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

Computer Fundamentals, state and explain the advantages of having densely ...

state and explain the advantages of having densely packed integrated Circuits in the computer

Design issues of multi-threaded processors, Q. Design issues of Multi-threa...

Q. Design issues of Multi-threaded processors? To accomplish the maximum processor utilization in a multithreaded architecture, the subsequent design issues should be addressed

Explain about strategic planning and sensitivity training, Q. Explain about...

Q. Explain about strategic planning and sensitivity training? Formulation of business strategy with the due consideration of environmental analysis and organizational appraisal

What are the components of i-way infrastructure, What are the components of...

What are the components of I-way Infrastructure? There are three components of the I-way infrastructure: • Consumer access equipment • Local on-Ramps • Global informat

Hiring problem algorithm, Consider the Hire Assistant problem. We interview...

Consider the Hire Assistant problem. We interview n candidates and always hire the best qualified so far. Let n = 5 for our example. Find the probabilities that we hire exactly 1 t

Dbms, What is meant by concurrent execution of database transactions in a m...

What is meant by concurrent execution of database transactions in a multi user system

Describe critical directive in fortan, Q. Describe Critical Directive in FO...

Q. Describe Critical Directive in FORTAN? The critical directive permits one thread executes associated structured block. When one or more threads attain critical directive the

Use of overlapped register windows, Q. Use of Overlapped Register Windows? ...

Q. Use of Overlapped Register Windows? Register file comprises 138 registers. Let them be called by register number 0 - 137.  Diagram demonstrates the use of registers: when

Explain functions introduction, Common used functions are placed within lib...

Common used functions are placed within libraries in the SQABasic directory. Files ending with ".SBH" have the public interface they give to other libraries and scripts. Files endi

Sorting circuit along with odd-even merging circuit, Q. Sorting Circuit alo...

Q. Sorting Circuit along with Odd-Even Merging Circuit? The merge sort algorithm needs two circuits which imply that one circuit for merging and another circuit for sorting the

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