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Operating System Engineering, Lecture 3
6.828 2012 Lecture 3: O/S Organization plan: O/S organization processes isolation topic: overall o/s design what should the main components be? what should the interfaces look like? why have an o/s at all? why not just a library? then apps are free to use it, or not -- flexible some tiny O/Ss for embedded processors work this way key requirement: support multiple activities multiplexing isolation interaction helpful approach: abstract services rather than raw hardware file system, not raw disk TCP, not raw ethernet processes, not raw CPU/memory abstractions often ease multiplexing and interaction and more convenient and portable note: i'm going to focus on mainstream designs (xv6, Linux, &c) for *every* aspect, someone has done it a different way! example: exokernel and VMM does *not* abstract anything! xv6 has only a few abstractions / services processes (cpu, mem) I/O (file descriptors) file system i'm going to focus on xv6 processes today a process is a running program it has its own memory, share of CPU, FDs, parent, children, &c it uses system calls to interact outside itself to get at kernel services xv6 basic design here very traditional (UNIX/Linux/&c) xv6 user/kernel organization h/w, kernel, user kernel is a big program services: process, FS, net low-level: devices, VM all of kernel runs w/ full hardware privilege (very convenient) system calls switch between user and kernel 1 good: easy for sub-systems to cooperate (e.g. paging and file system) bad: interactions => complex, bugs are easy, no isolation within o/s called "monolithic"; -
Higher-Order Functions 15-150: Principles of Functional Programming – Lecture 13
Higher-order Functions 15-150: Principles of Functional Programming { Lecture 13 Giselle Reis By now you might feel like you have a pretty good idea of what is going on in functional program- ming, but in reality we have used only a fragment of the language. In this lecture we see what more we can do and what gives the name functional to this paradigm. Let's take a step back and look at ML's typing system: we have basic types (such as int, string, etc.), tuples of types (t*t' ) and functions of a type to a type (t ->t' ). In a grammar style (where α is a basic type): τ ::= α j τ ∗ τ j τ ! τ What types allowed by this grammar have we not used so far? Well, we could, for instance, have a function below a tuple. Or even a function within a function, couldn't we? The following are completely valid types: int*(int -> int) int ->(int -> int) (int -> int) -> int The first one is a pair in which the first element is an integer and the second one is a function from integers to integers. The second one is a function from integers to functions (which have type int -> int). The third type is a function from functions to integers. The two last types are examples of higher-order functions1, i.e., a function which: • receives a function as a parameter; or • returns a function. Functions can be used like any other value. They are first-class citizens. Maybe this seems strange at first, but I am sure you have used higher-order functions before without noticing it. -
The Design of a Pascal Compiler Mohamed Sharaf, Devaun Mcfarland, Aspen Olmsted Part I
The Design of A Pascal Compiler Mohamed Sharaf, Devaun McFarland, Aspen Olmsted Part I Mohamed Sharaf Introduction The Compiler is for the programming language PASCAL. The design decisions Concern the layout of program and data, syntax analyzer. The compiler is written in its own language. The compiler is intended for the CDC 6000 computer family. CDC 6000 is a family of mainframe computer manufactured by Control Data Corporation in the 1960s. It consisted of CDC 6400, CDC 6500, CDC 6600 and CDC 6700 computers, which all were extremely rapid and efficient for their time. It had a distributed architecture and was a reduced instruction set (RISC) machine many years before such a term was invented. Pascal Language Imperative Computer Programming Language, developed in 1971 by Niklaus Wirth. The primary unit in Pascal is the procedure. Each procedure is represented by a data segment and the program/code segment. The two segments are disjoint. Compiling Programs: Basic View Machine Pascal languag program Pascal e compile program filename . inpu r gp output a.out p t c Representation of Data Compute all the addresses at compile time to optimize certain index calculation. Entire variables always are assigned at least one full PSU “Physical Storage Unit” i.e CDC6000 has ‘wordlength’ of 60 bits. Scalar types Array types the first term is computed by the compiler w=a+(i-l)*s Record types: reside only within one PSU if it is represented as packed. If it is not packed its size will be the size of the largest possible variant. Data types … Powerset types The set operations of PASCAL are realized by the conventional bit-parallel logical instructions ‘and ‘ for intersection, ‘or’ for union File types The data transfer between the main store buffer and the secondary store is performed by a Peripheral Processor (PP). -
Typescript Language Specification
