4 libffi-3.0.5 was released on April 3, 2008. Check the libffi web
5 page for updates: <URL:http://sourceware.org/libffi/>.
11 Compilers for high level languages generate code that follow certain
12 conventions. These conventions are necessary, in part, for separate
13 compilation to work. One such convention is the "calling convention".
14 The "calling convention" is a set of assumptions made by the compiler
15 about where function arguments will be found on entry to a function.
16 A "calling convention" also specifies where the return value for a
19 Some programs may not know at the time of compilation what arguments
20 are to be passed to a function. For instance, an interpreter may be
21 told at run-time about the number and types of arguments used to call
22 a given function. Libffi can be used in such programs to provide a
23 bridge from the interpreter program to compiled code.
25 The libffi library provides a portable, high level programming
26 interface to various calling conventions. This allows a programmer to
27 call any function specified by a call interface description at run
30 FFI stands for Foreign Function Interface. A foreign function
31 interface is the popular name for the interface that allows code
32 written in one language to call code written in another language. The
33 libffi library really only provides the lowest, machine dependent
34 layer of a fully featured foreign function interface. A layer must
35 exist above libffi that handles type conversions for values passed
36 between the two languages.
42 Libffi has been ported to many different platforms, although this
43 release was only tested on:
48 mips o32 linux (little endian)
63 Please send additional platform test results to
64 libffi-discuss@sourceware.org.
69 [Note: before actually performing any of these installation steps,
70 you may wish to read the "Platform Specific Notes" below.]
72 First you must configure the distribution for your particular
73 system. Go to the directory you wish to build libffi in and run the
74 "configure" program found in the root directory of the libffi source
77 You may want to tell configure where to install the libffi library and
78 header files. To do that, use the --prefix configure switch. Libffi
79 will install under /usr/local by default.
81 If you want to enable extra run-time debugging checks use the the
82 --enable-debug configure switch. This is useful when your program dies
83 mysteriously while using libffi.
85 Another useful configure switch is --enable-purify-safety. Using this
86 will add some extra code which will suppress certain warnings when you
87 are using Purify with libffi. Only use this switch when using
88 Purify, as it will slow down the library.
90 Configure has many other options. Use "configure --help" to see them all.
92 Once configure has finished, type "make". Note that you must be using
93 GNU make. You can ftp GNU make from prep.ai.mit.edu:/pub/gnu.
95 To ensure that libffi is working as advertised, type "make check".
96 This will require that you have DejaGNU installed.
98 To install the library and header files, type "make install".
101 Platform Specific Notes
102 =======================
104 MIPS - Irix 5.3 & 6.x
105 ---------------------
107 Irix 6.2 and better supports three different calling conventions: o32,
108 n32 and n64. Currently, libffi only supports both o32 and n32 under
109 Irix 6.x, but only o32 under Irix 5.3. Libffi will automatically be
110 configured for whichever calling convention it was built for.
112 By default, the configure script will try to build libffi with the GNU
113 development tools. To build libffi with the SGI development tools, set
114 the environment variable CC to either "cc -32" or "cc -n32" before
115 running configure under Irix 6.x (depending on whether you want an o32
116 or n32 library), or just "cc" for Irix 5.3.
118 With the n32 calling convention, when returning structures smaller
119 than 16 bytes, be sure to provide an RVALUE that is 8 byte aligned.
120 Here's one way of forcing this:
122 double struct_storage[2];
123 my_small_struct *s = (my_small_struct *) struct_storage;
124 /* Use s for RVALUE */
126 If you don't do this you are liable to get spurious bus errors.
128 "long long" values are not supported yet.
130 You must use GNU Make to build libffi on SGI platforms.
136 There are two `System V ABI's which libffi implements for PowerPC.
137 They differ only in how small structures are returned from functions.
139 In the FFI_SYSV version, structures that are 8 bytes or smaller are
140 returned in registers. This is what GCC does when it is configured
141 for solaris, and is what the System V ABI I have (dated September
144 In the FFI_GCC_SYSV version, all structures are returned the same way:
145 by passing a pointer as the first argument to the function. This is
146 what GCC does when it is configured for linux or a generic sysv
149 EGCS 1.0.1 (and probably other versions of EGCS/GCC) also has a
150 inconsistency with the SysV ABI: When a procedure is called with many
151 floating-point arguments, some of them get put on the stack. They are
152 all supposed to be stored in double-precision format, even if they are
153 only single-precision, but EGCS stores single-precision arguments as
154 single-precision anyway. This causes one test to fail (the `many
163 Fix #define ARM for IcedTea users.
167 Fix x86 OpenBSD configury.
170 Enable x86 OpenBSD thanks to Thomas Heller, and
171 x86-64 FreeBSD thanks to Björn König and Andreas Tobler.
