In computer programming, assembly language, often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported.
In computing, the Executable and Linkable Format is a common standard file format for executable files, object code, shared libraries, and core dumps. First published in the specification for the application binary interface (ABI) of the Unix operating system version named System V Release 4 (SVR4), and later in the Tool Interface Standard, it was quickly accepted among different vendors of Unix systems. In 1999, it was chosen as the standard binary file format for Unix and Unix-like systems on x86 processors by the 86open project.
The GNU Compiler Collection (GCC) is a collection of compilers from the GNU Project that support various programming languages, hardware architectures and operating systems. The Free Software Foundation (FSF) distributes GCC as free software under the GNU General Public License. GCC is a key component of the GNU toolchain which is used for most projects related to GNU and the Linux kernel. With roughly 15 million lines of code in 2019, GCC is one of the largest free programs in existence. It has played an important role in the growth of free software, as both a tool and an example.
MINIX is a Unix-like operating system based on a microkernel architecture. Since version 2.0, it has been POSIX compliant.
In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binary representation of a computer program which is actually read and interpreted by the computer. A program in machine code consists of a sequence of machine instructions.
In computing, cross-platform software is computer software that is designed to work in several computing platforms. Some cross-platform software requires a separate build for each platform, but some can be directly run on any platform without special preparation, being written in an interpreted language or compiled to portable bytecode for which the interpreters or run-time packages are common or standard components of all supported platforms.
Bytecode is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references that encode the result of compiler parsing and performing semantic analysis of things like type, scope, and nesting depths of program objects.
In software engineering, porting is the process of adapting software for the purpose of achieving some form of execution in a computing environment that is different from the one that a given program was originally designed for. The term is also used when software/hardware is changed to make them usable in different environments.
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 PC but generates code that runs on Android devices is a cross compiler.
A programming tool or software development tool is a computer program that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs, that can be combined to accomplish a task, much as one might use multiple hands to fix a physical object. The most basic tools are a source code editor and a compiler or interpreter, which are used ubiquitously and continuously. Other tools are used more or less depending on the language, development methodology, and individual engineer, often used for a discrete task, like a debugger or profiler. Tools may be discrete programs, executed separately – often from the command line – or may be parts of a single large program, called an integrated development environment (IDE). In many cases, particularly for simpler use, simple ad hoc techniques are used instead of a tool, such as print debugging instead of using a debugger, manual timing instead of a profiler, or tracking bugs in a text file or spreadsheet instead of a bug tracking system.
The GNU toolchain is a broad collection of programming tools produced by the GNU Project. These tools form a toolchain used for developing software applications and operating systems.
LLVM is a set of compiler and toolchain technologies that can be used to develop a frontend for any programming language and a backend for any instruction set architecture. LLVM is designed around a language-independent intermediate representation (IR) that serves as a portable, high-level assembly language that can be optimized with a variety of transformations over multiple passes. The name LLVM originally stood for Low Level Virtual Machine, though the project has expanded and the name is no longer officially an initialism.
In software engineering, retargeting is an attribute of software development tools that have been specifically designed to generate code for more than one computing platform.
a.out is a file format used in older versions of Unix-like computer operating systems for executables, object code, and, in later systems, shared libraries. This is an abbreviated form of "assembler output", the filename of the output of Ken Thompson's PDP-7 assembler. The term was subsequently applied to the format of the resulting file to contrast with other formats for object code.
This is an incomplete comparison of assemblers. Some assemblers are components of a compiler system for a high-level programming language and may have limited or no usable functionality outside of the compiler system. Some assemblers are hosted on the target processor and operating system, while other assemblers (cross-assemblers) may run under an unrelated operating system or processor. For example, assemblers for embedded systems are not usually hosted on the target system since it would not have the storage and terminal I/O to permit entry of a program from a keyboard. An assembler may have a single target processor or may have options to support multiple processor types.
The Tanenbaum–Torvalds debate was a written debate between Andrew S. Tanenbaum and Linus Torvalds, regarding the Linux kernel and kernel architecture in general. Tanenbaum, the creator of Minix, began the debate in 1992 on the Usenet discussion group comp.os.minix, arguing that microkernels are superior to monolithic kernels and therefore Linux was, even in 1992, obsolete. The debate has sometimes been considered a flame war.
The Portable C Compiler is an early compiler for the C programming language written by Stephen C. Johnson of Bell Labs in the mid-1970s, based in part on ideas proposed by Alan Snyder in 1973, and "distributed as the C compiler by Bell Labs... with the blessing of Dennis Ritchie."
Unix is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others.
NetBSD is a free and open-source Unix-like operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is available for many platforms, including servers, desktops, handheld devices, and embedded systems.
A code cave is a series of unused bytes in a process's memory. The code cave inside a process's memory is often a reference to a section that has capacity for injecting custom instructions.
