or <p> er-
rors.
The .endm directive may be followed by a comment field, as
shown below:
.endm ;end of macro
A comment may follow the dummy argument list in a .macro
directive, as shown below:
.macro typemsg message ;Type a message.
jsr typemsg
.word message
.endm ;End of typemsg
The final statement of every macro definition must be a .endm
directive. The .endm directive is also used to terminate inde-
finite repeat blocks and repeat blocks. A .endm directive en-
countered outside a macro definition is flagged with an
error.
.mexit Directive
Format:
.mexit
The .mexit directive may be used to terminate a macro expansion
before the end of the macro is encountered. This directive is
also legal within repeat blocks. It is most useful in nested
macros. The .mexit directive terminates the current macro as
though a .endm directive had been encountered. Using the .mexit
directive bypasses the complexities of nested conditional direc-
tives and alternate assembly paths, as shown in the following
example:
.macro altr N,A,B
.
.
.
.if eq,N ;Start conditional Block
.
.
.
.mexit ;Terminate macro expansion
.endif ;End of conditional block
.
.
.
.endm ;Normal end of macro
In an assembly where the symbol N is replaced by zero, the
.mexit directive would assemble the conditional block and ter-
minate the macro expansion. When macros are nested, a .mexit
directive causes an exit to the next higher level of macro ex-
pansion. A .mexit directive encountered outside a macro defini-
tion is flagged with an <n> error.
Calling Macros
Format:
[label:] name real arguments
where: label represents an optional statement label.
name represents the name of the macro, as
specified in the macro definition.
real represent symbolic arguments which
arguments replace the dummy arguments listed
in the .macro definition. When
multiple arguments occur, they are
separated by any legal separator.
Arguments to the macro call are
treated as character strings, their
usage is determined by the macro
definition.
A macro definition must be established by means of the .macro
directive before the macro can be called and expanded within the
source program.
When a macro name is the same as a user label, the appearance
of the symbol in the operator field designates the symbol as a
macro call; the appearance of the symbol in the operand field
designates it as a label, as shown below:
LESS: mov @r0,r1 ;LESS is a label
.
.
.
bra LESS ;LESS is considered a label
.
.
.
LESS sym1,sym2 ;LESS is a macro call
Arguments In Macro Definitions and Macro Calls
Multiple arguments within a macro must be separated by one of
the legal separating characters (comma, space, and/or tab).
Macro definition arguments (dummy) and macro call arguments
(real) maintain a strict positional relationship. That is, the
first real argument in a macro call corresponds with the first
dummy argument in the macro definition.
For example, the following macro definition and its asso-
ciated macro call contain multiple arguments:
.macro new a,b,c
.
.
.
new phi,sig,^/C1,C2/
Arguments which themselves contain separating characters must be
enclosed within the delimiter construct ^/ / where the
character '/' may be any character not in the argument string.
For example, the macro call:
new ^/exg x,y/,#44,ij
causes the entire expression
exg x,y
to replace all occurrences of the symbol a in the macro defini-
tion. Real arguments with a macro call are considered to be
character strings and are treated as a single entity during
macro expansion.
The up-arrow (^) construction also allows another up-arrow
construction to be passed as part of the argument. This con-
struction, for example, could have been used in the above macro
call, as follows:
new ^!^/exg x,y/!,#44,ij
causing the entire string ^/exg x,y/ to be passed as an argu-
ment.
Macro Nesting
Macro nesting occurs where the expansion of one macro in-
cludes a call to another macro. The depth of nesting is arbi-
trarily limited to 20.
To pass an argument containing legal argument delimiters to
nested macros, enclose the argument in the macro definition
within an up-arrow construction, as shown in the coding example
below. This extra set of delimiters for each level of nesting
is required in the macro definition, not the in the macro call.
.macro level1 dum1,dum2
level2 ^/dum1/
level2 ^/dum2/
.endm
.macro level2 dum3
dum3
add #10,z
push z
.endm
A call to the level1 macro, as shown below, for example:
level1 ^/leaz 0,x/,^/tfr x,z/
causes the following macro expansion to occur:
leaz 0,x
add #10,z
push z
tfr x,z
add #10,z
push z
When macro definitions are nested, the inner definition cannot
be called until the outer macro has been called and expanded.
For example, in the following code:
.macro lv1 a,b
.
.
.
