42 lines
2.0 KiB
Plaintext
42 lines
2.0 KiB
Plaintext
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Copyright Oliver Kowalke 2014.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt
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]
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[section:overview Overview]
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__boost_context__ is a foundational library that provides a sort of cooperative
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multitasking on a single thread. By providing an abstraction of the current
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execution state in the current thread, including the stack (with local
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variables) and stack pointer, all registers and CPU flags, and the instruction
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pointer, a execution context represents a specific point in the application's
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execution path. This is useful for building higher-level abstractions, like
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__coroutines__, __coop_threads__ or an equivalent to
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[@http://msdn.microsoft.com/en-us/library/9k7k7cf0%28v=vs.80%29.aspx C# keyword __yield__]
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in C++.
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__cc__/__con__ provides the means to suspend the current execution path and to
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transfer execution control, thereby permitting another context to run on the
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current thread. This state full transfer mechanism enables a context to suspend
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execution from within nested functions and, later, to resume from where it was
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suspended. While the execution path represented by a __con__ only runs on a
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single thread, it can be migrated to another thread at any given time.
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A [@http://en.wikipedia.org/wiki/Context_switch context switch] between threads
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requires system calls (involving the OS kernel), which can cost more than
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thousand CPU cycles on x86 CPUs. By contrast, transferring control vias
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__cc__/__con__ requires only few CPU cycles because it does not involve system
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calls as it is done within a single thread.
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All functions and classes are contained in the namespace __context_ns__.
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[note This library requires C++11!]
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[important Windows using fcontext_t: turn off global program optimization (/GL) and change /EHsc (compiler
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assumes that functions declared as extern "C" never throw a C++ exception) to /EHs (tells
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compiler assumes that functions declared as extern "C" may throw an exception).]
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[endsect]
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