Texas Instruments TMS320C54x, User Manual

Page: 139 / 469

.if/.elseif/.else/.endif
Assign Character Strings to Substitution Symbols
4-56
Syntax
.if well-defined expression
.elseif well-defined expression
.else
.endif
Description The following directives provide conditional assembly:
The .if directive marks the beginning of a conditional block. The well-defined
expression is a required parameter.
-
If the expression evaluates to true (nonzero), the assembler assembles
the code that follows the expression (up to a .elseif, .else, or .endif).
-
If the expression evaluates to false (0), the assembler assembles code
that follows a .elseif (if present), .else (if present), or .endif (if no .elseif or
.else is present).
The .elseif directive identifies a block of code to be assembled when the .if
expression is false (0) and the .elseif expression is true (nonzero). When the
.elseif expression is false, the assembler continues to the next .elseif (if pres-
ent), .else (if present) or .endif (if no .elseif or .else is present). The .elseif di-
rective is optional in the conditional blocks, and more than one .elseif can be
used. If an expression is false and there is no .elseif statement, the assembler
continues with the code that follows a .else (if present) or a .endif.
The .else directive identifies a block of code that the assembler assembles
when the .if expression and all .elseif expressions are false (0). This directive
is optional in the conditional block; if an expression is false and there is no .else
statement, the assembler continues with the code that follows the .endif.
The .endif directive terminates a conditional block.
The .elseif and .else directives can be used in the same conditional assembly
block and the .elseif directive can be used more than once within a conditional
assembly block.
For information about relational operators, see subsection 3.9.4,
Conditional
Expressions, on page 3-27.