In computing , source code , or simply code or source , is a plain text computer program written in a programming language . A programmer writes the human readable source code to control the behavior of a computer .
57-502: MoltenVK is a software library which allows Vulkan applications to run on top of Metal on Apple 's macOS , iOS , and tvOS operating systems . It is the first software component to be released for the Vulkan Portability Initiative, a project to have a subset of Vulkan run on platforms lacking native Vulkan drivers. There are some limitations compared with a native Vulkan implementation. MoltenVK
114-441: A compiler or an assembler . The resulting executable is machine code ready for the computer. Alternatively, source code can be executed without conversion via an interpreter . An interpreter loads the source code into memory. It simultaneously translates and executes each statement . A method that combines compilation and interpretation is to first produce bytecode . Bytecode is an intermediate representation of source code that
171-423: A computer program . Historically, a library consisted of subroutines (generally called functions today). The concept now includes other forms of executable code including classes and non-executable data including images and text . It can also refer to a collection of source code . For example, a program could use a library to indirectly make system calls instead of making those system calls directly in
228-462: A source-code editor that can alert the programmer to common errors. Modification often includes code refactoring (improving the structure without changing functionality) and restructuring (improving structure and functionality at the same time). Nearly every change to code will introduce new bugs or unexpected ripple effects , which require another round of fixes. Code reviews by other developers are often used to scrutinize new code added to
285-430: A trade secret . Proprietary, secret source code and algorithms are widely used for sensitive government applications such as criminal justice , which results in black box behavior with a lack of transparency into the algorithm's methodology. The result is avoidance of public scrutiny of issues such as bias. Access to the source code (not just the object code) is essential to modifying it. Understanding existing code
342-468: A Communication Pool (COMPOOL), roughly a library of header files. Another major contributor to the modern library concept came in the form of the subprogram innovation of FORTRAN . FORTRAN subprograms can be compiled independently of each other, but the compiler lacked a linker . So prior to the introduction of modules in Fortran-90, type checking between FORTRAN subprograms was impossible. By
399-529: A bottleneck. This led to the introduction of high-level programming languages such as Fortran in the mid-1950s. These languages abstracted away the details of the hardware, instead being designed to express algorithms that could be understood more easily by humans. As instructions distinct from the underlying computer hardware , software is therefore relatively recent, dating to these early high-level programming languages such as Fortran , Lisp , and Cobol . The invention of high-level programming languages
456-559: A feature called smart linking whereby the linker is aware of or integrated with the compiler, such that the linker knows how external references are used, and code in a library that is never actually used , even though internally referenced, can be discarded from the compiled application. For example, a program that only uses integers for arithmetic, or does no arithmetic operations at all, can exclude floating-point library routines. This smart-linking feature can lead to smaller application file sizes and reduced memory usage. Some references in
513-404: A library, a programmer only needs to know high-level information such as what items it contains at and how to use the items – not all of the internal details of the library. Libraries can use other libraries resulting in a hierarchy of libraries in a program. A library of executable code has a well-defined interface by which the functionality is invoked. For example, in C , a library function
570-436: A program are loaded from individual shared objects into memory at load time or runtime , rather than being copied by a linker when it creates a single monolithic executable file for the program. Shared libraries can be statically linked during compile-time, meaning that references to the library modules are resolved and the modules are allocated memory when the executable file is created. But often linking of shared libraries
627-589: A program or library module are stored in a relative or symbolic form which cannot be resolved until all code and libraries are assigned final static addresses. Relocation is the process of adjusting these references, and is done either by the linker or the loader . In general, relocation cannot be done to individual libraries themselves because the addresses in memory may vary depending on the program using them and other libraries they are combined with. Position-independent code avoids references to absolute addresses and therefore does not require relocation. When linking
