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 an interrupt routine to handle division by zero, Q. Write an interrup...

Q. Write an interrupt routine to handle 'division by zero'? This file can be loaded just like a COM file though makes itself permanently resident until the system is running.

Weighted harmonic mean and geometric mean, Problem Show which of the w...

Problem Show which of the weighted arithmetic mean, geometric mean or harmonic mean, you would use in each of the following case. Justify your answer in each case. (a)

Ethernet 10 base 2 is an example of which topology, Ethernet 10 Base 2 is a...

Ethernet 10 Base 2 is an example of               network topology. (A)  Bus                                           (B)  Ring (C)  Star

What is building and running mpi programs, Q. What is Building and Running ...

Q. What is Building and Running MPI Programs? MPI parallel programs are written using conventional languages such as FORTRAN and C. One or more header files like 'mpi.h' may be

What are assets in adobe premiere pro, Question: a) What is the meanin...

Question: a) What is the meaning of the term CTI in Adobe Premiere Pro? b) What are assets in Adobe Premiere Pro? c) In Adobe Premiere Pro, what is the principal diffe

Why java is called machine independent, Why Java is called Machine Independ...

Why Java is called Machine Independent? While a java program is compiled this is not converted in an executable code. Rather, this is converted in a byte code. Byte code is hig

State the concept of multiplicity, Multiplicity Multiplicity in an ass...

Multiplicity Multiplicity in an association specifies tells us about number of objects participate in a relationship. It decides the number of related objects. Multiplicity is

Explain floating point arithmetic pipelines, Floating point Arithmetic pipe...

Floating point Arithmetic pipelines Floating point calculations are the best candidates for pipelining. Take the illustration of addition of two floating point numbers. Subsequ

Explain bit slice ALUs, Bit Slice ALUs It was possible to manufacture ...

Bit Slice ALUs It was possible to manufacture smaller like 4 or 8 bits fixed point ALUs on a single IC chip. If these chips are constructed as expendable types then employing

Explain the working of linker, Explain the Working of Linker? Linker a...

Explain the Working of Linker? Linker as well called as link editor and binder. A linker is the program that combines object modules to form an executable program. Several pro

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