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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

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