limitations of two pass macro processor
Answers
It is used for for identifying the macro name and performing expansion.
Features of macro processor:
Recoganized the macro definition
Save macro definition
Recoganized the macro call
Perform macro expansion
Forward reference Problem
The assembler specifies that the macro definition should occur anywhere in the program .
So there can be chances of macro call before it’s definition witch gives rise to the forwards reference problem od macro
Due to witch macro is devided into two passes
PASS 1-
Recoganize macro definition save macro definition
PASS 2-
Recoganize macro call perform macro expansion
Databases required for pass 2
In pass2 we perform recognize macro call and perform macro expansion
1.COPY FILE
It is a file it contains the out put given from PASS1
2.MNT
It is used for recognizing macro name
3.MDT
It is used to perform macro EXPANSION
4.MDTP
It is used to point to the index of MDT .
The starting index is given by MNT
5.ALA
It is used to replace the index notation by it actual value
6.ESC
It is used to contain the expanded macro call which is given to the assembler for further processing