chapter 17 programming tools

Chapter 17Programming Tools

The Architecture of Computer Hardware and Systems Software:

An Information Technology Approach

3rd Edition, Irv Englander

John Wiley and Sons 2003

Chapter 17 Programming Tools 17-2

Programming Tools OverviewProgramming Tools Overview

EditorsEditors AssemblersAssemblers DebuggersDebuggers

CompilersCompilers LinkersLinkers LoadersLoaders InterpretersInterpreters

Integrated Development Environments (IDEs) Integrated Development Environments (IDEs) combine several of the above programming toolscombine several of the above programming tools


The Program Translation Process

Terms,terms, andmore terms!

Source

Object

Executable

Translator

Linker

Loader


Visual Basic IDE


Program Text Editors Word processors format the appearance of the text Text editors

Format the spacing between words for legibility Ideal for structured languages Text is the same font size

Examples DOS – Edit Windows – Notepad, Wordpad Unix / Linux – ed, vi, emacs

IDEs MS Visual C++, Symantec Visual Cafe


Programming Language Categories

Machine Language Binary coded instructions

Assembly Language Symbolic coded instructions

Procedural Languages procedural statements or arithmetic notation

Four-generation Languages Natural language and nonprocedural statements

Object-oriented Languages Combination of objects and procedures


Assembly Language

When to use When speed or size of program is critical Hybrid approach Hardware Drivers Can use specialized instructions

Disadvantages Inherently machine specific Architectures may become obsolete Lack of programming structure


Assemblers Binary code = machine code Hex code Assembly Language

Mnemonic names op codes Labels memory addresses Comments Symbol table Operations table Memory Relocation

Cross Assembler


What Does This Program Do?

00 IN 901 ;input three numbers and save01 STO 99 39902 IN 90103 STO 98 39804 IN 90105 STO 97 397 ;subtract number in 98 from that in 9706 SUB 98 298 ;number in 97 larger07 BRP 10 811 ;number in 98 larger, restore 9808 LDA 98 59809 BR 11 61110 LDA 97 597 ;restore 9711 STO 96 396 ;store larger of (97, 98) in 9612 SUB 99 299 ;subtract number in 99 from larger13 BRP 16 816 ;number in 96 larger14 LDA 96 599 ;number in 99 larger, restore 9915 BR 17 61716 LDA 96 596 ;restore 9617 OUT 90218 COB 000


LMC Program in Java Use instructions in a more understandable

language

static int max (int x[]){

for (i=1; i<=3; i++)x[i] = input.getint();

max_int = x[1];for (i=2; i<=3; i++)

if (x[I] > max_int)max_int = x[I];

System.output.println(max_int);}


Procedural Languages COBOL

Wordy but easier to maintain FORTRAN

Scientists and engineers BASIC Pascal

Highly structured teaching language C

high-level commands and low-level access to hardware


Object-Oriented Languages

SmallTalk C++ Java

Based on C++ Platform independent


Compilers

Translates high-level language into low-level instructions

High-level language: Source code Machine-level: Object code Changes, including bug fixes, require

recompiling


Language Components

Lexicon All legal words in the language Meaning and type

Syntax grammar rules

Semantics meaning of command


Computer Language Descriptions

Narrative Syntax (Railroad) Diagrams BNF

Backus-Naur Form Context-Free Grammar


Railroad Diagram Examples


Typical BNF Rules for Java


Parsed English Sentence


The Compilation Process

Checks for errors

Generates CPU instructions or library calls

Updates internal tables


Process of Parsing

Lexical analysis Also known as scanning Divides the string of input characters into

single elements, tokens, based on strict computer punctuation

Syntactic analysis Checks for errors in grammar rules

Semantic parsing Determines the meaning of the string


Source Code Instructions Data declarations:

Data type such as floating point, integer Data operations

Instructions that update or compute data value (lots of moving around!)

Control Structures Branches, Goto (yetch!), If-then-else, loops such as

While-do and Repeat-until Function, procedure, or subroutine calls

Receives control via a call instruction, receives and possibly modifies parameters, and returns control to the instruction after the call


Recursive Descent Parsing


Optimization Compiler analyzes code in order to

Reduce amount of code Eliminate repeated operations Reorganize parts of of the program to execute faster

and more efficiently Use computer resources more effectively

Example Move a calculation repeated within the body of a

loop that does not use any value modified by the loop

Different compilers can produce different results!


Object file or object

module

Object file

C library

Executable file

Linker

Linking


Linkers

Searches program libraries to find library routines used by the program Library: collection of pre-written functions and

subroutines made available to perform commonly required activities

Determines the memory locations that code from each module will occupy and relocates instructions by adjusting absolute references

Resolves references among files


Why Link?

Construct single executable program from multiple object code files compiled at different times

Program can be subdivided into components and parceled out to different developers

Example Main program and multiple subroutines written and

compiled by different programmers at different times


Loader

Loads binary files that have been linked into main memory

Program is ready for execution


Interpreters Translates source code instructions into

machine language and executes it one statement at a time

Disadvantages Longer to execute, particularly bad for loops Uses more memory

Advantage Faster testing and code modification

Examples of interpreted languages Java, BASIC, LISP


Interpreter vs. Compiler

Resources during execution Interpreter Compiler

Contents in memory

Interpreter/compiler Yes No

Source code Partial No

Executable code Yes Yes

CPU cycles

Translation operations Yes No

Library linking Yes No

Application program Yes Yes


Debuggers

Assembly language debuggers Source code debuggers Step through programs Check variable values

chapter 17 programming tools

Documents

proceduresassembly language

size of program

store larger

emacsidesms visual c

source codemachinelevel

lowlevel access

machine specificarchitectures

javause instructions