TypeScript Language Specification Version 1.8 January, 2016 Microsoft is making this Specification available under the Open Web Foundation Final Specification Agreement Version 1.0 ("OWF 1.0") as of October 1, 2012. The OWF 1.0 is available at http://www.openwebfoundation.org/legal/the-owf-1-0-agreements/owfa-1-0. TypeScript is a trademark of Microsoft Corporation. Table of Contents 1 Introduction ................................................................................................................................................................................... 1 1.1 Ambient Declarations ..................................................................................................................................................... 3 1.2 Function Types .................................................................................................................................................................. 3 1.3 Object Types ...................................................................................................................................................................... 4 1.4 Structural Subtyping ....................................................................................................................................................... 6 1.5 Contextual Typing ............................................................................................................................................................ 7 1.6 Classes ................................................................................................................................................................................. -
Scala Tutorial
Scala Tutorial SCALA TUTORIAL Simply Easy Learning by tutorialspoint.com tutorialspoint.com i ABOUT THE TUTORIAL Scala Tutorial Scala is a modern multi-paradigm programming language designed to express common programming patterns in a concise, elegant, and type-safe way. Scala has been created by Martin Odersky and he released the first version in 2003. Scala smoothly integrates features of object-oriented and functional languages. This tutorial gives a great understanding on Scala. Audience This tutorial has been prepared for the beginners to help them understand programming Language Scala in simple and easy steps. After completing this tutorial, you will find yourself at a moderate level of expertise in using Scala from where you can take yourself to next levels. Prerequisites Scala Programming is based on Java, so if you are aware of Java syntax, then it's pretty easy to learn Scala. Further if you do not have expertise in Java but you know any other programming language like C, C++ or Python, then it will also help in grasping Scala concepts very quickly. Copyright & Disclaimer Notice All the content and graphics on this tutorial are the property of tutorialspoint.com. Any content from tutorialspoint.com or this tutorial may not be redistributed or reproduced in any way, shape, or form without the written permission of tutorialspoint.com. Failure to do so is a violation of copyright laws. This tutorial may contain inaccuracies or errors and tutorialspoint provides no guarantee regarding the accuracy of the site or its contents including this tutorial. If you discover that the tutorialspoint.com site or this tutorial content contains some errors, please contact us at [email protected] TUTORIALS POINT Simply Easy Learning Table of Content Scala Tutorial .......................................................................... -
Entry Point Specification
EMV® Contactless Specifications for Payment Systems Book B Entry Point Specification Version 2.6 July 2016 © 2016 EMVCo, LLC. All rights reserved. Reproduction, distribution and other use of this document is permitted only pursuant to the applicable agreement between the user and EMVCo found at www.emvco.com. EMV® is a registered trademark or trademark of EMVCo, LLC in the United States and other countries. EMV Contactless Book B Entry Point Specification version 2.6 Legal Notice The EMV® Specifications are provided “AS IS” without warranties of any kind, and EMVCo neither assumes nor accepts any liability for any errors or omissions contained in these Specifications. EMVCO DISCLAIMS ALL REPRESENTATIONS AND WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT, AS TO THESE SPECIFICATIONS. EMVCo makes no representations or warranties with respect to intellectual property rights of any third parties in or in relation to the Specifications. EMVCo undertakes no responsibility to determine whether any implementation of the EMV® Specifications may violate, infringe, or otherwise exercise the patent, copyright, trademark, trade secret, know-how, or other intellectual property rights of third parties, and thus any person who implements any part of the EMV® Specifications should consult an intellectual property attorney before any such implementation. Without limiting the foregoing, the Specifications may provide for the use of public key encryption and other technology, which may be the subject matter of patents in several countries. Any party seeking to implement these Specifications is solely responsible for determining whether its activities require a license to any such technology, including for patents on public key encryption technology. -
Smalltalk Smalltalk
