Page 110 - DCAP507_SYSTEM_SOFTWARE

System Software

Notes  Macro-time variable (SET symbol) can be used to
 accumulate working values during the macro expansion
 amass the evaluation result of Boolean expression
 manage the macro-time conditional structures

 starts with "&" and that is not a macro instruction parameter
 be initialized to a value of 0
 be set by a macro processor directive, SET

 Macro-time conditional structure
 IF-ELSE-ENDIF
 WHILE-ENDW

7.2.4 Keyword Macro Parameters

 Positional parameters
 Parameters and arguments are connected as per their positions in the macro prototype
and invocation.

!

Caution The programmer must state the arguments in appropriate order.
 If an argument is to be misplaced, a null argument should be used to preserve the
proper order in macro invocation statement.

Example: Presume a macro instruction GENER has 10 possible parameters, but
in a specific invocation of the macro only the 3rd and 9th parameters are to be mentioned.
 The statement is GENER , DIRECT,,,,,,3.
 It is not appropriate if a macro has a huge number of parameters, and only anew of
these are agreed values in a classic invocation.
 Keyword parameters
 Every argument value is written with a keyword that names the corresponding
parameter.
 Arguments may emerge in any order.
 Null arguments no longer need to be used.
 If the 3rd parameter is named &TYPE and 9th parameter is named &CHANNEL, the
macro invocation would be GENER TYPE=DIRECT,CHANNEL=3.
 It is simpler to read and much less error-prone than the positional method.

Consider the Example

 Here every parameter name is followed by equal sign, which determines a keyword
parameter and a default value is mentioned for some of the parameters.

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