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#1732787822400684-444: A project. The purpose of this phase is often to verify that the code meets style and maintainability standards and that it is a correct implementation of the software design . According to some estimates, code review dramatically reduce the number of bugs persisting after software testing is complete. Along with software testing that works by executing the code, static program analysis uses automated tools to detect problems with
741-406: A specific platform, source code can be ported to a different machine and recompiled there. For the same source code, object code can vary significantly—not only based on the machine for which it is compiled, but also based on performance optimization from the compiler. Most programs do not contain all the resources needed to run them and rely on external libraries . Part of the compiler's function
798-407: A suffix of .a ( archive , static library) or of .so (shared object, dynamically linked library). Some systems might have multiple names for a dynamically linked library. These names typically share the same prefix and have different suffixes indicating the version number. Most of the names are names for symbolic links to the latest version. For example, on some systems libfoo.so.2 would be
855-442: Is an overarching term that can refer to a code's correct and efficient behavior, its reusability and portability , or the ease of modification. It is usually more cost-effective to build quality into the product from the beginning rather than try to add it later in the development process. Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and easier to maintain . Maintainability
912-440: Is created (static linking), or whenever the program is used at runtime (dynamic linking). The references being resolved may be addresses for jumps and other routine calls. They may be in the main program, or in one module depending upon another. They are resolved into fixed or relocatable addresses (from a common base) by allocating runtime memory for the memory segments of each module referenced. Some programming languages use
969-452: Is frequently cited as a contributing factor to the maturation of their programming skills. Some people consider source code an expressive artistic medium . Source code often contains comments —blocks of text marked for the compiler to ignore. This content is not part of the program logic, but is instead intended to help readers understand the program. Companies often keep the source code confidential in order to hide algorithms considered
1026-400: Is invoked via C's normal function call capability. The linker generates code to call a function via the library mechanism if the function is available from a library instead of from the program itself. The functions of a library can be connected to the invoking program at different program lifecycle phases . If the code of the library is accessed during the build of the invoking program, then
1083-496: Is necessary to understand how it works and before modifying it. The rate of understanding depends both on the code base as well as the skill of the programmer. Experienced programmers have an easier time understanding what the code does at a high level. Software visualization is sometimes used to speed up this process. Many software programmers use an integrated development environment (IDE) to improve their productivity. IDEs typically have several features built in, including
1140-430: Is performed during the creation of an executable or another object file, it is known as static linking or early binding . In this case, the linking is usually done by a linker , but may also be done by the compiler . A static library , also known as an archive , is one intended to be statically linked. Originally, only static libraries existed. Static linking must be performed when any modules are recompiled. All of
1197-500: Is postponed until they are loaded. Although originally pioneered in the 1960s, dynamic linking did not reach the most commonly-used operating systems until the late 1980s. It was generally available in some form in most operating systems by the early 1990s. During this same period, object-oriented programming (OOP) was becoming a significant part of the programming landscape. OOP with runtime binding requires additional information that traditional libraries do not supply. In addition to
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#17327878224001254-470: Is quickly interpreted. The first programmable computers, which appeared at the end of the 1940s, were programmed in machine language (simple instructions that could be directly executed by the processor). Machine language was difficult to debug and was not portable between different computer systems. Initially, hardware resources were scarce and expensive, while human resources were cheaper. As programs grew more complex, programmer productivity became
1311-631: Is that many software engineering courses do not emphasize it. Development engineers who know that they will not be responsible for maintaining the software do not have an incentive to build in maintainability. The situation varies worldwide, but in the United States before 1974, software and its source code was not copyrightable and therefore always public domain software . In 1974, the US Commission on New Technological Uses of Copyrighted Works (CONTU) decided that "computer programs, to
