1.2 Language Processing Activities

• The fundamental language processing activities divided into

two parts.

1. Program generation activities

2. Program execution activities

[Prog. Generation] [Prog. Execution]

Specification Gap Execution GapApplication PL ExecutionDomain Domain Domain

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Language Processing Activities

• A program generation activity aims to generation of a

program. Source is the application domain and target is

the PL domain. It bridges specification gap.

• A program execution activity aims to execute a program

written in PL. source is PL domain and target is

execution domain. It bridges execution gap.

2

1. Program Generation

• The program generator is a software system which

accepts the specification of a program to be generated and

generates program in a the target PL.

• This activity is done by program generator domain.

Program

Specification

Program

Specification

Program

Generator

Program

Generator

Program

in target PL

Program

in target PL

ErrorsErrors

3

1. Program Generation

• The generator domain is close to the application domain, it is

easy for the designer or programmer to write the specification

of the program to be generated.

• A program generator is software that enables an individual to

create a program with less efforts and prog. Knowledge.

• A user may only be required to specify the step or rules

required for the program and not need to write and code or

less code.

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2. Program Execution

• Two popular models for program execution are:

1. Program Translation

2. Program Interpretation

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2.1 Program Translation

• The program translation model bridges the execution

gap by translating a program written in a PL called

source program(SP), into an equivalent program in the

machine language called target program(TP)

Source

Program

Source

Program

TranslatorTranslator Target

Program

Target

Program

ErrorsErrors

m/c language

program

m/c language

program

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2.1 Program Translation

• Characteristics of the program translation model are: A program must be translated before it can be executed. The translated program may be saved in file. The saved

program may be executed repeatedly. A program must be retranslated following modifications.

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2.2 Program Interpretation

• It reads the source program and stores it in its memory.

• During interpretation it takes a source statement,

determines its meaning, and performs actions like

computation and I/O which implement it.

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2.2 Program Interpretation

• In the program interpretation, the CPU use a program

counter(PC) to note the address of the next instruction to

be executed. This instruction is subjected to the

instruction execution cycle consisting following step:

1. Fetch the instruction

2. Decode the instruction to determine the operation to be

performed.

3. Execute the instruction.

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2.2 Program Interpretation

• At the end of the cycle. The PC is updated and the cycle

is repeated for the next instruction.

• Thus, the PC can indicate which statement of the source

program is to be interpreted next.

PCPC Source

Program

+

Data

Source

Program

+

Data

InterpreterInterpreter

ErrorsErrors

PCPC M.L.

Program

+

Data

M.L.

Program

+

Data

CPUCPUMemoryMemory MemoryMemory

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MCQ

• The _________ is a software system which generates a program in the target PL.

A. Program GeneratorB. Program SpecificationC. Program ExecutionD. program Interpretation

MCQ

• The _________ is a software system which generates a program in the target PL.

A. Program GeneratorB. Program SpecificationC. Program ExecutionD. program Interpretation

MCQ

• the CPU use ___________ to note the address of the next instruction to be executed.

A. program counter(PC)

B. Pretty printer

C. static checker

D. None

MCQ

• the CPU use ___________ to note the address of the next instruction to be executed.

A. program counter(PC)

B. Pretty printer

C. static checker

D. None

MCQ

• The Program generator _______ to convert _________• The _________ fetch, decode and execute instruction