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Global Constructor
(also known as ) 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. Form and usage Crt0 generally takes the form of an object file called , often written in assembly language, which is automatically included by the linker into every executable file it builds. contains the most basic parts of the runtime library. As such, the exact work it performs depends on the program's compiler, operating system and C standard library implementation. Beside the initialization work required by the environment and toolchain, can perform additional operations defined by the programmer, such as executing C++ global constructors and C functions carrying GCC's attribute. "crt" stands for "C runtime", and the zero stands for "the very beginning". However, when programs are compiled using GCC, it is also used for languages other than C. Alternative versions of are available for special ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linker (computing)
In computing, a linker or link editor is a computer system program that takes one or more object files (generated by a compiler or an assembler) and combines them into a single executable file, library file, or another "object" file. A simpler version that writes its output directly to memory is called the ''loader'', though loading is typically considered a separate process. Overview Computer programs typically are composed of several parts or modules; these parts/modules do not need to be contained within a single object file, and in such cases refer to each other by means of symbols as addresses into other modules, which are mapped into memory addresses when linked for execution. While the process of linking is meant to ultimately combine these independent parts, there are many good reasons to develop those separately at the source-level. Among these reasons are the ease of organizing several smaller pieces over a monolithic whole and the ability to better define the pur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GNU Compiler Collection
The GNU Compiler Collection (GCC) is an optimizing compiler produced by the GNU Project supporting various programming languages, hardware architectures and operating systems. The Free Software Foundation (FSF) distributes GCC as free software under the GNU General Public License (GNU GPL). GCC is a key component of the GNU toolchain and the standard compiler for most projects related to GNU and the Linux kernel. With roughly 15 million lines of code in 2019, GCC is one of the biggest free programs in existence. It has played an important role in the growth of free software, as both a tool and an example. When it was first released in 1987 by Richard Stallman, GCC 1.0 was named the GNU C Compiler since it only handled the C programming language. It was extended to compile C++ in December of that year. Front ends were later developed for Objective-C, Objective-C++, Fortran, Ada, D and Go, among others. The OpenMP and OpenACC specifications are also supported in the C and C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entry Point
In computer programming, an entry point is the place in a program where the execution of a program begins, and where the program has access to command line arguments. To start a program's execution, the loader or operating system passes control to its entry point. (During booting, the operating system itself is the program). This marks the transition from load time (and dynamic link time, if present) to run time. For some operating systems and programming languages, the entry point is in a runtime library, a set of support functions for the language. The library code initializes the program and then passes control to the program proper. In other cases, the program may initialize the runtime library itself. In simple systems, execution begins at the first statement, which is common in interpreted languages, simple executable formats, and boot loaders. In other cases, the entry point is at some other known memory address which can be an absolute address or relative address ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X86 Assembly Language
x86 assembly language is the name for the family of assembly languages which provide some level of backward compatibility with CPUs back to the Intel 8008 microprocessor, which was launched in April 1972. It is used to produce object code for the x86 class of processors. Regarded as a programming language, assembly is ''machine-specific'' and '' low-level''. Like all assembly languages, x86 assembly uses mnemonics to represent fundamental CPU instructions, or machine code. Assembly languages are most often used for detailed and time-critical applications such as small real-time embedded systems, operating-system kernels, and device drivers, but can also be used for other applications, such as the game '' Roller Coaster Tycoon'', 99% of which was written in x86 assembly. A compiler will sometimes produce assembly code as an intermediate step when translating a high-level program into machine code. Keywords Mnemonics and opcodes Each x86 assembly instruction is represented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X86-64
x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit version of the x86 instruction set, first released in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging mode. With 64-bit mode and the new paging mode, it supports vastly larger amounts of virtual memory and physical memory than was possible on its 32-bit predecessors, allowing programs to store larger amounts of data in memory. x86-64 also expands general-purpose registers to 64-bit, and expands the number of them from 8 (some of which had limited or fixed functionality, e.g. for stack management) to 16 (fully general), and provides numerous other enhancements. Floating-point arithmetic is supported via mandatory SSE2-like instructions, and x87/ MMX style registers are generally not used (but still available even in 64-bit mode); instead, a set of 16 vector registers, 128 bits each, is used. (Each register can store one or two double-preci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix. Linux is provided under the GNU General Public License version 2 only, but it contains files under other compatible licenses. Since the late 1990s, it has been included as part of a large number of operating system distributions, many of which are commonly also called Linux. Linux is deployed on a wide variety of computing systems, such as embedded devices, mobile devices (including its use in the Android operating system), personal computers, servers, mainframes, and supercomputers. It can be tailored for specific architectures and for several usage scenarios using a family of simple commands (that is, without the need of manually editing its source code ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gprof