172 Clean up test instruction in README.
175 Improved x86 FreeBSD support.
176 Thanks to Björn König.
179 Fix instruction cache flushing bug on MIPS.
180 Thanks to David Daney.
183 Many changes, mostly thanks to the GCC project.
184 Cygnus Solutions is now Red Hat.
189 Raffaele Sena produces ARM port.
192 Fixed x86 long double and long long return support.
193 m68k bug fixes from Andreas Schwab.
194 Patch for DU assembler compatibility for the Alpha from Richard
198 Bug fixes and MIPS configuration changes.
201 Bug fixes and m68k port from Andreas Schwab. PowerPC port from
202 Geoffrey Keating. Various bug x86, Sparc and MIPS bug fixes.
205 Richard Henderson produces Alpha port.
208 Fixed an n32 ABI bug. New libtool, auto* support.
211 libtool is now used to generate shared and static libraries.
212 Fixed a minor portability problem reported by Russ McManus
216 Added --enable-purify-safety to keep Purify from complaining
217 about certain low level code.
218 Sparc fix for calling functions with < 6 args.
222 Added missing ffi_type_void, needed for supporting void return
223 types. Fixed test case for non MIPS machines. Cygnus Support
224 is now Cygnus Solutions.
227 Added notes about GNU make.
230 Added configuration fix for non GNU compilers.
233 Added --enable-debug configure switch. Clean-ups based on LCLint
234 feedback. ffi_mips.h is always installed. Many configuration
235 fixes. Fixed ffitest.c for sparc builds.
238 Fixed n32 problem. Many clean-ups.
241 Gordon Irlam rewrites v8.S again. Bug fixes.
244 Gordon Irlam improved the sparc port.
247 Interface changes based on feedback.
250 Sparc port complete (modulo struct passing bug).
253 Passing struct args, and returning struct values works for
254 all architectures/calling conventions. Expanded tests.
257 Added SGI n32 support. Fixed bugs in both o32 and Linux support.
261 Fixed float passing bug in mips version. Restructured some
262 of the code. Builds cleanly with SGI tools.
265 First release. No public announcement.
271 libffi was originally written by Anthony Green <green@redhat.com>.
273 The developers of the GNU Compiler Collection project have made
274 innumerable valuable contributions. See the ChangeLog file for
277 Some of the ideas behind libffi were inspired by Gianni Mariani's free
278 gencall library for Silicon Graphics machines.
280 The closure mechanism was designed and implemented by Kresten Krab
283 Major processor architecture ports were contributed by the following
286 alpha Richard Henderson
288 cris Simon Posnjak, Hans-Peter Nilsson
293 mips Anthony Green, Casey Marshall
295 pa Randolph Chung, Dave Anglin, Andreas Tobler
296 powerpc Geoffrey Keating, Andreas Tobler,
297 David Edelsohn, John Hornkvist
298 powerpc64 Jakub Jelinek
299 s390 Gerhard Tonn, Ulrich Weigand
302 sparc Anthony Green, Gordon Irlam
303 x86 Anthony Green, Jon Beniston
306 Jesper Skov and Andrew Haley both did more than their fair share of
307 stepping through the code and tracking down bugs.
309 Thanks also to Tom Tromey for bug fixes, documentation and
312 Thanks to Jim Blandy, who provided some useful feedback on the libffi
315 Andreas Tobler has done a tremendous amount of work on the testsuite.
317 Alex Oliva solved the executable page problem for SElinux.
319 The list above is almost certainly incomplete and inaccurate. I'm
320 happy to make corrections or additions upon request.
322 If you have a problem, or have found a bug, please send a note to