Status

======

libffi-3.0.5 was released on April 3, 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 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

     powerpc64 linux

     sparc solaris

     sparc64 solaris

     x86 cygwin

     x86 darwin

     x86 freebsd

     x86 linux

     x86 openbsd

     x86-64 darwin

     x86-64 linux

     x86-64 OS X

     x86-64 freebsd

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

=======

3.0.5 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.