Texas Instruments TMS320C54x, User Manual

Page: 103 / 469

Conditional Assembly Directives
4-20
4.8 Conditional Assembly Directives
Conditional assembly directives enable you to instruct the assembler to
assemble certain sections of code according to a true or false evaluation of an
expression. Two sets of directives allow you to assemble conditional blocks of
code:
-
The .if /.elseif /.else /.endif directives tell the assembler to conditionally
assemble a block of code according to the evaluation of an expression.
.if expression marks the beginning of a conditional block and
assembles code if the .if condition is true.
.elseif expression marks a block of code to be assembled if the .if
condition is false and .elseif is true.
.else marks a block of code to be assembled if the .if
condition is false.
.endif marks the end of a conditional block and termi-
nates the block.
-
The .loop /.break /.endloop directives tell the assembler to repeatedly
assemble a block of code according to the evaluation of an expression.
.loop expression marks the beginning a repeatable block of code.
.break
expression
tells the assembler to continue to repeatedly
assemble when the .break expression is false, and
to go to the code immediately after .endloop when
the expression is true.
.endloop marks the end of a repeatable block.
The assembler supports several relational operators that are useful for
conditional expressions. For more information about relational operators, see
subsection 3.9.4,
Conditional Expressions, on page 3-27.