.macro lv2 c
.
.
.
.endm
.endm
the lv2 macro cannot be called and expanded until the lv1 macro
has been expanded. Likewise, any macro defined within the lv2
macro definition cannot be called and expanded until lv2 has
also been expanded.
Special Characters in Macro Arguments
If an argument does not contain spaces, tabs, or commas it
may include special characters without enclosing them in a
delimited construction. For example:
.macro push arg
mov arg,-(sp)
.endm
push x+3(%2)
causes the following code to be generated:
mov x+3(%2),-(sp)
Passing Numerical Arguments as Symbols
If the unary operator backslash (\) precedes an argument, the
macro treats the argument as a numeric value in the current pro-
gram radix. The ascii characters representing this value are
inserted in the macro expansion, and their function is defined
in the context of the resulting code, as shown in the following
example:
.macro inc a,b
con a,\b
b = b + 1
.endm
.macro con a,b
a'b: .word 4
.endm
...
c = 0 ;Initialize
inc x,c
The above macro call (inc) would thus expand to:
x0: .word 4
In this expanded code, the label x0: results from the con-
catenation of two real arguments. The single quote (')
character in the label a'b: concatenates the real argument x
and 0 as they are passed during the expansion of the macro.
This type of argument construction is described in more detail
in a following section.
A subsequent call to the same macro would generate the fol-
lowing code:
x1: .word 4
and so on, for later calls. The two macro definitions are
necessary because the symbol associated with the dummy argument
b (that is, symbol c) cannot be updated in the con macro defini-
tion, because the character 0 has replaced c in the argument
string (inc x,c). In the con macro definition, the number
passed is treated as a string argument. (Where the value of the
real argument is 0, only a single 0 character is passed to the
macro expansion.
Number of Arguments in Macro Calls
A macro can be defined with or without arguments. If more
arguments appear in the macro call than in the macro definition,
a <q> error is generated. If fewer arguments appear in the
macro call than in the macro definition, missing arguments are
assumed to be null values. The conditional directives .if b and
.if nb can be used within the macro to detect missing arguments.
The number of arguments can be determined using the .narg direc-
tive.
Creating Local Symbols Automatically
A label is often required in an expanded macro. In the con-
ventional macro facilities thus far described, a label must be
explicitly specified as an argument with each macro call. The
user must be careful in issuing subsequent calls to the same
macro in order avoid duplicating labels. This concern can be
eliminated through a feature of the ASxxxx macro facility that
creates a unique symbol where a label is required in an expanded
macro.
ASxxxx allows temporary symbols of the form n$, where n is a
decimal integer. Automatically created symbols are created in
numerical order beginning at 10000$.
The automatic generation of local symbols is invoked on each
call of a macro whose definition contains a dummy argument pre-
ceded by the question mark (?) character, as shown in the macro
definition below:
.macro beta a,?b ;dummy argument b with ?
tst a
beq b
add #5,a
b:
.endm
A local symbol is created automatically only when a real ar-
gument of the macro call is either null or missing, as shown in
Example 1 below. If the real argument is specified in the macro
call, however, generation of the local symbol is inhibited and
normal argument replacement occurs, as shown in Example 2 below.
(Examples 1 and 2 are both expansions of the beta macro defined
above.)
Example 1: Create a Local Symbol for the Missing Argument
beta flag ;Second argument is missing.
tst flag
beq 10000$ ;Local symbol is created.
add #5,flag
10000$:
Example 2: Do Not Create a Local Symbol
beta r3,xyz
tst r3
beq xyz
add #5,r3
xyz:
Automatically created local symbols resulting from the expan-
sion of a macro, as described above, do not establish a local
symbol block in their own right.
When a macro has several arguments earmarked for automatic
local symbol generation, substituting a specific label for one
such argument risks assembly errors because the arguments are
constructed at the point of macro invocation. Therefor, the ap-
pearance of a label in the macro expansion will create a new lo-
cal symbol block. The new local symbol block could leave local
symbol references in the previous block and their symbol defini-
tions in the new one, causing error codes in the assembly list-
ing. Furthermore a later macro expansion that creates local
symbols in the new block may duplicate one of the symbols in
question, causing an additional error code <p> in the assembly
listing.
Keyword Arguments
Format:
name=string
where: name represents the dummy argument
string represents the real symbolic argument
The keyword argument may not contain embedded argument separa-
tors unless delimited as described earlier.
