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

Java, mine sweeper algorithm.

mine sweeper algorithm.

Input device used in computer system, Input device used in computer system:...

Input device used in computer system: An input device is typically a mouse or keyboard, the input device is the conduit through which data and instructions enter a computer. A

Program that will blink as led, Take the last two digits of your UTCID. Thi...

Take the last two digits of your UTCID. This is your duty cycle in percent. If your duty cycle is less than 10%, add 30 to your number. Create an assembly program that runs on t

What do you mean by stack unwinding in c++, Stack unwinding in C++ is a pro...

Stack unwinding in C++ is a process during exception handling when the destructor is known for all local objects the place where the exception was thrown and where it is caught.

Difference between absolute and relative path, What is the difference betwe...

What is the difference between absolute and relative path name of a file? Absolute path name: This is listing of the directories and files from the root directory to the i

DSP, Assignment of Analog to digital Ssignal Processing

Assignment of Analog to digital Ssignal Processing

How can you pass a struct by reference in e, How can you pass a struct by r...

How can you pass a struct by reference in e?   The question is phrased in a tricky way because passing by reference is the default and only possible way to pass structs in e. I

Determine the output waveforms for and and or gates, The voltage waveforms ...

The voltage waveforms shown in given fig. are applied at the inputs of 2-input AND and OR gates. Determine the output waveforms. Ans. The Output waveforms for AND and O

Determine a ring counter that consisting of five flip-flops, A ring counter...

A ring counter consisting of five Flip-Flops will have ? Ans. A ring counter have 5 states while consisting of Five Flip-Flops.

What is the difference between activity and sequence diagram, The following...

The following are the difference among Activity and Sequence Diagrams: A sequence diagram represents the way of processes implement in a sequence. For example, the order of op

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