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

Write your array of text into file, Part I: 1. The program starts by prin...

Part I: 1. The program starts by printing your initial with an end sign ">". For example, "cjx >"; 2. Then, you can type in the following "vi filename". For example, "vi myp.c

Describe about the protection features present in ms access, If a programme...

If a programmer doesn't wish to make modifies to the document he can lock the document data and its code from more changes by changing the extension of the file system to .MDE. Cha

What are function modules, What are function modules? Function m...

What are function modules? Function modules are general-purpose library routines that are available system-wide.

What is vector processing, What is vector processing?  There is ...

What is vector processing?  There is a class of computational problems that are beyond the capabilities of a conventional computer. These problems are characterized by t

Algorithem, for calculating simple interest

for calculating simple interest

Targeting for new business, Assume you own your own small party supply and ...

Assume you own your own small party supply and rental business. You keep an Excel list of potential customers and clients who have rented or purchased from you in the past 2 years.

What is persistence, What is Persistence When you make an object, it e...

What is Persistence When you make an object, it exists for so long as you need it, but under no circumstances object exist when program terminates. While this makes sense at s

Keys, why impotant keys

why impotant keys

Instruction set architecture - assembly language, Instruction Set Architect...

Instruction Set Architecture (ISA): The Instruction Set Architecture (ISA) is the part of the processor which is noticeable to the compiler writer or programmer. The ISA serve

Illustration of code conversion, Program: A good illustration of code conve...

Program: A good illustration of code conversion: Write a program to convert a; 4-digit BCD number into its binary equivalent. BCD number is stored as a; word in memory location kno

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