Macros may be defined with, and/or called with, keyword argu-
ments. When a keyword argument appears in the dummy argument
list of a macro definition, the specified string becomes the
default real argument at macro call. When a keyword argument
appears in the real argument list of a macro call, however, the
specified string becomes the real argument for the dummy argu-
ment that matches the specified name, whether or not the dummy
argument was defined with a keyword. If a match fails, a 'q'
error will be reported. If it is desired to pass a non-matching
argument of the keyword style then the argument must be
delimited.
A keyword argument may be specified anywhere in the argument
list of a macro definition and is part of the positional order-
ing of macro arguments. A keyword argument may also be speci-
fied anywhere in the real argument list of a macro call, but in
this case, does not effect the positional ordering of the argu-
ments.
1 .list (me)
2
3 ; MACRO With Dummy Arguments
4
5 .macro TBL name dev="NL",blk=0,flg=3
6 .word blk
7 .word flg
8 'name: .asciz dev
9 .even
10 .endm
11
12 ; Invoke Multiple Times
13
14 TBL NL
0000 00 00 6 .word 0
0002 00 03 7 .word 3
0004 4E 4C 00 8 NL: .asciz "NL"
0008 9 .even
15
16 TBL DY dev="DY0"
0008 00 00 6 .word 0
000A 00 03 7 .word 3
000C 44 59 30 00 8 DY: .asciz "DY0"
0010 9 .even
17
18 TBL RL dev="RL3",blk=20.
0010 00 14 6 .word 20.
0012 00 03 7 .word 3
0014 52 4C 33 00 8 RL: .asciz "RL3"
0018 9 .even
19
20 TBL DU dev="DU1",blk=1,flg=7
0018 00 01 6 .word 1
001A 00 07 7 .word 7
001C 44 55 31 00 8 DU: .asciz "DU1"
0020 9 .even
21
Concatenation of Macro Arguments
The apostrophe or single quote character (') operates as a
legal delimiting character in macro definitions. A single quote
that precedes and/or follows a dummy argument in a macro defini-
tion is removed, and the substitution of the real argument oc-
curs at that point. For example, in the following statements:
.macro def A,B,C
A'B: asciz "C"
.byte ''A,''B
.endm
when the macro def is called through the statement:
def x,y,^/V05.00/
it is expanded, as follows:
xy: asciz "V05.00"
.byte 'x,'y
In expanding the first line, the scan for the first argument
terminates upon finding the first apostrophe (') character.
Since A is a dummy argument, the apostrophe (') is removed. The
scan then resumes with B; B is also noted as another dummy ar-
gument. The two real arguments x and y are then concatenated to
form the label xy:. The third dummy argument is noted in the
operand field of the .asciz directive, causing the real argument
V05.00 to be substituted in this field.
When evaluating the arguments of the .byte directive during
expansion of the second line, the scan begins with the first
apostrophe (') character. Since it is neither preceded nor fol-
lowed by a dummy argument, this apostrophe remains in the macro
expansion. The scan then encounters the second apostrophe,
which is followed by a dummy argument and is therefor discarded.
The scan of argument A is terminated upon encountering the comma
(,). The third apostrophe is neither preceded nor followed by a
dummy argument and again remains in the macro expansion. The
fourth (and last) apostrophe is followed by another dummy argu-
ment and is likewise discarded. (Four apostrophe (') characters
were necessary in the macro definition to generate two apos-
trophe (') characters in the macro expansion.)
Macro Attribute Directives
The ASxxxx assemblers have four directives that allow the user to determine certain attributes of macro arguments: .narg, .nchr, .ntyp, and .nval. The use of these directives permits selective modifications of a macro expansion, depending on the nature of the arguments being passed. These directives are described below.
.narg Directive
Format:
[label:] .narg symbol
where: label represents an optional statement label.
symbol represents any legal symbol. This symbol
is equated to the number of arguments in
the macro call currently being expanded.
If a symbol is not specified, the .narg
directive is flagged with a <q> error.
The .narg directive is used to determine the number of arguments
in the macro call currently being expanded. Hence, the .narg
directive can appear only within a macro definition; if it ap-
pears elsewhere, an <n> error is generated.
The argument count includes null arguments as shown in the
following:
.macro pack A,B,C
.narg cnt
.
