50

Chapter 8. Assembler Directives

have several conditions to check,

.elseif

may be used to avoid nesting blocks if/else within each

subsequent

.else

block.

The following variants of

.if

are also supported:

.ifdef symbol

Assembles the following section of code if the specified

symbol

has been defined. Note a symbol

which has been referenced but not yet defined is considered to be undefined.

.ifc string1,string2

Assembles the following section of code if the two strings are the same. The strings may be

optionally quoted with single quotes. If they are not quoted, the first string stops at the first

comma, and the second string stops at the end of the line. Strings which contain whitespace

should be quoted. The string comparison is case sensitive.

.ifeq absolute expression

Assembles the following section of code if the argument is zero.

.ifeqs string1,string2

Another form of

.ifc

. The strings must be quoted using double quotes.

.ifge absolute expression

Assembles the following section of code if the argument is greater than or equal to zero.

.ifgt absolute expression

Assembles the following section of code if the argument is greater than zero.

.ifle absolute expression

Assembles the following section of code if the argument is less than or equal to zero.

.iflt absolute expression

Assembles the following section of code if the argument is less than zero.

.ifnc string1,string2.

Like

.ifc

, but the sense of the test is reversed: this assembles the following section of code if

the two strings are not the same.

.ifndef symbol

.ifnotdef symbol

Assembles the following section of code if the specified

symbol

has not been defined. Both

spelling variants are equivalent. Note a symbol which has been referenced but not yet defined is

considered to be undefined.

.ifne absolute expression

Assembles the following section of code if the argument is not equal to zero (in other words, this

is equivalent to

.if

).