1368-477: Is the quality of software enabling it to be easily modified without breaking existing functionality. Following coding conventions such as using clear function and variable names that correspond to their purpose makes maintenance easier. Use of conditional loop statements only if the code could execute more than once, and eliminating code that will never execute can also increase understandability. Many software development organizations neglect maintainability during
1425-418: Is to link these files in such a way that the program can be executed by the hardware. Software developers often use configuration management to track changes to source code files ( version control ). The configuration management system also keeps track of which object code file corresponds to which version of the source code file. The number of lines of source code is often used as a metric when evaluating
1482-604: The UNIX world, which uses different file extensions, when linking against .LIB file in Windows one must first know if it is a regular static library or an import library. In the latter case, a .DLL file must be present at runtime. Source code Since a computer, at base, only understands machine code , source code must be translated before a computer can execute it. The translation process can be implemented three ways. Source code can be converted into machine code by
1539-523: The Vulkan API with the aid of MoltenVK, and that they had made an arrangement with developer The Brenwill Workshop Ltd to release MoltenVK as open-source software under the Apache License version 2.0. On May 30, 2018, Qt was updated with Vulkan for Qt on macOS using MoltenVK. On May 31, 2018, optional Vulkan support for Dota 2 on macOS was released. Benchmarks for the game were available
1596-556: The dependencies to external libraries in build configuration files (such as a Maven Pom in Java). Another library technique uses completely separate executables (often in some lightweight form) and calls them using a remote procedure call (RPC) over a network to another computer. This maximizes operating system re-use: the code needed to support the library is the same code being used to provide application support and security for every other program. Additionally, such systems do not require
1653-426: The development phase, even though it will increase long-term costs. Technical debt is incurred when programmers, often out of laziness or urgency to meet a deadline, choose quick and dirty solutions rather than build maintainability into their code. A common cause is underestimates in software development effort estimation , leading to insufficient resources allocated to development. A challenge with maintainability
1710-532: The engine would have a library of its own." In 1947 Goldstine and von Neumann speculated that it would be useful to create a "library" of subroutines for their work on the IAS machine , an early computer that was not yet operational at that time. They envisioned a physical library of magnetic wire recordings , with each wire storing reusable computer code. Inspired by von Neumann, Wilkes and his team constructed EDSAC . A filing cabinet of punched tape held
1767-406: The extent that they embody an author's original creation, are proper subject matter of copyright". Proprietary software is rarely distributed as source code. Although the term open-source software literally refers to public access to the source code , open-source software has additional requirements: free redistribution, permission to modify the source code and release derivative works under
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1824-536: The filename for the second major interface revision of the dynamically linked library libfoo . The .la files sometimes found in the library directories are libtool archives, not usable by the system as such. The system inherits static library conventions from BSD , with the library stored in a .a file, and can use .so -style dynamically linked libraries (with the .dylib suffix instead). Most libraries in macOS, however, consist of "frameworks", placed inside special directories called " bundles " which wrap
1881-628: The following day, showing better performance using Vulkan and MoltenVK compared to OpenGL. On July 20, 2018, Wine was updated with Vulkan support on macOS using MoltenVK. On 29 July 2018, the first app using MoltenVK was accepted onto the App Store , after initially being rejected. On 6 August 2018, Google open-sourced Filament, a crossplatform real-time physically based rendering engine with MoltenVK for macOS/iOS. On November 28, 2018, Valve released Artifact , their first Vulkan-only game on macOS using MoltenVK. On 29 January 2019, MoltenVK 1.0.32
1938-439: The instantiated objects residing only in memory (although potentially able to be made persistent in separate files). In others, like Smalltalk , the class libraries are merely the starting point for a system image that includes the entire state of the environment, classes and all instantiated objects. Today most class libraries are stored in a package repository (such as Maven Central for Java). Client code explicitly declare
