During macro expansion, the macro call statement is replaced by a sequence of assembly statements. It is important to note that inner macro is not defined until the outer macro is called. Apr 29, 2012 basic macro processor functions macro definition and expansion macro processor algorithm and data structures machine independent macro processor features concatenation of macro parameters generation of unique labels conditional macro expansion keyword macro parameters macro processor design options recursive macro expansion algorithm general. Machine independent macro processor features concatenation of macro parameters, assignment vi 42. In nasm, macros are defined with % macro and %endmacro directives. A macro represents a commonly used group of statements in the source programming language. Basic macro processor functions macro definitions and expansion, macro processor algorithm and data structures, machine independent macro processor features concatenation of macro parameters, generation of unique labels, conditional macro expansion, keyword macro parameters, macro processor design options recursive macro expansion, generalpurpose macro processors, macro. The usual reason for doing this is to avoid the overhead of a function call in simple cases, where the code is lightweight enough that function call overhead has a significant impact on performance. Furthermore, if a macro call is encountered during the expansion of a macro, whether or not that call refers to the same macro a recursive macro or to another, there must be a stack of definitions, with only the current definition being active at any time. Cpp replaces an unquoted objectlike macro name with its replacement text, and then rescans it for further macros to replace. Module iv operating systems basic operating systems functions types of operating systems user. Thus the macro processor would forgetthat it had been in middle of expanding a macro when it encountered the rdchar statement. Call within a call and definition within a definition flow chart along with one example to be discussed.
Dec 01, 2019 this video explains recursive macro expansion example explanation. Sep 24, 20 what happens if you define a recursive macro. Recursive macro expansion applying al ith f fi 4 5algorithm of fig. The message is rather cryptic but makes perfect sense. This gives the macro some of the power of a function. In the former case, macros are used to make tasks using the application less repetitive. A macro instruction is a notational convenience for the programmer. C program for the implementation of a macro processor.
System programming and operating system are important parts of a system and there are various things that could be asked about system programming and operating system viva questions system programming basically deals with writing computer programs that allow the user to interface with the hardware of the computer, which in return results in the successful execution of the system software. Ppt macro processors powerpoint presentation free to. This might seem like a silly question, but by asking it we can gain some insight on the inner working of the preprocessor. Generation of unique labels, conditional macro expansion, keyword macro parameters, macro processor design options recursive macro expansion, generalpurpose macro processors, macro processing within language translators, implementation examples masm macro processor, ansi c macro processor. Macro definition and macro expansion insystem software. Chapter 6, conditional and macro assembly lecture notes for 22c. And the macros you posted are not variadic, which means having different numbers of parameters.
Macro processorsmacro definition and call, macro expansion, nested macro calls, advanced macro facilities, design of a macro processor, case study of masm. Assemblersstructure of an assembler, design of two pass assembler, single pass assembler, cross assembler. The mapping process that instantiates transforms a macro use into a specific sequence is known as macro expansion. Macro processor designs are not directly related to the computer architecture on which it runs. Recursivemacroexpansion yet another macroexpansion system which provides an easier compiletime error handling. Nor are macros expanded first and then, after expansion, conditionals processed.
Generation of unique labels conditional macro expansion keyword macro parameters. A macro is a unit of specification for program generation through expansion. This may seem like a silly question, but you will gain some knowledge on the inner working of the preprocessor of the recursive macro expansion. For this, its its expanded body lines are simply inserted into the. Previous macro processor design cannot handle such kind of recursive macro invocation and expansion, e. May 03, 2017 mix play all mix last moment tuitions youtube macro definition ll calling a macro ll expansion of macro explained with examples in hindi duration. Definition and expansion processing algorithms along with data structures. A simple solution is to write the number 100 times in cout statement. That means, the enclosing macro must have been called, before the nested macros can be called.
