210
Chapter 38. TIC54X Dependent Features
Subsyms may be defined using the
.asg
and
.eval
directives (Section 38.9 Directives, Section 38.9
Directives.
Expansion is recursive until a previously encountered symbol is seen, at which point substitution
stops.
In this example, x is replaced with SYM2; SYM2 is replaced with SYM1, and SYM1 is replaced with
x. At this point, x has already been encountered and the substitution stops.
.asg
"x",SYM1
.asg
"SYM1",SYM2
.asg
"SYM2",x
add
x,a
; final code assembled is "add
x, a"
Macro parameters are converted to subsyms; a side effect of this is the normal
as
'\ARG' dereferenc 
ing syntax is unnecessary. Subsyms defined within a macro will have global scope, unless the
.var
directive is used to identify the subsym as a local macro variable Section 38.9 Directives.
Substitution may be forced in situations where replacement might be ambiguous by placing colons on
either side of the subsym. The following code:
.eval
"10",x
LAB:X:
add
#x, a
When assembled becomes:
LAB10
add
#10, a
Smaller parts of the string assigned to a subsym may be accessed with the following syntax:
:
symbol
(
char_index
):
Evaluates to a single character string, the character at
char_index
.
:
symbol
(
start
,
length
):
Evaluates to a substring of
symbol
beginning at
start
with length
length
.
38.6. Local Labels
Local labels may be defined in two ways:
$N, where N is a decimal number between 0 and 9
LABEL?, where LABEL is any legal symbol name.
Local labels thus defined may be redefined or automatically generated. The scope of a local label is
based on when it may be undefined or reset. This happens when one of the following situations is
encountered:
.newblock directive Section 38.9 Directives
The current section is changed (.sect, .text, or .data)






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