Joseph L. Lindo

Assembly Programming

Sir Joseph LindoUniversity of the Cordilleras

Joseph L. Lindo

Set-up

Basics

Section 1

Assembly Programming

Assembly Language• Low level language

• Instruction mnemonics (Instruction Set) that have a one-to-one correspondence to machine language

•Calls functions written at the operating system level

Definition

Joseph L. Lindo

Set-up

Basics

Section 1

Assembly Programming

Assembly Applications• Business application for single platform

•Hardware device driver

•Business application for multiple platforms

•Embedded systems & computer games

Definition

Joseph L. Lindo

Set-up

Basics

Define

Assembly ProgrammingProgrammingEnvironment

Softwares Needed:

• Text Editor• Assembler• Emulator

Set-up

Joseph L. Lindo

Set-up

Basics

Define

Assembly Programming

Running Programs

Set-upSave the TEXT file with extension name .ASM

Ex. Sample.asm

Using the CMD

Compile: - ….\TASM> tasm Sample.asm

Joseph L. Lindo

Set-up

Basics

Define

Assembly Programming

Running Programs

Set-upCreate the executable file - ….\TASM> tlink Sample

Execute -….\TASM> tlink Sample

Joseph L. Lindo

Set-up

Basics

Define

Assembly Programming

Basic Elements

Basics

Joseph L. Lindo

Set-up

Basics

Define

Assembly Programming

Data Definition

Basics

A data definition statements sets aside storage in memory for variable and assign a name to the variable.

Joseph L. Lindo

Assembly Programming

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Sir Joseph LindoUniversity of the Cordilleras

Joseph L. Lindo

Assembly Programming

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Sir Joseph LindoUniversity of the Cordilleras

Joseph L. Lindo

Comparison of Assembly to HL

Assembly Language

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Assemblers

Online Task

Divide the class according to the assemblers below. Members are required to post possible knowledge about the assigned assembler.TASMMASMFASMNASMWASM

Due on February 21, 2012

Joseph L. Lindo

Assembly Link Execute Cycle

Assembly Language

SourceFile

ObjectFile

ListingFile

LinkLibrary

ExecutableFile

MapFile

Output

Step 1: text editor

Step 2:assembler

Step 3:linker

Step 4:OS loader

Joseph L. Lindo

Integer Constants

Basic Elements

Optional leading + or – signBinary, Decimal, Hexadecimal digitsCommon radix characters:

h – hexadecimald – decimalb – binary

Examples: 30d, 6Ah, 42, 1101b

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Integer Expressions

Basic Elements

Precedence Rule

Examples

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Character and String Constants

Basic Elements

Enclose character in single or double quotes'A', "x"ASCII character = 1 byte

Enclose strings in single or double quotes"ABC"'xyz'Each character occupies a single byte

Embedded quotes:'Say "Goodnight," Gracie'

Joseph L. Lindo

Reserved Words and Identifiers

Basic Elements

Reserved words cannot be used as identifiersInstruction mnemonics, directives, type attributes, operators, predefined symbols

Identifiers1-247 characters, including digitscase insensitive (by default)first character must be a letter, _, @, or $

Joseph L. Lindo

Directives

Basic Elements

Commands that are recognized and acted upon by the assembler

Not part of the Intel instruction setUsed to declare code, data areas, select memory model, declare procedures, etc.

Different assemblers have different directivesTASM != MASM, for example

Joseph L. Lindo

Directives

Basic Elements

.MODEL

It identifies the size of code and data a program could have

Syntax: <.MODEL> <memory model>

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Directives

Basic Elements

.STACK

It sets aside a block of memory to store the stack

Syntax: <.STACK> [size]

Joseph L. Lindo

Directives

Basic Elements

.DATA

It contains variables and constants definition

Syntax: <.DATA>

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Directives

Basic Elements

.CODE

It contains program’s instructions

Syntax: <.CODE>

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Memory Models

Directives

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Instructions

Basic Elements

Assembled into machine code by assemblerExecuted at runtime by the CPUMember of the Intel IA-32 instruction setParts:

LabelMnemonicOperandComment

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Labels

Instructions

Act as place markersmarks the address (offset) of code and data

Data labelmust be unique

Code labeltarget of jump and loop instructions

Follow identifier rules

Joseph L. Lindo

Mnemonics and Operands

Instructions

Instruction Mnemonics"reminder"examples: MOV, ADD, SUB, MUL, INC, DEC

Operandsconstant (immediate value)constant expressionregistermemory (data label)

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Comments

Instructions

Comments are good!explain the program's purposetricky coding techniquesapplication-specific explanations

Single-line commentsbegin with semicolon (;)

Multi-line commentsbegin with COMMENT directive and a character end with the same character

Joseph L. Lindo

Examples

Instructions

No operandsstc ; set Carry flag

One operandinc ax ; registerinc myByte ; memory

Two operandsadd bx,cx ; register, registersub myByte,25 ; memory, constantadd ax,36 * 25 ; register, expression

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Defining Variables

Data Definition

Intrinsic Data Type

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Defining Variables

Data Definition

Syntax

[name] Data Type value [,value] …

Using DUP

name Data Type size DUP (value)

Joseph L. Lindo

Assembly Programming

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Sir Joseph LindoUniversity of the Cordilleras