Tajamul21/ARM-Cross-Compilation-and-Tracing-using-Qemu-Tool

ARM cross compiler Cross compilation is the process of compiling code for one computer system also known as the target on a different system, called the host. A cross compiler is a type of compiler, that generates machine code targeted to run on a system different than the one generating it. Like we used arm cross compiler to convert from X86 processor to ARM. The Process of creating executable code for different machines is called retargeting. The cross compiler is also called as retargetable compiler. We have used GNU GCC cross compiler. A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a X86 processor but generates code that runs on ARM Processor is a cross compiler. A cross compiler is necessary to compile code for multiple platforms from one development host. Direct compilation on the target platform might be infeasible, for example on X86 using .o file , because those systems contain no operating system. In generalization, one computer runs multiple operating systems and a cross compiler could generate an executable for each of them from one main source. Cross compilers are distinct from source-to-source compilers. A cross compiler is for cross-platform software development of machine code, while a source-to-source compiler translates from one programming language to another in text code. Both are programming tools. The GNU Arm Embedded Toolchain is a ready-to-use, open-source suite of tools for C(As in our case), C++ and assembly programming. The GNU Arm Embedded Toolchain targets the 32-bit Arm Cortex-A, Arm Cortex-M, and Arm Cortex-R processor families.

ARM cross compiler Cross-compilation is the process of compiling code for one computer system (also known as the target) on a different system, called the host. A cross compiler is a type of compiler, that generates machine code targeted to run on a system different than the one genrating it.Like we used arm cross compiler to convert from X86 processsor to ARM. The Process of creating executable code for different machines is called retargeting.The cross compiler is also called as retargetable compiler.We have usesd GNU GCC cross compiler. A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a X86 processor but generates code that runs on ARM Processor is a cross compiler.

1.Visit the link :https : //www.acmesystems.it/arm9toolchain 2.As I am using an Arietta, open the terminal of ubuntu(by crtl+alt+t) write: sudoapt−getinstallgcc−arm−linux−gnueabig++−arm−linux−gnueabi 3.After writing the above code, package will start downloading. 4.You are ready to use ARM cross compile

Program Tracing

For each line of the program, explaining each line of assembly code. 1.The push instruction at the beginning of this function: Pushes the return address, the value contained in the lr register, onto the stack,the value con�tained in the fp register, onto the stack. Updates the sp to show that two 32-bit values have been pushed onto the top of the stack. 2.This instruction doesn’t set fp to 4, but rather to the current value of sp. fp serves as a reference to local information on the stack that remains constant during the execution of F. The old frame pointer, parameters and local variables are then stored at negative offsets from fp. 3.The parameters are passed in Registers r0 (a) and r1 (b); this is a convention defined in the Procedure Call Standard for the ARM Architecture. 3.Here, 8 Bytes of space are reserved on the stack, so that subsequent stack operations do not modify the local stack frame. 4.This copies r0 (Parameter a) into the local stack frame at address fp-8. 5.Loads r0 with .L3 contents 6.print string and pass parameters into r0, r1, and r2 7. Moves the constant value 0 in r0. 8.moves the value from r3 to r0. 9.pop the value out of pc