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 Gap Application PL Execution Domain Domain Domain 1
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 Errors 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. 4
2. Program Execution Two popular models for program execution are: 1.Program Translation 2.Program Interpretation 5
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 Translator Target Program Target Program Errors m/c language program m/c language program 6
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. 7
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. 8
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. 9
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. PC Source Program + Data Source Program + Data Interpreter Errors PC M.L. Program + Data M.L. Program + Data CPU Memory 10
MCQ The _________ is a software system which generates a program in the target PL. A. Program Generator B. Program Specification C. Program Execution D. program Interpretation
MCQ The _________ is a software system which generates a program in the target PL. A. Program Generator B. Program Specification C. Program Execution D. 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