Page 112 - DCAP507_SYSTEM_SOFTWARE

System Software

Notes Self Assessment

Fill in the blanks:
9. Most Macro Processor permits parameters to be concatenated with other ..............................
strings.

10. .............................. in the macro body may reason "duplicate labels" problem if the macro is
invocated and expanded multiple times.
11. Macro-time variable (SET symbol) starts with ".............................. " and that is not a macro
instruction parameter.
12. Parameters and arguments are connected as per their .............................. in the macro
prototype and invocation.
13. Every .............................. value is written with a keyword that names the corresponding
parameter.
7.3 Implementation

7.3.1 Implementation of Conditional Macro Expansion (IF-ELSE-ENDIF
Structure)

 A symbol table is sustained by the microprocessor.
 This table comprises the values of all macro-time variables used.
 Entries in this table are made or customized when SET statements are processed.
 This table is utilized to look up the current value of a macro-time variable whenever
it is needed.
 The testing of the condition and looping are completed while the macro is being expanded.
 When an IF statement is encountered throughout the expansion of a macro, the specified
Boolean expression is evaluated. If value is
 TRUE
 The macro processor persists to process lines from DEFTAB until it encounters
the next ELSE or ENDIF statement.
 If ELSE is encountered, then skips to ENDIF.
 FALSE
 The macro processor omits ahead in DEFTAB until it finds the next ELSE or
ENDLF statement.

7.3.2 Implementation of Conditional Macro Expansion (WHILE ENDW
Structure)

 When an WHILE statement is encountered throughout the expansion of a macro, the
particular Boolean expression is assessed. If value is

 TRUE
 The macro processor persists to process lines from DEFTAB until it encounters
the subsequent ENDW statement.

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