.
.
.endm
pack arg1,,arg3
pack arg1
When the first macro pack is invoked .narg will assign a value
of three (3) to the number of arguments cnt, which includes the
empty argument. The second invocation of macro pack has only a
single argument specified and .narg will assign a value of one
(1) to cnt.
.nchr Directive
Format:
[label:] .nchr symbol,string
where: label represents an optional statement label.
symbol represents any legal symbol. This symbol
is equated to the number of characters in
the string of the macro call currently
being expanded. If a symbol is not
specified, the .nchr directive is
flagged with a <q> error.
, represents any legal separator (comma,
space, and/or tab).
string represents a string of printable 7-bit
ascii characters. If the character
string contains a legal separator
(comma, space and/or tab) the whole
string must be delimited using the
up-arrow (^) construct ^/ /.
If the delimiting characters do not
match or if the ending delimiter
cannot be detected because of a
syntactical error in the character
string, the .nchr directive reports
a <q> error.
The .nchr directive, which can appear anywhere in an ASxxxx pro-
gram, is used to determine the number of characters in a speci-
fied character string. This directive is useful in calculating
the length of macro arguments.
.ntyp Directive
Format:
[label:] .ntyp symbol,arg
where: label represents an optional statement label.
symbol represents any legal symbol. The symbol
is made absolute and equated to 0 if
arg is an absolute value or a non
relocatable symbol. The symbol is made
absolute and equated to 1 if arg is a
relocatable symbol. If a symbol is not
specified then the .ntyp directive is
flagged with a <q> error.
, represents any legal separator (comma,
space, and/or tab).
arg represents any legal expression or
symbol. If arg is not specified
then the .ntyp directive is flagged
with a <q> error.
The .ntyp directive, which can appear anywhere in an ASxxxx pro-
gram, is used to determine the symbol or expression type as ab-
solute (0) or relocatable (1).
.nval Directive
Format:
[label:] .nval symbol,arg
where: label represents an optional statement label.
symbol represents any legal symbol. The symbol
is equated to the value of arg and made
absolute. If a symbol is not specified
then the .nval directive is flagged
with a <q> error.
, represents any legal separator (comma,
space, and/or tab).
arg represents any legal expression or
symbol. If arg is not specified
then the .nval directive is flagged
with a <q> error.
The .nval directive, which can appear anywhere in an ASxxxx pro-
gram, is used to determine the value of arg and make the result
an absolute value.
Indefinite Repeat Block Directives
An indefinite repeat block is similar to a macro definition
with only one dummy argument. At each expansion of the inde-
finite repeat range, this dummy argument is replaced with suc-
cessive elements of a real argument list. Since the repeat
directive and its associated range are coded in-line within the
source program, this type of macro definition and expansion does
not require calling the macro by name, as required in the expan-
sion of the conventional macros previously described.
An indefinite repeat block can appear within or outside
another macro definition, indefinite repeat block, or repeat
block. The rules specifying indefinite repeat block arguments
are the same as for specifying macro arguments.
.irp Directive
Format:
[label:] .irp sym,argument_list
.
.
(range of indefinite repeat block)
.
.
.endm
where: label represents an optional statement label.
sym represents a dummy argument that is
replaced with successive real arguments
from the argument list. If the dummy
argument is not specified, the .irp
directive is flagged with a <q> error.
, represents any legal separator (comma,
space, and/or tab).
argument_list represents a list of real arguments
that are to be used in the expansion
of the indefinite repeat range. A real
argument may consist of one or more
7-bit ascii characters; multiple
arguments must be separated by any
legal separator (comma, space, and/or
tab). If an argument must contain
a legal separator then the up-arrow
(_^) construct is require for that
argument. If no real arguments are
specified, no action is taken.
range represents the block of code to be
repeated once for each occurrence of
a real argument in the list. The
range may contain other macro
definitions, repeat ranges and/or
the .mexit directive.
.endm indicates the end of the indefinite
repeat block range.
The .irp directive is used to replace a dummy argument with suc-
cessive real arguments specified in an argument list. This
replacement process occurs during the expansion of an indefinite
repeat block range.
.irpc Directive
Format:
[label:] .irpc sym,string
.
.
(range of indefinite repeat block)
.
.
