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

Introduction to computers, explain classification of computers in detail.al...

explain classification of computers in detail.also explain various application areas of computers

What is co-operative process, What is co-operative process? A process i...

What is co-operative process? A process is co-operating if it can affect or be affected by the other processes implementing in the system. Any process that share data with othe

Main drawbacks of cd-roms, Q. Main drawbacks of CD-ROMs? The main drawb...

Q. Main drawbacks of CD-ROMs? The main drawbacks of CD-ROMs are: It is read only thus can't be updated Access time is longer than that of magnetic disks. Very

What is the best way offload responsibility, What is the best way offload r...

What is the best way offload responsibility? The best way to offload responsibilities is to purchase services through a Service Provider. ISPs, customers and Service Provide

What are types of applets, There are two different parts of applets. Truste...

There are two different parts of applets. Trusted Applets and Untrusted applets. Trusted Applets are applets with predefined security and Untrusted Applets are applets without any

Garbage collector to free the memory, In .NET Compact Framework, can I free...

In .NET Compact Framework, can I free memory explicitly without waiting for garbage collector to free the memory?  Yes you can clear the memory using gc.collect method but it i

Explain the use of ssl to secure the network, Explain the use of SSL to sec...

Explain the use of SSL to secure the network.  SSL (Secure Sockets Layer) is a protocol developed by Netscape for transferring private documents by the Internet. SSL works by u

What is gdpro and magicdraw uml, What is GDPro and  MagicDraw UML GDP...

What is GDPro and  MagicDraw UML GDPro : This  is a full suite of code  management tools and UML. MagicDraw UML: UML diagrams fully support this: MagicDraw RConverter a

naming convention in local scope variables, Description Variables show ...

Description Variables show values that can be changed within a procedure or function. Local scope variables are placeholders that reside within a function- or a script-body.

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