1995-475: The instructions can be carried out. After being compiled, the program can be saved as an object file and the loader (part of the operating system) can take this saved file and execute it as a process on the computer hardware. Some programming languages use an interpreter instead of a compiler. An interpreter converts the program into machine code at run time , which makes them 10 to 100 times slower than compiled programming languages. Software quality
2052-474: The library is called a static library . An alternative is to build the program executable to be separate from the library file. The library functions are connected after the executable is started, either at load-time or runtime . In this case, the library is called a dynamic library . Most compiled languages have a standard library , although programmers can also create their own custom libraries. Most modern software systems provide libraries that implement
2109-958: The library to exist on the same machine, but can forward the requests over the network. However, such an approach means that every library call requires a considerable amount of overhead. RPC calls are much more expensive than calling a shared library that has already been loaded on the same machine. This approach is commonly used in a distributed architecture that makes heavy use of such remote calls, notably client-server systems and application servers such as Enterprise JavaBeans . Code generation libraries are high-level APIs that can generate or transform byte code for Java . They are used by aspect-oriented programming , some data access frameworks, and for testing to generate dynamic proxy objects. They also are used to intercept field access. The system stores libfoo.a and libfoo.so files in directories such as /lib , /usr/lib or /usr/local/lib . The filenames always start with lib , and end with
2166-463: The library's required files and metadata. For example, a framework called MyFramework would be implemented in a bundle called MyFramework.framework , with MyFramework.framework/MyFramework being either the dynamically linked library file or being a symlink to the dynamically linked library file in MyFramework.framework/Versions/Current/MyFramework . Dynamic-link libraries usually have
2223-501: The majority of the system services. Such libraries have organized the services which a modern application requires. As such, most code used by modern applications is provided in these system libraries. The idea of a computer library dates back to the first computers created by Charles Babbage . An 1888 paper on his Analytical Engine suggested that computer operations could be punched on separate cards from numerical input. If these operation punch cards were saved for reuse then "by degrees
2280-528: The mid 1960s, copy and macro libraries for assemblers were common. Starting with the popularity of the IBM System/360 , libraries containing other types of text elements, e.g., system parameters, also became common. In IBM's OS/360 and its successors this is called a partitioned data set . The first object-oriented programming language, Simula , developed in 1965, supported adding classes to libraries via its compiler. Libraries are important in
2337-488: The modules required by a program are sometimes statically linked and copied into the executable file. This process, and the resulting stand-alone file, is known as a static build of the program. A static build may not need any further relocation if virtual memory is used and no address space layout randomization is desired. A shared library or shared object is a file that is intended to be shared by executable files and further shared object files . Modules used by
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2394-472: The names and entry points of the code located within, they also require a list of the objects they depend on. This is a side-effect of one of OOP's core concepts, inheritance, which means that parts of the complete definition of any method may be in different places. This is more than simply listing that one library requires the services of another: in a true OOP system, the libraries themselves may not be known at compile time , and vary from system to system. At
2451-465: The productivity of computer programmers, the economic value of a code base, effort estimation for projects in development, and the ongoing cost of software maintenance after release. Source code is also used to communicate algorithms between people – e.g., code snippets online or in books. Computer programmers may find it helpful to review existing source code to learn about programming techniques. The sharing of source code between developers
2508-430: The program linking or binding process, which resolves references known as links or symbols to library modules. The linking process is usually automatically done by a linker or binder program that searches a set of libraries and other modules in a given order. Usually it is not considered an error if a link target can be found multiple times in a given set of libraries. Linking may be done when an executable file
2565-404: The program. A library can be used by multiple, independent consumers (programs and other libraries). This differs from resources defined in a program which can usually only be used by that program. When a consumer uses a library resource, it gains the value of the library without having to implement it itself. Libraries encourage code reuse in a modular fashion. When writing code that uses
