crt0 (also known as c0) is a set of execution startup routines linked into a C program that performs any initialization work required before calling the program’s main function. crt stands for C runtime. crt is a set of execution startup routines compiled into a program which performs any initialization work required before calling the program’s main function. It is a basic runtime library/system. The work performed by crt depends on the ABI, machine, compiler, operating system and C standard library implementation. The C Runtime system must carry out the following tasks. Set up the target platform in a consistent state. For example setting up appropriate exception … Continue reading The C Runtime Initialization

* Introduction Building a program from source code typically involves a few common steps: – Writing the source code – Process the code to expand all *#include* files, macros, etc. – Compiling the expanded source code to machine assembly language – Compiling assembly language to machine  binary code – Linking binary code in multiple files or libraries into   an executable binary program Executing these steps on a small set of source code may be manageable, but as the source code gets larger, the  process becomes more complex. * The Make System The *make* command looks for a file called … Continue reading Introduction of Make

8085 Microprocessor: The salient features of 8085 μp are : It is a 8 bit microprocessor. It is manufactured with N-MOS technology. It has 16 bit address bus and hence can address up-to 216 = 65536 bytes (64KB) memory locations through A0-A15. The first 8 lines of address bus and 8 lines of data-bus are multiplexed AD0 – AD7. Data bus is a group of 8 lines D0 – D7. It supports external interrupt request. A 16 bit program counter (PC). A 16 bit stack pointer (SP). Six 8-bit general purpose register arranged in pairs: BC,DE, HL. It requires a … Continue reading Micro Processor(x86 Basic)

Write a sample C program with errors for debugging purpose To learn C program debugging, let us create the following C program that calculates and prints the factorial of a number. However, this C program contains some errors in it for our debugging purpose. $ vim factorial.c # include <stdio.h> int main() { int i, num, j; printf (“Enter the number: “); scanf (“%d”, &num ); for (i=1; i<num; i++) j=j*i; printf(“The factorial of %d is %d\n”,num,j); } $ cc factorial.c $ ./a.out Enter the number: 3 The factorial of 3 is 12548672 Continue reading Introduction to gdb (Gnu Debugger)

=====> COMPILATION PROCESS <====== | |—-> Input is Source file(.c) | V +=================+ | | | C Preprocessor | | | +=================+ | | —> Pure C file ( comd:cc -E <file.name> ) | V +=================+ | | | Lexical Analyzer| | | +—————–+ | | | Syntax Analyzer | | | +—————–+ | | | Semantic Analyze| | | +—————–+ | | | Pre Optimization| | | +—————–+ | | | Code generation | | | +—————–+ | | | Post Optimize | | | +=================+ | |—> Assembly code (comd: cc -S <file.name> ) | V +=================+ | … Continue reading Compilation Process

C and Assembly: Many of us ( system/Embedded programmers) Who use C/Cpp for Firmware/Software Development is more comfortable writing in C/Cpp, and C is a mid-level language and Cpp being High-Level Language (in comparison to Assembly, which is a low-level language), and spares the programmers some of the details of the actual implementation. However, some of the low-level tasks can only be implemented in assembly (e.g. StartUp Code).Also, it is frequently useful for the programmer to look at the assembly output of the C compiler, and hand-edit or hand optimize the assembly code in ways that the compiler cannot. Assembly is also … Continue reading Mixed C and Assembly Programming (Embedded Systems)