What is compiler in Embedded System?

In computing system compiler is a program which convert one type language to another language which is understandable by the computer or microcontroller.  In Computer programming programs are written in some type of high level language such as C,C++ etc and computer can understand the machine(in the form of 0’s and 1’s) language. 

So a compiler compile or translate the high level programming language to low level language which is understand able by computer. In this process it also take care of spotting the error done by programmers.

Compiler Main Functions:

The main function of compiler may be divided in following process. The sequence of execution of these processes may vary from one compiler to another compiler. Main functions of compilers are as follows:

Syntax Error Analysis: In this process compiler will check the code for if code violates the certain syntax requirement. This will spot the error in the code and notify to programmer to correct them. For example if programmer forget to add semicolon “;’ after the code line complier will scan the code tell the programmer about the line number where semicolon is missing.

Variable Type Check: In this process compiler will check syntax error regarding to variable.  For example a variable is used and but not declared, variable initialize with wrong data type and variable value exceeding in accordance to type defined.

Register Allocation: Every variable we defined in the program is in symbolic form. In this process these symbols is converted to some type of numbers which defines the registers in the specific machine.

Machine Code Generation: In this process program written in the C language first converted to assembly language program according to specific architecture of machine for which program is written. After this Assembly language code is converted in to machine code language which is the binary representation of code.  This code is burned in to the program memory of machine.

Difference between Microcontroller C and Assembly

S.No.	Parameter	Assembly Language	C Language
1	System Dependency	Assembly language is a low level language. Program written in this language will be machine level language. Every Mnemonic or operand equivalent to some binary numbers. These operand codes may changes form one architecture to architecture.	C is a middle high level language. Program written in c language does not required to be system dependent. If system architecture changes then same program can run on another system with some or no changes.
2	Code Size	Program written in assembly language will have small code size.	Code size will be large with C language program.
3	Faster Execution	In assembly language we get what we have written. All programs written will directly execution without any translation. Firmware engineer choose assembly language where faster execution is necessary.	Execution of program written in C language is slower then program written in assembly language. One line written in C language may represent many lines of assembly language program.
4	Development Time	Development time of Assembly language code is large. Programmer should know the system architecture and all assembly instruction and register information of machine.	Development time in C language will be small. There are libraries to implement all the initialization and other processing tasks.
5	Portability	Program written in assembly language is not portable from one system to another system due to dependency on system architecture.	Program written in C language are Portable with no changes or with changes of header file.
6	Optimization	There will be no optimization in program written in Assembly language. Program is directly burned in to program memory without any changes.	There is optimization of code in compiling process. One line written in c language may be equivalent to 10 or more line of assembly language. Compiler has the capability to optimize the code
7	Easy Of Project Management	When program become large there will be problem in handling or managing the code.	It is easy to handle the c language program.
8	Complexity	Learning of Assembly language is hard due to dependent on machine and complexity is more.	It is easy to understand the C language code and complexity is less as compare to assembly language.