3/8/2008 CSE 3302 Programming Languages Smalltalk Everyygthing is obj ect. Obj ects communicate by messages. Chengkai Li Spring 2008 Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 1 CSE3302 Programming Languages, UT-Arlington 2 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 Object Hierarchy Object UndefinedObject Boolean Magnitude Collection No Data Type. True False Set … There is only Class. Char Number … Fraction Integer Float Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 3 CSE3302 Programming Languages, UT-Arlington 4 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 Syntax • Smalltalk is really “small” – Only 6 keywords (pseudo variables) – Class, object, variable, method names are self explanatory Sma llta lk Syn tax is Simp le. – Only syntax for calling method (messages) and defining method. • No syntax for control structure • No syntax for creating class Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 5 CSE3302 Programming Languages, UT-Arlington 6 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 1 3/8/2008 Expressions Literals • Literals • Number: 3 3.5 • Character: $a • Pseudo Variables • String: ‘ ’ (‘Hel’,’lo!’ and ‘Hello!’ are two objects) • Symbol: # (#foo and #foo are the same object) • Variables • Compile-time (literal) array: #(1 $a 1+2) • Assignments • Run-time (dynamic) array: {1. $a. 1+2} • Comment: “This is a comment.” • Blocks • Messages Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 7 CSE3302 Programming Languages, UT-Arlington 8 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 Pseudo Variables Variables • Instance variables. -
Python Functions
PPYYTTHHOONN FFUUNNCCTTIIOONNSS http://www.tutorialspoint.com/python/python_functions.htm Copyright © tutorialspoint.com A function is a block of organized, reusable code that is used to perform a single, related action. Functions provide better modularity for your application and a high degree of code reusing. As you already know, Python gives you many built-in functions like print, etc. but you can also create your own functions. These functions are called user-defined functions. Defining a Function You can define functions to provide the required functionality. Here are simple rules to define a function in Python. Function blocks begin with the keyword def followed by the function name and parentheses ( ). Any input parameters or arguments should be placed within these parentheses. You can also define parameters inside these parentheses. The first statement of a function can be an optional statement - the documentation string of the function or docstring. The code block within every function starts with a colon : and is indented. The statement return [expression] exits a function, optionally passing back an expression to the caller. A return statement with no arguments is the same as return None. Syntax def functionname( parameters ): "function_docstring" function_suite return [expression] By default, parameters have a positional behavior and you need to inform them in the same order that they were defined. Example The following function takes a string as input parameter and prints it on standard screen. def printme( str ): "This prints a passed string into this function" print str return Calling a Function Defining a function only gives it a name, specifies the parameters that are to be included in the function and structures the blocks of code. -
Challenges in Debugging Dynamically Compiled Languages As Exemplified by C# Debugger for Tizen
Samsung R&D Institute Russia Center of System Software Challenges in debugging dynamically compiled languages as exemplified by C# debugger for Tizen Dmitri Botcharnikov 1 Agenda Dynamically compiled languages Tizen .NET Debugging Challenges Tizen .NET Debugger internals Future plans 2 Dynamically compiled languages Dynamically (Just-In-Time) compiled languages VM manages low-level details: memory allocation, exception handling But for debuggers… 3 Tizen .NET Visual Studio Tools for Tizen preview were released C# was added to Tizen Over 1,400,000 C# developers worldwide Tizen running on 50 millions Samsung devices (TV, wearables, mobile, IoT) http://developer.tizen.org 4 Technologies Tizen OS (emulator, platform-specific APIs) Xamarin.Forms .NET Core (CoreCLR, CoreFX, Roslyn) Visual Studio 2015 (Windows) 5 C# Compilation & Execution C# source MSIL Output CLR Roslyn JIT Language-specific compiler: C# => MSIL CLR JIT compiler: MSIL => native code 6 Debugging Challenges Source code to native code mapping ◦ C# compiler generates debugging information for source code to MSIL mapping Stepping in and over ◦ Stepping into not yet compiled code ◦ Managed exception handlers ◦ Lambdas, closures & iterators Local variables & arguments inspection ◦ C# compiler generates debugging information for MSIL variables 7 LLDB Subproject of LLVM (http://lldb.llvm.org) Native debugger builds on LLVM and Clang libraries Supports X86 and ARM architectures 8 SOS debugger plug-in Plug-in for LLDB (libsosplugin.so, libsos.so) Port of SOS.dll -
LLDB Tutorial: Adding Debugger Support for Your Target LLVM 2016 Tutorial
