Macro Processors in Assemblers/Compilers Which tasks must a macro processor perform while handling macro definitions and invocations?
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ARecognize macro definitions and macro calls
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BStore (save) macro definitions for later expansion
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CExpand macro calls and substitute actual arguments
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DAll of the above
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ENone of the above
Answer
Correct Answer: All of the above
Explanation
Introduction / Context:Macro processors extend assembly or high-level languages by allowing parameterized text substitution. They improve code reuse and readability without runtime overhead.
Given Data / Assumptions:
- Source files may contain macro definitions and macro invocations.
- The macro processor executes at translation time.
Concept / Approach:A macro definition names a template. The macro processor must parse and store definitions, detect invocations, and on each call, expand the template with actual parameters, producing plain source for the subsequent assembler/compiler stage.
Step-by-Step Solution:Identify macro boundaries (e.g., MACRO/ENDM directives).Build a macro name table and definition table.When a call is encountered, bind formal parameters to actuals.Emit expanded text in place of the call for further translation.
Verification / Alternative check:Tools like m4 or assembler macro facilities follow this pipeline, and listings will show expanded code replacing macro calls.
Why Other Options Are Wrong:Options A, B, and C each cover part of the required pipeline; only “All of the above” is complete.Option E is incorrect because macro processing does involve these steps.
Common Pitfalls:
- Confusing macro expansion (compile-time) with function calls (run-time).
- Mishandling nested macros or recursive expansions leading to infinite loops.
- Incorrect argument substitution causing subtle bugs in generated code.
Final Answer:All of the above.