69 lines
3.3 KiB
Plaintext
69 lines
3.3 KiB
Plaintext
Sortix Math Library
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===================
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This is the Sortix Math Library (libm). It is a full implemention of the
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<complex.h>, <fenv.h>, <math.h>, and <tgmath.h> API as described in the C
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standard. A modern compiler should be able to build the library without any
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warnings as the code has been modernized. Some platforms have optimized versions
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of some functions available, but all functions are available as C code assuming
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IEEE floating point semantics.
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The library is a fork of the NetBSD 9.1 Math Library, with a few missing pieces
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taken from the NetBSD 9.1 libc and kernel. The code has been modified to be part
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of the Sortix operating system. However, we have tried to make as few changes to
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the source code files themselves, so it should be easy to upgrade this library
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if the upstream versions are upgraded as well. The internal header structure
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tries to be BSD-like so the code can include BSD headers provided internally.
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Some GNU extensions are implemented as well.
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License
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-------
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The library is partly public domain and partly BSD-style licensed, see the file
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LEGAL for information about which licenses are used. The files in this library
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carry their original copyright headers, although a few lack such headers and are
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assumed to carry the standard NetBSD license.
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Currently the e_exp.S file contains an advertisement clause from Winning
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Strategies, Inc., but otherwise the library is free of such requirements.
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Porting
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-------
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The source code is reasonable portable and compiles cleanly with gcc as C99,
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however the headers needs to be hooked up against the C library. As an example,
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they currently support Sortix libc and GNU libc. You will also want to redo the
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build system and probably fork the library. If you are the type that considers
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porting a libm, then you probably should be able to do it without too much pain.
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Standards Compliance
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--------------------
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There are two options in making libm at compile time:
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_IEEE_LIBM --- IEEE libm; smaller, and somewhat faster
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_MULTI_LIBM --- Support multi-standard at runtime by
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imposing wrapper functions defined in
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fdlibm.h:
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_IEEE_MODE -- IEEE
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_XOPEN_MODE -- X/OPEN
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_POSIX_MODE -- POSIX/ANSI
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_SVID3_MODE -- SVID
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Here is how to set up CPPFLAGS to create the desired libm at
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compile time:
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CPPFLAGS = -D_IEEE_LIBM ... IEEE libm (recommended)
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CPPFLAGS = -D_SVID3_MODE ... Multi-standard supported
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libm with SVID as the
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default standard
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CPPFLAGS = -D_XOPEN_MODE ... Multi-standard supported
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libm with XOPEN as the
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default standard
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CPPFLAGS = -D_POSIX_MODE ... Multi-standard supported
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libm with POSIX as the
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default standard
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CPPFLAGS = ... Multi-standard supported
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libm with IEEE as the
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default standard
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