.endm
where: label represents an optional statement label.
sym represents a dummy argument that is
replaced with successive real characters
from the argument string. If the dummy
argument is not specified, the .irpc
directive is flagged with a <q> error.
, represents any legal separator (comma,
space, and/or tab).
string represents a list of 7-bit ascii
characters. If the string contains
legal separator characters (comma,
space, and/or tab) then the up-arrow
(_^) construct must delimit the string.
range represents the block of code to be
repeated once for each occurrence of
a real argument in the list. The
range may contain other macro
definitions, repeat ranges and/or
the .mexit directive.
.endm indicates the end of the indefinite
repeat block range.
The .irpc directive is available to permit single character sub-
stition. On each iteration of the indefinite repeat range, the
dummy argument is replaced with successive characters in the
specified string.
Repeat Block Directive
A repeat block is similar to a macro definition with only one
argument. The argument specifies the number of times the repeat
block is inserted into the assembly stream. Since the repeat
directive and its associated range are coded in-line within the
source program, this type of macro definition and expansion does
not require calling the macro by name, as required in the expan-
sion of the conventional macros previously described.
A repeat block can appear within or outside another macro de-
finition, indefinite repeat block, or repeat block.
.rept Directive
Format:
[label:] .rept exp
.
.
(range of repeat block)
.
.
.endm
where: label represents an optional statement label.
exp represents any legal expression.
This value controls the number of
times the block of code is to be assembled
within the program. When the expression
value is less than or equal to zero (0),
the repeat block is not assembled. If
this value is not an absolute value, the
.rept directive is flagged with an <r>
error.
range represents the block of code to be
repeated. The range may contain other
macro definitions, repeat ranges and/or
the .mexit directive.
.endm indicates the end of the repeat block
range.
The .rept directive is used to duplicate a block of code, a
certain number of times, in line with other source code.
Macro Deletion Directive
The .mdelete directive deletes the definitions of the
specified macro(s).
.mdelete Directive
Format:
.mdelete name1,name2,...,namen
where: name1, represent legal macro names. When multiple
name2, names are specified, they are separated
..., by any legal separator (comma, space, and/or
namen tab).
Macro Invocation Details
The invocation of a macro, indefinite repeat block, or repeat
block has specific implications for .if-.else-.endif constructs
and for .list-.nlist directives.
At the point a macro, indefinite repeat block, or repeat
block is called the following occurs:
1) The initial .if-.else-.endif
state is saved.
2) The initial .list-.nlist
state is saved.
3) The macro, indefinite repeat block,
or repeat block is inserted into the
assembler source code stream. All
argument substitution is performed
at this point.
When the macro completes and after each pass through an inde-
finite repeat block or repeat block the .if-.else-.endif and
.list-.nlist state is reset to the initial state.
The reset of the .if-.else-.endif state means that the invo-
cation of a macro, indefinite repeat block, or repeat block can-
not change the .if-.else-.endif state of the calling code. For
example the following code does not change the .if-.else-.endif
condition at macro completion:
.macro fnc A
.if nb,^!A!
...
.list (meb)
.mexit
.else
...
.nlist
.mexit
.endif
.endm
code: fnc
Within the macro the .if condition becomes false but the con-
dition is not propagated outside the macro.
Similarly, when the .list-.nlist state is changed within a
macro the change is not propagated outside the macro.
The normal .if-.else-.endif processing verifies that every
.if has a corresponding .endif. When a macro, indefinite repeat
block, or repeat block terminates by using the .mexit directive
the .if-.endif checking is bypassed because all source lines
between the .mexit and .endm directives are skipped.
Controlling Macro Listings
The basic .list directive enables listing of all fields in the assembler listing and clears the 'me', 'meb' and 'mel' op- tions. When a macro is entered the listing is by default inhibited unless the 'me' (enable listing), 'meb' (list only binary and location), or 'mel' (enable listing forcing binary and location) options have been specified. The 'me' option simply enables any previously set listing options. The 'meb' option clears all listing options and sets the 'bin' and 'loc' options. The 'mel' option enables the previously set listing options and forces the 'bin' and 'loc' options. If no listing options have been set then a list 'me' option will not cause any listing. Within a macro the .list/.nlist directives can set or clear any of the listing options but listing will only occur when the 'me' option is set.
