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

General principles of pruning, General principles of pruning: The gene...

General principles of pruning: The general principles are such that: 1. Given a node N that can be chosen by player one, thus if there is another node, X, along any path,

Cn, What is the basic requirement for establishing VLANs?

What is the basic requirement for establishing VLANs?

Ann representation - artificial intelligence, A NN Representation ANNs...

A NN Representation ANNs are skilled on AI lessons because of their inspiration from brain studies and the truth that they are applied in an AI jobs, namely machine learning.

What is an abstract data type (adt), What is an Abstract Data Type (ADT)? ...

What is an Abstract Data Type (ADT)? Abstract data types or ADTs are a mathematical specification of a set of data and the set of operations that can be done on the data. They

What is gimps native graphics file format, XCF is GIMP's "native" format. T...

XCF is GIMP's "native" format. This will preserve all information about an image, having the layers.

What is parallel loop construct, Q. What is Parallel Loop Construct? Pa...

Q. What is Parallel Loop Construct? Parallel loop construct is a shortcut for specifying parallel construct comprising one loop construct and no other statements. The syntax of

Efficiency - metrics for performance evaluation, Q. Efficiency - Metrics fo...

Q. Efficiency - Metrics for performance evaluation? The other significant metric employed for performance measurement is efficiency of parallel computer system it implies that

Define router, A router is used to Distributes information among networ...

A router is used to Distributes information among networks.

Computer Network, Write a short notes on transition from IPv4 to IPv6

Write a short notes on transition from IPv4 to IPv6

What is simd, What is SIMD? Single Instruction stream, Multiple Data st...

What is SIMD? Single Instruction stream, Multiple Data stream (SIMD) shows an organization that contains many processing units under the supervision of a common control unit. A

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