If the name of the macro being replaced is found during this scan of the replacement list not including the rest of the source files preprocessing tokens, it is not replaced. Ttm is a recursive, interpretive language designed primarily for string manipulation, text editing, macro definition and expansion, and other applications generally classified as systems programming. A facility for writing macros may be provided as part of a software application or as a part of a programming language. This video explains recursive macro expansion example explanation. Source code solutions system software lab c program for the implementation of a macro. Basic macro processor functions macro definitions and expansion, macro processor algorithm and data structures, machine independent macro processor features concatenation of macro parameters, generation of unique labels, conditional macro expansion, keyword macro parameters, macro processor design options recursive macro expansion, generalpurpose macro processors, macro processing. Macro processor design options recursive macro expansion, generalpurpose macro processors, macro processing within language translators, implementation examples masm macro processor, ansi c macro processor. Once macroexpand1 has determined that a symbol names a macro, it obtains the expansion function for that macro. Ppt macro processors powerpoint presentation free to view. System software vtu notes pdf ss pdf vtu smartzworld. Onepass macro processoronepass macro processor a onepass macro processor that alternate between macro definition and macro expansion in a recursive way is able to handle recursive macro definition. Recursive macro expansion4 solutions write the macro processor in a programming language that allows recursive calls.
A selfreferential macro is one whose name appears in its definition. To write a c program for the implementation of a macro processor in cs1207 system software lab. Conditional assembly is commonly used to describe this feature. Application software provides solution to a problem. Macro bodies may also contain macro calls, and so may the bodies of those called macros, and so forth.
Most macro processors can also modify the sequence of statements generated for a macro expansion, depending on the arguments supplied in the macro invocation. It is possible to solve this problem using loop or a recursion method. This is called macro expansion or expanding the macros conditional assembly are frequently considered to be mechanisms that allow a single version of the source code for a program to be used to generate multiple versions of the. Onepass macro processor a onepass macro processor that alternate between macro definition and macro expansion in a recursive way is able to handle recursive macro definition. Recall that all macro definitions are rescanned for more macros to replace. If a macro call is seen throughout the expansion of a macro, the assembler. Describe nested and recursive macro calls and its expansion. Since macro expansion is a precompiler operation, the compiler has no access to the original macro, and the intermediate source will contain expanded code that doesnt exist in the source. A free powerpoint ppt presentation displayed as a flash slide show on id. When text contains other macros, those other macros are also expanded. This is because the expand routine is recursively called but the variable used by it e. A macro, which can be used to define macros with arbitrary names, may look as follows.
Unlike standard macro expansion, traditional macro expansion has no provision to prevent recursion. This video explains recursive macro expansionexample explanation. Basic macro processor functions macro definition and expansion macro processor algorithm and data structures machine independent macro processor features concatenation of macro parameters generation of unique labels conditional macro expansion keyword macro parameters macro processor design options recursive macro expansion algorithm general. Macro names that are embedded in quotes, either from the main file or after macro replacement, do not expand. Using macro instructions programmer can leave the mechanical details to be handled by the macro processor. When the end of the definition of rdchar was recognized, expanding would be set to false. Most macro processors can also modify the sequence of statements. System software supports operation and use of computer. Recursivemacroexpansion has the completely different expansion algorithm than common lisps macro expansion, which is based on macroexpand1 and macroexpand. Kent gordon at the california institute of technology. How to differentiate between the original statements of a program. This document is highly rated by computer science engineering cse students and has been viewed 30549 times. A different type of conditional macro expansion statement is.