Gprof is a performance analysis tool for Unix applications. It used a hybrid of instrumentation and samplingSusan L. Graham, Peter B. Kessler, and Marshall K. Mckusick''gprof: a Call Graph Execution Profiler''// Proceedings of the SIGPLAN '82 Symposium on Compiler Construction, SIGPLAN Notices, Vol. 17, No 6, pp. 120-126; doi: 10.1145/800230.806987 and was created as an extended version of the older "prof" tool. Unlike prof, gprof is capable of limited call graph collecting and printing. History GPROF was originally written by a group led by Susan L. Graham at the University of California, Berkeley for Berkeley Unix (4.2BSD). Another implementation was written as part of the GNU project for GNU Binutils in 1988 by Jay Fenlason. Implementation Instrumentation code is automatically inserted into the program code during compilation (for example, by using the '-pg' option of the gcc compiler), to gather caller-function data. A call to the monitor function 'mcount' is inserted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Profiling (computer Programming)
In software engineering, profiling ("program profiling", "software profiling") is a form of dynamic program analysis that measures, for example, the space (memory) or time complexity of a program, the usage of particular instructions, or the frequency and duration of function calls. Most commonly, profiling information serves to aid program optimization, and more specifically, performance engineering. Profiling is achieved by instrumenting either the program source code or its binary executable form using a tool called a ''profiler'' (or ''code profiler''). Profilers may use a number of different techniques, such as event-based, statistical, instrumented, and simulation methods. Gathering program events Profilers use a wide variety of techniques to collect data, including hardware interrupts, code instrumentation, instruction set simulation, operating system hooks, and performance counters. Use of profilers The output of a profiler may be: * A statistical ''sum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constructor (object-oriented Programming)
In class-based, object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. A constructor resembles an instance method, but it differs from a method in that it has no explicit return type, it is not implicitly inherited and it usually has different rules for scope modifiers. Constructors often have the same name as the declaring class. They have the task of initializing the object's data members and of establishing the invariant of the class, failing if the invariant is invalid. A properly written constructor leaves the resulting object in a ''valid'' state. Immutable objects must be initialized in a constructor. Most languages allow overloading the constructor in that there can be more than one constructor for a class, with differing parameters. Some languages take consideration of some sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C (programming Language)
C (''pronounced like the letter c'') is a General-purpose language, general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems, device drivers, protocol stacks, though decreasingly for application software. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the measuring programming language popularity, most widely used programming languages, with C compilers avail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toolchain
In software, a toolchain is a set of programming tools that is used to perform a complex software development task or to create a software product, which is typically another computer program or a set of related programs. In general, the tools forming a toolchain are executed consecutively so the output or resulting environment state of each tool becomes the input or starting environment for the next one, but the term is also used when referring to a set of related tools that are not necessarily executed consecutively. A simple software development toolchain may consist of a compiler and linker (which transform the source code into an executable program), libraries (which provide interfaces to the operating system), and a debugger (which is used to test and debug created programs). A complex software product such as a video game needs tools for preparing sound effects, music, textures, 3-dimensional models and animations, together with additional tools for combining these resourc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Standard Library
The C standard library or libc is the standard library for the C programming language, as specified in the ISO C standard.ISO/IEC (2018). '' ISO/IEC 9899:2018(E): Programming Languages - C ยง7'' Starting from the original ANSI C standard, it was developed at the same time as the C library POSIX specification, which is a superset of it. Since ANSI C was adopted by the International Organization for Standardization, the C standard library is also called the ISO C library. The C standard library provides macros, type definitions and functions for tasks such as string handling, mathematical computations, input/output processing, memory management, and several other operating system services. Application programming interface Header files The application programming interface (API) of the C standard library is declared in a number of header files. Each header file contains one or more function declarations, data type definitions, and macros. After a long period of stabi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