2622-424: The rough OOP equivalent of older types of code libraries. They contain classes , which describe characteristics and define actions ( methods ) that involve objects. Class libraries are used to create instances , or objects with their characteristics set to specific values. In some OOP languages, like Java , the distinction is clear, with the classes often contained in library files (like Java's JAR file format ) and
2679-424: The same time many developers worked on the idea of multi-tier programs, in which a "display" running on a desktop computer would use the services of a mainframe or minicomputer for data storage or processing. For instance, a program on a GUI-based computer would send messages to a minicomputer to return small samples of a huge dataset for display. Remote procedure calls (RPC) already handled these tasks, but there
2736-414: The source code. Many IDEs support code analysis tools, which might provide metrics on the clarity and maintainability of the code. Debuggers are tools that often enable programmers to step through execution while keeping track of which source code corresponds to each change of state. Source code files in a high-level programming language must go through a stage of preprocessing into machine code before
2793-528: The status of the "next big thing" in the programming world. There were a number of efforts to create systems that would run across platforms, and companies competed to try to get developers locked into their own system. Examples include IBM 's System Object Model (SOM/DSOM), Sun Microsystems ' Distributed Objects Everywhere (DOE), NeXT 's Portable Distributed Objects (PDO), Digital 's ObjectBroker , Microsoft's Component Object Model (COM/DCOM), and any number of CORBA -based systems. Class libraries are
2850-521: The subroutine library for this computer. Programs for EDSAC consisted of a main program and a sequence of subroutines copied from the subroutine library. In 1951 the team published the first textbook on programming, The Preparation of Programs for an Electronic Digital Computer , which detailed the creation and the purpose of the library. COBOL included "primitive capabilities for a library system" in 1959, but Jean Sammet described them as "inadequate library facilities" in retrospect. JOVIAL has
2907-475: The suffix *.DLL , although other file name extensions may identify specific-purpose dynamically linked libraries, e.g. *.OCX for OLE libraries. The interface revisions are either encoded in the file names, or abstracted away using COM-object interfaces. Depending on how they are compiled, *.LIB files can be either static libraries or representations of dynamically linkable libraries needed only during compilation, known as " import libraries ". Unlike in
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#17327878224002964-550: Was first released as a proprietary and commercially licensed product by The Brenwill Workshop on July 27, 2016. On July 31, 2017, Khronos announced the formation of the Vulkan Portability Technical Subgroup. On February 26, 2018, Khronos announced that Vulkan became available on macOS and iOS products through the MoltenVK library. Valve announced that Dota 2 will run on macOS using
3021-467: Was no standard RPC system. Soon the majority of the minicomputer and mainframe vendors instigated projects to combine the two, producing an OOP library format that could be used anywhere. Such systems were known as object libraries , or distributed objects , if they supported remote access (not all did). Microsoft's COM is an example of such a system for local use. DCOM, a modified version of COM, supports remote access. For some time object libraries held
3078-423: Was released with early prototype of Vulkan Portability Extensions. RPCS3 and Dolphin emulators were updated with Vulkan support on macOS using MoltenVK. On 13 April 2019, MoltenVK 1.0.34 was released with support for tessellation . On July 30, 2019, MoltenVK 1.0.36 was released targeting Metal 3.0. On July 31, 2020, MoltenVK 1.0.44 was released, adding support for the tvOS platform. On January 23, 2020, MoltenVK
3135-407: Was released, adding full support for Vulkan 1.2 as of Vulkan SDK 1.3.231. In January 2023, MoltenVK 1.2.2 added support for Vulkan as of SDK 1.3.239, while this version of Vulkan SDK fixed some issues with the interconnectivity with Metal API. Library (computing) In computer science , a library is a collection of resources that is leveraged during software development to implement
3192-480: Was simultaneous with the compilers needed to translate the source code automatically into machine code that can be directly executed on the computer hardware . Source code is the form of code that is modified directly by humans, typically in a high-level programming language. Object code can be directly executed by the machine and is generated automatically from the source code, often via an intermediate step, assembly language . While object code will only work on
3249-494: Was updated to support for some of the new features of Vulkan 1.2 , as of Vulkan SDK 1.2.121. On October 1, 2020, MoltenVK 1.1.0 was released, adding full support for Vulkan 1.1 , as of Vulkan SDK 1.2.154. On 9 December 2020, MoltenVK 1.1.1 was released, providing support for Vulkan on Apple silicon GPUs and support for the Mac Catalyst platform for porting iOS/iPadOS apps to macOS. On October 18, 2022, MoltenVK 1.2.0
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