Macro is a unit of specification for program generation through expansion. Recursive expansion on function macros october 1, 20 august 17, 20 nicolasbrailo the last time we talked about recursive expansion rules on cs preprocessor. Macro processor replace each macro instruction with the corresponding group of source language statements. Recursive macro expansion 3 recursive macro expansion. The user might call the above macro with the statement define macro add1 when this call is executed then the macro add1 will. Mix play all mix last moment tuitions youtube macro definition ll calling a macro ll expansion of macro explained with examples in hindi duration. Macro recursive expansion to a sequence stack overflow. A parameterized macro is a macro that is able to insert given objects into its expansion. Dec 06, 2011 macro instructions definingmacros macro definition, which itself is a sequence of instruction, can be abbreviated by using macro. However, these nested macro definitions arent valid until the enclosing macro has been expanded. Conditional macro expansion most macro processors can modify the sequence of statements generated for a macro expension, depending on the arguments supplied in the macro invocation great power and flexibility implementation is easy.
Macro definition and macro expansion insystem software answers. Print a number 100 times without using loop, recursion and. Macros and macro processors macro computer science. Cs2304 system software important questions with keys 2012 1st edition. To prevent this, the selfreference is not considered a macro. Luckily the preprocessor is smart enough not to trip up on this simple piece of code. The use of a macro name with a set of actual parameters is replaced by some code generated. The processing would proceed normally until line 50, which contains a statement invoking rdchar in addaddto,t eagu e t o t eo g a acoition, the argument from the original macro invocation rdbuff would be. C program for the implementation of a macro processor cs1207 system software laboratory aim. A macro is a sequence of instructions, assigned by a name and could be used anywhere in the program. The processing would proceed normally until line 50, which contains a statement invoking rdchar in addaddto,t eagu e t o t eo g a acoition, the argument from the original macro invocation rdbuff would be lost because the values in. Basic macro processor functions macro definitions and expansion, macro processor algorithm and data structures, machineindependent macro processor features concatenation of macro parameters, generation of unique labels, conditional macro expansion, keyword macro parameters, macro processor design options recursive. Introductioncomponents of system software, language processing activities, fundamentals of language processing, development tools.
A macro consists of a name, a set of formal parameters and a body of code. If a macro call is seen throughout the expansion of a macro, the assembler starts immediately with the expansion of the called macro. Outline an algorithm for combining a linebyline macro processor with an assembler. Feb 21, 2018 recursive macro expansion3 for easy implementation, we require that rdchar macro be defined before it is used in rdbuff macro. Keyword macro parameters, macro processor design options recursive macro expansion, generalpurpose macro processors, macro processing within language translators, implementation examples masm macro processor. Recursive macroexpansion has the completely different expansion algorithm than common lisps macro expansion, which is based on macroexpand1 and macroexpand. Restriction the definition of a macro must appear in the source program before any statements that invoke that macro. The macro processor replaces each macro instruction with the corresponding group of source language statements. As a simple example, in the c programming language, this is a typical macro that is not a parameterized macro. The procedure expand would be called recursively, thus the invocation arguments in the argtab will be overwritten. Instead, all macro expansions and conditional processing are almost always.
If the macro has parameters, they are substituted into the macro body during expansion. Compilers introduction to grammars lexical analysis and parsing. Recursive macro expansion 1 if we want to allow a macro to be invoked in a macro definition, the already presented macro processor implementation cannot be used. Pls give the program for to develop a program to implement a macro processor with recursive macro expansion. A macro system for hubot supporting macro arguments, multicommand macros, and recursive macro expansion. Assembler translates mnemonic instructions into machine code.
Macro invocation of one macro by another macro is known as macro within macro and also referred to as recursive macro call. Basic macro processor functions macro definitions and expansion. Here you can download the power system software vtu notes pdf ss pdf vtu of as per vtu syllabus. Macros macro definition and call macro expansion design of macro processor. Lex and yacc1 1 write the structure of lex with an example. Macro processor design options recursive macro expansion. A macro body may also contain further macro definitions. A macro instruction abbreviated to macro is simply a notational convenience for the programmer. The value of the variable macroexpandhook is then called as a function of three arguments. System software, 3rd edition, pearson education, 1997. Systems software syllabus for is 5 sem 2010 scheme vtu. The macro begins with the % macro directive and ends with the %endmacro directive. Explain different pseudoops used for conditional macro.
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