Building a Macro Library
Using the macro facilities of the ASxxxx assemblers a simple
macro library can be built. The macro library is built by com-
bining individual macros, sets of macros, or include file direc-
tives into a single file. Each macro entity is enclosed within
a .if/.endif block that selects the desired macro definitions.
The selection of specific macros to be imported into a pro-
gram is performed by three macros, .mlib, .mcall, and .mload,
contained in the file mlib.def.
.mlib Macro Directive
Format:
.mlib file
where: file represents the macro library file name.
If the file name does not include a path
then the path of the current assembly
file is used. If the file name (and/or
path) contains white space then the
path/name must be delimited with the
up-arrow (^) construct ^/ /.
The .mlib directive defines two macros, .mcall and .mload, which
when invoked will read a file, importing specific macro defini-
tions. Any previous .mcall and/or .mload directives will be
deleted before the new .mcall and .mload directives are defined.
The .mload directive is an internal directive which simply
includes the macro library file with the listing disabled.
The following is the mlib.def file which defines the macros
.mlib, .mcall, and .mload.
;************************************************
;* *
;* A simple Macro Library Implementation *
;* *
;* December 2008 *
;* *
;************************************************
.macro .mlib FileName
.if b,^!FileName!
.error 1 ; File Name Required
.mexit
.endif
.mdelete .mcall
.macro .mcall a,b,c,d,e,f,g,h
.irp sym ^!a!,^!b!,^!c!,^!d!,^!e!,^!f!,^!g!,^!h!
.iif nb,^!sym! .define .$$.'sym
.endm
.mload
.irp sym ^!a!,^!b!,^!c!,^!d!,^!e!,^!f!,^!g!,^!h!
.if nb,^!sym!
.iif ndef,sym'.$$. .error 1 ; macro not found
.undefine .$$.'sym
.undefine sym'.$$.
.endif
.endm
.endm ;.mcall
.mdelete .mload
.macro .mload
.nlist
.include ^!FileName!
.list
.endm ;.mload
.endm ;.mlib
.mcall Macro Directive
Format:
.mcall macro1,macro2,...,macro8
where:
macro1, represents from 1 to 8 macro library
macro2, references to a macro definition or
..., set of macro definitions included in
macro8 the file specified with the .mlib macro.
As can be seen from the macro definition of .mlib and .mcall
shown above, when .mcall is invoked temporary symbols are de-
fined for each macro or macro set that is to be imported. The
macro .mload is then invoked to load the macro library file
specified in the call to .mlib.
For example, when the following macros are invoked:
.mlib crossasm.sml ; Cross Assembler Macros
.mcall M6809 ; M6809 Macro Group
The .mlib macro defines the .mload macro to access the system
macro file crossasm.sml. Invoking the .mcall macro creates a
temporary symbol, '.$$.M6809', and then invokes the macro .mload
to import the system macro file crossasm.sml. The file cros-
sasm.sml contains conditional statements that define the re-
quired macros and creates a temporary symbol 'M6809.$$.' to
indicate the macro group was found. If the macro is not found
an error message is generated.
The following is a small portion of the crossasm.sml system
macro file which shows the M6809 macro group:
.title Cross Assembler Macro Library
; This MACRO Library is Case Insensitive.
;
...
; Macro Based 6809 Cross Assembler
.$.SML.$. =: 0
.if idn a,A
.iif def,.$$.m6809 .$.SML.$. = -1
.else
.iif def,.$$.m6809 .$.SML.$. = -1
.iif def,.$$.M6809 .$.SML.$. = 1
.endif
.iif lt,.$.SML.$. .define m6809.$$.
.iif gt,.$.SML.$. .define M6809.$$.
.iif ne,.$.SML.$. .include "m6809.mac"
...
Example Macro Cross Assemblers
The 'ascheck' subdirectory 'macroasm' contains 7 assemblers
written using only the general macro processing facility of the
ASxxxx assemblers:
i8085.mac - 8085 Microprocessor
m6800.mac - 6800 Microprocessor
m6801.mac - 6801 Microprocessor
m6804.mac - 6804 Microprocessor
m6805.mac - 6805 Microprocessor
m6809.mac - 6809 Microprocessor
s2650.mac - 2650 Microprocessor
These absolute macro cross assemblers are included to il-
lustrate the functionality of the general macro processing
facility of the ASxxxx assemblers. In general they are useful
examples of actual macro implementations.
... Exit the ASxxxx Documentation
... Home Page