• README

  • This directory contains the libffi package, which is not part of GCC but
    shipped with GCC as convenience.
    
    Status
    ======
    
    libffi-3.0.8 was released on December 19, 2008. Check the libffi web
    page for updates: <URL:http://sourceware.org/libffi/>.
    
    
    What is libffi?
    ===============
    
    Compilers for high level languages generate code that follow certain
    conventions. These conventions are necessary, in part, for separate
    compilation to work. One such convention is the "calling
    convention". The "calling convention" is essentially a set of
    assumptions made by the compiler about where function arguments will
    be found on entry to a function. A "calling convention" also specifies
    where the return value for a function is found.
    
    Some programs may not know at the time of compilation what arguments
    are to be passed to a function. For instance, an interpreter may be
    told at run-time about the number and types of arguments used to call
    a given function. Libffi can be used in such programs to provide a
    bridge from the interpreter program to compiled code.
    
    The libffi library provides a portable, high level programming
    interface to various calling conventions. This allows a programmer to
    call any function specified by a call interface description at run
    time.  
    
    FFI stands for Foreign Function Interface.  A foreign function
    interface is the popular name for the interface that allows code
    written in one language to call code written in another language. The
    libffi library really only provides the lowest, machine dependent
    layer of a fully featured foreign function interface. A layer must
    exist above libffi that handles type conversions for values passed
    between the two languages.
    
    
    Supported Platforms
    ===================
    
    Libffi has been ported to many different platforms, although this
    release was only tested on:
    
         arm oabi linux
         arm eabi linux
         hppa linux
         mips o32 linux (little endian)
         powerpc darwin
         powerpc freebsd
         powerpc64 linux
         sparc solaris
         sparc64 freebsd
         sparc64 solaris
         x86 cygwin
         x86 darwin
         x86 freebsd
         x86 linux
         x86 openbsd
         x86 solaris
         x86-64 mingw
         x86-64 darwin
         x86-64 linux
         x86-64 OS X
         x86-64 freebsd
         x86-64 solaris
         
    Please send additional platform test results to
    libffi-discuss@sourceware.org.
    
    Installing libffi
    =================
    
    [Note: before actually performing any of these installation steps,
     you may wish to read the "Platform Specific Notes" below.]
    
    First you must configure the distribution for your particular
    system. Go to the directory you wish to build libffi in and run the
    "configure" program found in the root directory of the libffi source
    distribution.
    
    You may want to tell configure where to install the libffi library and
    header files. To do that, use the --prefix configure switch.  Libffi
    will install under /usr/local by default. 
    
    If you want to enable extra run-time debugging checks use the the
    --enable-debug configure switch. This is useful when your program dies
    mysteriously while using libffi. 
    
    Another useful configure switch is --enable-purify-safety. Using this
    will add some extra code which will suppress certain warnings when you
    are using Purify with libffi. Only use this switch when using 
    Purify, as it will slow down the library.
    
    Configure has many other options. Use "configure --help" to see them all.
    
    Once configure has finished, type "make". Note that you must be using
    GNU make.  You can ftp GNU make from prep.ai.mit.edu:/pub/gnu.
    
    To ensure that libffi is working as advertised, type "make check".
    This will require that you have DejaGNU installed.
    
    To install the library and header files, type "make install".
    
    
    Platform Specific Notes
    =======================
    
    	MIPS - Irix 5.3 & 6.x
    	---------------------
    
    Irix 6.2 and better supports three different calling conventions: o32,
    n32 and n64. Currently, libffi only supports both o32 and n32 under
    Irix 6.x, but only o32 under Irix 5.3. Libffi will automatically be
    configured for whichever calling convention it was built for.
    
    By default, the configure script will try to build libffi with the GNU
    development tools. To build libffi with the SGI development tools, set
    the environment variable CC to either "cc -32" or "cc -n32" before
    running configure under Irix 6.x (depending on whether you want an o32
    or n32 library), or just "cc" for Irix 5.3.
    
    With the n32 calling convention, when returning structures smaller
    than 16 bytes, be sure to provide an RVALUE that is 8 byte aligned.
    Here's one way of forcing this:
    
    	double struct_storage[2];
    	my_small_struct *s = (my_small_struct *) struct_storage;  
    	/* Use s for RVALUE */
    
    If you don't do this you are liable to get spurious bus errors. 
    
    "long long" values are not supported yet.
    
    You must use GNU Make to build libffi on SGI platforms.
    
    
    	PowerPC System V ABI
    	--------------------
    
    There are two `System V ABI's which libffi implements for PowerPC.
    They differ only in how small structures are returned from functions.
    
    In the FFI_SYSV version, structures that are 8 bytes or smaller are
    returned in registers.  This is what GCC does when it is configured
    for solaris, and is what the System V ABI I have (dated September
    1995) says.
    
    In the FFI_GCC_SYSV version, all structures are returned the same way:
    by passing a pointer as the first argument to the function.  This is
    what GCC does when it is configured for linux or a generic sysv
    target.
    
    EGCS 1.0.1 (and probably other versions of EGCS/GCC) also has a
    inconsistency with the SysV ABI: When a procedure is called with many
    floating-point arguments, some of them get put on the stack.  They are
    all supposed to be stored in double-precision format, even if they are
    only single-precision, but EGCS stores single-precision arguments as
    single-precision anyway.  This causes one test to fail (the `many
    arguments' test).
    
