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

Signaling pvm process, Q. Signaling PVM process? int pvm_sendsig( ...

Q. Signaling PVM process? int pvm_sendsig( int tid, int signum ) Transmits a signal to other PVM process. tid is task identifier of PVM process to receive signal.

Critical capabilities for superior firm performance, What are the critical ...

What are the critical capabilities for superior firm performance in e-commerce? Three firm capabilities which are critical for superior firm performance within e-commerce are:

Computer to computer transmission of structured data, Computer to computer ...

Computer to computer transmission of structured data using standardised documentation is known as Electronic data interchange (EDI).

Describe the interpretation features of vba, VBA is licensed to Microsoft a...

VBA is licensed to Microsoft and this compatible with and only Microsoft products. Code written is compiled by an intermediate language known as P-code and this is stored in hostin

Define the example client-server implementations, Define the Example Client...

Define the Example Client-server Implementations Once you accept the client-server mindset, the process of architecting and developing applications becomes rather easy. Clearly

Define restoring method, Define restoring method? The hardware method j...

Define restoring method? The hardware method just explained is called the restoring method. The reason for this name is that the partial reminder is restored by adding the divi

Find the de broglie wavelength of electron, Q. Find the de Broglie waveleng...

Q. Find the de Broglie wavelength of electron in the fourth orbit of hydrogen atom. We know that,            λ = 2πr / n λ4 = 2πr 4 / 4  = 2π (4 2 r1) / 4  = 2 X

How does vb.net achieve polymorphism, How does VB.NET/C# achieve polymorphi...

How does VB.NET/C# achieve polymorphism?  VB.Net / C# provide polymorphism through the following mechanisms: 1. Inheritance - base class gives overridable methods which ar

Future scope of the internet, Q. Future scope of the Internet? The futu...

Q. Future scope of the Internet? The future scope of the Internet, along with the World Wide Web (born in 1990), and the commercialization of the Internet are bound to grow exp

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