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

What is the difference between swapping and paging, What is the difference ...

What is the difference between Swapping and Paging? Swapping: Entire process is moved from the swap device to the major memory for implementation. Process size must be less t

Explain the following the address instruction, Explain the following the ad...

Explain the following the address instruction?  Three-address instruction-it can be represented as add a,b,c Two-address instruction-it can be shown as Add a,b

Solve out linear equations, Assume that you have been asked to solve proble...

Assume that you have been asked to solve problem with exact area constraints, the area error being no more than 1% for each department. What are the linear equations you would nee

State the use parameters and parameter definition modules, State the Use pa...

State the Use parameters and parameter definition modules. Parameters aren't preprocessor definitions and they have scope (for example parameters are associated with specific

Exception handling and recursion, In the previous assignment, you implement...

In the previous assignment, you implemented a stack and a list that both inherited from the abstract class ArrayIntCollection. In this task you are supposed to extend that implemen

Disadvantages of address translation, Disadvantages of Address translation:...

Disadvantages of Address translation: Disadvantages are following: A program that is too large to be held in a part needs some special design, that called overlay

Write an algorithm to outline the macro-expansion, Write an algorithm to ou...

Write an algorithm to outline the macro-expansion using macro-expansion counter. The flow of control throughout macro expansion can be implemented by using a MEC that is macro-

Define process for swapping into memory from the swap device, What are the ...

What are the criteria for choosing a process for swapping into memory from the swap device? The resident time of the processes in the change device, the priority of the process

Displays a format of floating-point number, Q. Displays a format of floatin...

Q. Displays a format of floating-point number? A floating binary number +1010.001 in a 16-bit register is able to be represented in normalised form (presuming 6 bits for expone

Illustrate logical data processing instructions, Q. Illustrate logical Data...

Q. Illustrate logical Data Processing Instructions? AND, OR, NOT, XOR operate on binary data stored in registers. For illustration if two registers comprises data:   R1 = 10

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