    
    History
    =======
    
    3.0.7 Nov-11-08
            Fix for ppc FreeBSD.
    	(thanks to Andreas Tobler)
    
    3.0.6 Jul-17-08
            Fix for closures on sh.
    	Mark the sh/sh64 stack as non-executable.
    	(both thanks to Kaz Kojima)
    
    3.0.5 Apr-3-08
            Fix libffi.pc file.
    	Fix #define ARM for IcedTea users.
    	Fix x86 closure bug.
    
    3.0.4 Feb-24-08
            Fix x86 OpenBSD configury.
    
    3.0.3 Feb-22-08
            Enable x86 OpenBSD thanks to Thomas Heller, and
    	x86-64 FreeBSD thanks to Björn König and Andreas Tobler.
    	Clean up test instruction in README.
    
    3.0.2 Feb-21-08
            Improved x86 FreeBSD support.
    	Thanks to Björn König.
    
    3.0.1 Feb-15-08
            Fix instruction cache flushing bug on MIPS.
    	Thanks to David Daney.
    
    3.0.0 Feb-15-08
            Many changes, mostly thanks to the GCC project.
    	Cygnus Solutions is now Red Hat.
    
      [10 years go by...]
    
    1.20 Oct-5-98
    	Raffaele Sena produces ARM port.
    
    1.19 Oct-5-98
    	Fixed x86 long double and long long return support.
    	m68k bug fixes from Andreas Schwab.
    	Patch for DU assembler compatibility for the Alpha from Richard
    	Henderson.
    
    1.18 Apr-17-98
    	Bug fixes and MIPS configuration changes.
    
    1.17 Feb-24-98
    	Bug fixes and m68k port from Andreas Schwab. PowerPC port from
    	Geoffrey Keating. Various bug x86, Sparc and MIPS bug fixes.
    
    1.16 Feb-11-98
    	Richard Henderson produces Alpha port.
    
    1.15 Dec-4-97
    	Fixed an n32 ABI bug. New libtool, auto* support.
    
    1.14 May-13-97
    	libtool is now used to generate shared and static libraries.
    	Fixed a minor portability problem reported by Russ McManus
    	<mcmanr@eq.gs.com>.
    
    1.13 Dec-2-96
    	Added --enable-purify-safety to keep Purify from complaining
    	about certain low level code.
    	Sparc fix for calling functions with < 6 args.
    	Linux x86 a.out fix.
    
    1.12 Nov-22-96
    	Added missing ffi_type_void, needed for supporting void return 
    	types. Fixed test case for non MIPS machines. Cygnus Support 
    	is now Cygnus Solutions. 
    
    1.11 Oct-30-96
    	Added notes about GNU make.
    
    1.10 Oct-29-96
    	Added configuration fix for non GNU compilers.
    
    1.09 Oct-29-96
    	Added --enable-debug configure switch. Clean-ups based on LCLint 
    	feedback. ffi_mips.h is always installed. Many configuration 
    	fixes. Fixed ffitest.c for sparc builds.
    
    1.08 Oct-15-96
    	Fixed n32 problem. Many clean-ups.
    
    1.07 Oct-14-96
    	Gordon Irlam rewrites v8.S again. Bug fixes.
    
    1.06 Oct-14-96
    	Gordon Irlam improved the sparc port. 
    
    1.05 Oct-14-96
    	Interface changes based on feedback.
    
    1.04 Oct-11-96
    	Sparc port complete (modulo struct passing bug).
    
    1.03 Oct-10-96
    	Passing struct args, and returning struct values works for
    	all architectures/calling conventions. Expanded tests.
    
    1.02 Oct-9-96
    	Added SGI n32 support. Fixed bugs in both o32 and Linux support.
    	Added "make test".
    
    1.01 Oct-8-96
    	Fixed float passing bug in mips version. Restructured some
    	of the code. Builds cleanly with SGI tools.
    
    1.00 Oct-7-96
    	First release. No public announcement.
    
    
    Authors & Credits
    =================
    
    libffi was originally written by Anthony Green <green@redhat.com>.
    
    The developers of the GNU Compiler Collection project have made
    innumerable valuable contributions.  See the ChangeLog file for
    details.
    
    Some of the ideas behind libffi were inspired by Gianni Mariani's free
    gencall library for Silicon Graphics machines.
    
    The closure mechanism was designed and implemented by Kresten Krab
    Thorup.
    
    Major processor architecture ports were contributed by the following
    developers:
    
    alpha		Richard Henderson
    arm		Raffaele Sena
    cris		Simon Posnjak, Hans-Peter Nilsson
    frv		Anthony Green
    ia64		Hans Boehm
    m32r		Kazuhiro Inaoka
    m68k		Andreas Schwab
    mips		Anthony Green, Casey Marshall
    mips64		David Daney
    pa		Randolph Chung, Dave Anglin, Andreas Tobler
    powerpc		Geoffrey Keating, Andreas Tobler, 
    			 David Edelsohn, John Hornkvist
    powerpc64	Jakub Jelinek
    s390		Gerhard Tonn, Ulrich Weigand
    sh		Kaz Kojima
    sh64		Kaz Kojima
    sparc		Anthony Green, Gordon Irlam
    x86		Anthony Green, Jon Beniston
    x86-64		Bo Thorsen
    
    Jesper Skov and Andrew Haley both did more than their fair share of
    stepping through the code and tracking down bugs.
    
    Thanks also to Tom Tromey for bug fixes, documentation and
    configuration help.
    
    Thanks to Jim Blandy, who provided some useful feedback on the libffi
    interface.
    
    Andreas Tobler has done a tremendous amount of work on the testsuite.
    
    Alex Oliva solved the executable page problem for SElinux.
    
    The list above is almost certainly incomplete and inaccurate.  I'm
    happy to make corrections or additions upon request.
    
    If you have a problem, or have found a bug, please send a note to
    green@redhat.com.