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

Autonomous rational an agents, Autonomous Rational an Agents: In many ...

Autonomous Rational an Agents: In many cases, it is inaccurate to talk about a single program or a single robot, as the multi-purpose and multi-tasking system of hardware and

How can we set the table spaces and extent sizes, How can we set the table ...

How can we set the table spaces and extent sizes? You can state the extent sizes and the table space (physical storage area in the database) in which a transparent table is to

Illustrate about object oriented development, Illustrate about object orien...

Illustrate about object oriented development object oriented development is not direct way of system development as in this approach a holistic view of application domain is co

Visual perception problems, In AI the process of perception is studied ...

In AI the process of perception is studied as a set operations. A visual scene may be encoded by sensors and represented as matrix of intensity values. These are processed b

Replacement and substitution, Replacement and substitution: However, e...

Replacement and substitution: However, equivalences allow us to change one sentence with another without affecting the meaning, it means we know already that replacing one sid

Program in java, Write a program to display grade message according to the ...

Write a program to display grade message according to the marks

What is associative search, What is associative search? The cost of an ...

What is associative search? The cost of an associative cache is higher that the cost of a direct mapped cache due to the need to search all 128 bit tag patterns to verify wheth

Reading decision trees - artificial intelligence, Reading Decision Trees ...

Reading Decision Trees There is a link between decision tree representation and logical representations, which may be exploited to form it more easy  to understand and learned

Show list files by dir command, Q. Show list files by Dir command? The ...

Q. Show list files by Dir command? The Dir command can also be used to list files from the exacting directory. For example, the list of files present in the WORD directory in d

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