LLDB Tutorial: Adding debugger support for your target LLVM 2016 tutorial Deepak Panickal Andrzej Warzyński Codeplay Soware @codeplayso March 18, 2016 Outline • LLDB architecture crash course I Overview of LLDB I User scenarios such as breakpoints, stack-walking etc. I Debugging ps • Both generic and specialized architectures are covered I MSP430 lldb debugging, which we have implemented for this tutorial I github.com/codeplaysoftware/lldb-msp430 I ARM architecture is also referred to for the generic cases • Focusing on debugging ELF executables on Linux EuroLLVM 2016 Outline 2 / 54 Overview Part 1: The Basics Part 2: ELF And Architecture Support Part 3: Registers Part 4: Memory and Breakpoints Part 5: Other Key Features Part 6: Debugging Tips Part 7: MSP430 Quick Recap EuroLLVM 2016 Outline 3 / 54 Part 1 The Basics EuroLLVM 2016 Part 1: The Basics 4 / 54 LLDB - Architecture lldb user driver TCP Socket GDB RSP . lldb-server debug API Architecture of LLDB LLDB offers mulple opons: I user drivers: command line, lldb-mi, Python I debug API: ptrace/simulator/runme/actual drivers EuroLLVM 2016 Part 1: The Basics 5 / 54 lldb/lldb-server lldb • Runs on host • Interacts with the user • Understands symbols, DWARF informaon, data formats, etc. • Plugin architecture I ProcessGDBRemote, DynamicLoaderPOSIXDYLD, ABISysV_msp430 are some... lldb-server • Runs on both remote and host, communicates to lldb via RSP over whichever medium is available • Interacts with the hardware/simulator • Deals with binary data and memory addresses • Plugin architecture I ObjectFileELF, ProcessLinux, are some... EuroLLVM 2016 Part 1: The Basics 6 / 54 GDB Remote Serial Protocol • Simple, ASCII message based protocol • Designed for debugging remote targets • Originally developed for gdb<->gdbserver communicaon • Extended for LLDB, see lldb-gdb-remote.txt Packet structure: checksum $. -
Eff Directly in Ocaml
Eff Directly in OCaml Oleg Kiselyov KC Sivaramakrishnan Tohoku University, Japan University of Cambridge, UK [email protected] [email protected] The language Eff is an OCaml-like language serving as a prototype implementation of the theory of algebraic effects, intended for experimentation with algebraic effects on a large scale. We present the embedding of Eff into OCaml, using the library of delimited continuations or the multicore OCaml branch. We demonstrate the correctness of the embedding denotationally, re- lying on the tagless-final–style interpreter-based denotational semantics, including the novel, direct denotational semantics of multi-prompt delimited control. The embedding is systematic, lightweight, performant and supports even higher-order, ‘dynamic’ effects with their polymorphism. OCaml thus may be regarded as another implementation of Eff, broadening the scope and appeal of that language. 1 Introduction Algebraic effects [33, 32] are becoming a more and more popular approach for expressing and com- posing computational effects. There are implementations of algebraic effects in Haskell [18, 22], Idris [4], OCaml [10, 18], Koka [27], Scala1, Javascript2, PureScript3, and other languages. The most direct embodiment of algebraic effect theory is the language Eff4 “built to test the mathematical ideas of alge- braic effects in practice”. It is an OCaml-like language with the native facilities (syntax, type system) to declare effects and their handlers [2]. It is currently implemented as an interpreter, with an optimizing compiler to OCaml in the works. Rather than compile Eff to OCaml, we embed it. After all, save for algebraic effects, Eff truly is a subset of OCaml and can be interpreted or compiled as a regular OCaml code. -
An Overview of the Scala Programming Language
An Overview of the Scala Programming Language Second Edition Martin Odersky, Philippe Altherr, Vincent Cremet, Iulian Dragos Gilles Dubochet, Burak Emir, Sean McDirmid, Stéphane Micheloud, Nikolay Mihaylov, Michel Schinz, Erik Stenman, Lex Spoon, Matthias Zenger École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne, Switzerland Technical Report LAMP-REPORT-2006-001 Abstract guage for component software needs to be scalable in the sense that the same concepts can describe small as well as Scala fuses object-oriented and functional programming in large parts. Therefore, we concentrate on mechanisms for a statically typed programming language. It is aimed at the abstraction, composition, and decomposition rather than construction of components and component systems. This adding a large set of primitives which might be useful for paper gives an overview of the Scala language for readers components at some level of scale, but not at other lev- who are familar with programming methods and program- els. Second, we postulate that scalable support for compo- ming language design. nents can be provided by a programming language which unies and generalizes object-oriented and functional pro- gramming. For statically typed languages, of which Scala 1 Introduction is an instance, these two paradigms were up to now largely separate. True component systems have been an elusive goal of the To validate our hypotheses, Scala needs to be applied software industry. Ideally, software should be assembled in the design of components and component systems. Only from libraries of pre-written components, just as hardware is serious application by a user community can tell whether the assembled from pre-fabricated chips.