|Non-Confidential||PDF version||ARM DUI0473M|
|Home > Symbols, Literals, Expressions, and Operators > Assembly time substitution of variables|
You can assign a string variable to all or part of a line of assembly language code. A string variable can contain numeric and logical variables.
Use the variable with a
$ prefix in the
places where the value is to be substituted for the variable. The dollar character instructs
armasm to substitute the string into the source code line before
checking the syntax of the line. armasm faults if the substituted line is
larger than the source line limit.
Numeric and logical variables can also be substituted. The
current value of the variable is converted to a hexadecimal string
F for logical variables)
Use a dot to mark the end of the variable name if the following character would be permissible in a symbol name. You must set the contents of the variable before you can use it.
If you require a
$ that you do not want
to be substituted, use
$$. This is converted
to a single
You can include a variable with a
in a string. Substitution occurs in the same way as anywhere else.
Substitution does not occur within vertical bars, except that vertical bars within double quotes do not affect substitution.
; straightforward substitution GBLS add4ff ; add4ff SETS "ADD r4,r4,#0xFF" ; set up add4ff $add4ff.00 ; invoke add4ff ; this produces ADD r4,r4,#0xFF00 ; elaborate substitution GBLS s1 GBLS s2 GBLS fixup GBLA count ; count SETA 14 s1 SETS "a$$b$count" ; s1 now has value a$b0000000E s2 SETS "abc" fixup SETS "|xy$s2.z|" ; fixup now has value |xyabcz| |C$$code| MOV r4,#16 ; but the label here is C$$code