Assembly directives and pseudo-ops, Computer Engineering

Assignment Help:

Assembly directives and pseudo-ops:

Assembly directives are which instructions that executed by the assembler at assembly time, not by the CPU at run time. They can build the assembly of the program dependent on parameters input by the programmer, so that 1 program can be assembled with different ways, may be for different type of applications. They also can be used to direct presentation of the program to make it simple for the programmer to read and maintain it.

(For instance, pseudo-ops would be used to reserve storage areas and optionally their primary contents.) The names of pseudo-ops frequently start with a dot to differentiate them from machine instructions. Some assemblers also take favor of pseudo-instructions, which produce two or more machine instructions. Symbolic assemblers permit programmers to connect arbitrary names (labels or symbols) with memory locations. Generally, every variable and constant is given a name so instructions can reference those locations by their name, therefore promoting self-documenting code.  In the executable code, the name of each subroutine is connected with its entry point, so any calls to a subroutine can use its name. In Inside the subroutines, GOTO destinations are given particular labels. Some assemblers support local symbols which are radically distinct from normal symbols (for example, the use of "10$" for a GOTO destination).

Most of the assemblers provide flexible symbol management, permit programmers to manage different type of namespaces, automatically calculate offsets within data structures, and assign labels that refer to literal values or the result of easy computations performed by the assembler. The labels can also be used to initialize variables and constants with re -locatable addresses.

Assembly languages, like most of the other computer languages, give permission to comments to be added to assembly source code that is avoided by the assembler. Good use of comments is even more significant with assembly code than with higher-level languages like c, c ++, etc., as the meaning and purpose of a sequence of instructions is difficult to decipher from the code itself.

Intelligent use of these facilities can simplify the problems of coding and maintaining low-level code. Raw assembly source code as produced by compilers or disassembles-code without any comments, data definitions, or meaningful symbols-is quite hard to read when changes must be made.


Related Discussions:- Assembly directives and pseudo-ops

An algorithm, find cos(x) and sin(x) an pseudocode (while loop

find cos(x) and sin(x) an pseudocode (while loop

Hybrid model, The hybrid models are mostly tailormade models suiting to exa...

The hybrid models are mostly tailormade models suiting to exact applications. Actually these fall in the category of mixed models. Such type of application-oriented models keep cro

How a java program compiles, How a Java program compiles? First sou...

How a Java program compiles? First source file name should be extended with .java extension. For example Myprog.java Execute javac compiler. javac compiler creates

Explain abstract class, What is an interface and what is an abstract class?...

What is an interface and what is an abstract class? Please, expand by examples of using both. Explain why?   Abstract classes are closely related to interfaces. They are classe

Explain criteria for choosing type of file organization, What criteria shou...

What criteria should be adopted for choosing type of file organization. Selecting a file organization is a design decision; therefore it must be done having in mind the achieve

Define pvm library routines, Q. Define PVM library routines? In this se...

Q. Define PVM library routines? In this segment we will give a short description of the routines in PVM 3 user library. Each PVM program must comprise the PVM header file 'pvm3

RS232C schematic diagram, Can someone provide me a scehmatic diagram of RS2...

Can someone provide me a scehmatic diagram of RS232C with explanation?

Applications of generic framework for electronic commerce, How are the appl...

How are the applications of generic framework for electronic commerce performed? To perform applications, this is essential to have Supporting Information and Organizational In

Read, i read in b.tech 3year.i can go to hadrabad becouse read of branch p...

i read in b.tech 3year.i can go to hadrabad becouse read of branch parer.why the best instituies in hadrabad in purpus gate and branch paper

What are the objectives of usb, What are the objectives of USB? a) Simp...

What are the objectives of USB? a) Simple b) Low cost c) Easy to use d) Supports wide range of data transfer characteristics e) Plug and play mode of operation

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