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f4f4caab0e
I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
50 lines
2.4 KiB
Markdown
50 lines
2.4 KiB
Markdown
SYNOPSIS
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Cosmopolitan Standard Library.
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OVERVIEW
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This directory defines static archives defining functions, like
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printf(), mmap(), win32, etc. Please note that the Cosmopolitan
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build configuration doesn't link any C/C++ library dependencies
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by default, so you still have the flexibility to choose the one
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provided by your system. If you'd prefer Cosmopolitan, just add
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$(LIBC) and $(CRT) to your linker arguments.
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Your library is compromised of many bite-sized static archives.
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We use the checkdeps tool to guarantee that the contents of the
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archives are organized in a logical way that's easy to use with
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or without our makefile infrastructure, since there's no cyclic
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dependencies.
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The Cosmopolitan Library exports only the most stable canonical
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system calls for all supported operating systems, regardless of
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which platform is used for compilation. We polyfill many of the
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APIs, e.g. read(), write() so they work consistently everywhere
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while other apis, e.g. CreateWindowEx(), might only work on one
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platform, in which case they become no-op functions on others.
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Cosmopolitan polyfill wrappers will usually use the dollar sign
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naming convention, so they may be bypassed when necessary. This
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same convention is used when multiple implementations of string
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library and other performance-critical function are provided to
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allow Cosmopolitan to go fast on both old and newer computers.
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We take an approach to configuration that relies heavily on the
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compiler's dead code elimination pass (libc/dce.h). Most of the
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code is written so that, for example, folks not wanting support
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for OpenBSD can flip a bit in SUPPORT_VECTOR and that code will
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be omitted from the build. The same is true for builds that are
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tuned using -march=native which effectively asks the library to
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not include runtime support hooks for x86 processors older than
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what you use.
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Please note that, unlike Cygwin or MinGW, Cosmopolitan does not
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achieve broad support by bolting on a POSIX emulation layer. We
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do nothing more than (in most cases) stateless API translations
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that get you 90% of the way there in a fast lightweight manner.
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We therefore can't address some of the subtle differences, such
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as the nuances of absolute paths on Windows. Our approach could
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be compared to something more along the lines of, "the Russians
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just used a pencil to write in space", versus spending millions
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researching a pen like NASA.
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