Enumerate data structures used during 1-pass of assembler, Computer Engineering

Assignment Help:

Enumerate the data structures used during the first pass of the assembler. Indicate the fields of these data structures and their purpose/usage.

Three main data structures used throughout the first pass of the assembler are given below:

- LOCCTR i.e. Location counter

- OPTAB i.e. operation code table

- SYMTAB i.e. Symbol table

LOCCTR: It is Location Counter that maintains track machine addresses of symbolic tables.

  • Initialized with START.
  • Raised for all instructions
  • Pseudo Instructions are: BYTE, WORD, RESB and RESW.
  • Machine Instructions are: Fixed length (i.e. 3 bytes) for SIC, variable length for SIC/XE (looking up OPTAB).
  • Allocate the value (address) of LOCCTR to consequent symbol table.

OPTAB: In this operation table mnemonic operation code and have its machine language equivalent.

346_OPTAB.png

  OPTAB can be implemented by using hashing function for fast access.

  SYMTAB: in Symbol table symbolic label, operand and their consequent machine are keeps addresses.

656_SYMTAB.png

  • SYMTAB is dynamic, constructed throughout Pass 1:

                   a. For symbolic label, fill in address and symbol (as per to current LOCCTR).

                   b. For symbolic operand, fill into symbol and mark this as undefined. Address field will be challenged later.

  • SYMTAB can be implemented by using hashing function for fast access.

Related Discussions:- Enumerate data structures used during 1-pass of assembler

Sort, quick sort working

quick sort working

Which objects are independent transport objects, Which objects are independ...

Which objects are independent transport objects? Domains, Data elements, Tables, Technical settings for tables, Secondary indexes for transparent tables, Structures, Views, Ma

Differentiate between qa and testing, Differentiate between QA and testing....

Differentiate between QA and testing. - Quality Assurance is more a stop thing, ensuring quality in the company and thus the product rather than just testing the product for so

Other equivalences, Equivalences: In this following miscellaneous equi...

Equivalences: In this following miscellaneous equivalence rules are often useful during rewriting sessions. So there the first two allow us to completely get rid of implicatio

How to clear a datagrid on a button click, How to clear a datagrid on a but...

How to clear a datagrid on a button click? You require to Clear the DataSource of the dataGrid. So try this: dataSet1.Clear(); dataGrid1.DataSource = dataSet1.TableNam

Disadvantages of mpi, Disadvantages of MPI  Performance is restric...

Disadvantages of MPI  Performance is restricted by communication network between the nodes It can be harder to debug Needs more programming changes to go from seri

Exponential search, Exponential Search Another alternative to variable ...

Exponential Search Another alternative to variable size decrease-and-conquer search is known as exponential search. This algorithm begins searching at the beginning of the list

Explain about communication displays and matrix, Q. What is communication D...

Q. What is communication Displays and Matrix? Communication Displays Communication displays offer support in concluding frequency of communication whether congestion in me

What are the functions of virtual file system, What are the functions of vi...

What are the functions of virtual file system (VFS)? a. It splits file-system-generic operations from their implementation explaining a clean VFS interface. It allows transpare

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd