| 1 | This directory contains the libffi package, which is not part of GCC but
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| 2 | shipped with GCC as convenience.
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| 3 |
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| 4 | Status
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| 5 | ======
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| 6 |
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| 7 | libffi-2.00 has not been released yet! This is a development snapshot!
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| 8 |
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| 9 | libffi-1.20 was released on October 5, 1998. Check the libffi web
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| 10 | page for updates: <URL:http://sources.redhat.com/libffi/>.
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| 11 |
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| 12 |
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| 13 | What is libffi?
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| 14 | ===============
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| 15 |
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| 16 | Compilers for high level languages generate code that follow certain
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| 17 | conventions. These conventions are necessary, in part, for separate
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| 18 | compilation to work. One such convention is the "calling
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| 19 | convention". The "calling convention" is essentially a set of
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| 20 | assumptions made by the compiler about where function arguments will
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| 21 | be found on entry to a function. A "calling convention" also specifies
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| 22 | where the return value for a function is found.
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| 23 |
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| 24 | Some programs may not know at the time of compilation what arguments
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| 25 | are to be passed to a function. For instance, an interpreter may be
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| 26 | told at run-time about the number and types of arguments used to call
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| 27 | a given function. Libffi can be used in such programs to provide a
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| 28 | bridge from the interpreter program to compiled code.
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| 29 |
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| 30 | The libffi library provides a portable, high level programming
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| 31 | interface to various calling conventions. This allows a programmer to
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| 32 | call any function specified by a call interface description at run
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| 33 | time.
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| 34 |
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| 35 | Ffi stands for Foreign Function Interface. A foreign function
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| 36 | interface is the popular name for the interface that allows code
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| 37 | written in one language to call code written in another language. The
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| 38 | libffi library really only provides the lowest, machine dependent
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| 39 | layer of a fully featured foreign function interface. A layer must
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| 40 | exist above libffi that handles type conversions for values passed
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| 41 | between the two languages.
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| 42 |
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| 43 |
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| 44 | Supported Platforms and Prerequisites
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| 45 | =====================================
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| 46 |
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| 47 | Libffi has been ported to:
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| 48 |
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| 49 | SunOS 4.1.3 & Solaris 2.x (Sparc v8)
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| 50 |
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| 51 | Irix 5.3 & 6.2 (System V/o32 & n32)
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| 52 |
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| 53 | Intel x86 - Linux (System V ABI)
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| 54 |
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| 55 | Alpha - Linux and OSF/1
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| 56 |
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| 57 | m68k - Linux (System V ABI)
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| 58 |
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| 59 | PowerPC - Linux (System V ABI, Darwin, AIX)
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| 60 |
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| 61 | ARM - Linux (System V ABI)
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| 62 |
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| 63 | Libffi has been tested with the egcs 1.0.2 gcc compiler. Chances are
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| 64 | that other versions will work. Libffi has also been built and tested
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| 65 | with the SGI compiler tools.
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| 66 |
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| 67 | On PowerPC, the tests failed (see the note below).
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| 68 |
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| 69 | You must use GNU make to build libffi. SGI's make will not work.
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| 70 | Sun's probably won't either.
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| 71 |
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| 72 | If you port libffi to another platform, please let me know! I assume
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| 73 | that some will be easy (x86 NetBSD), and others will be more difficult
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| 74 | (HP).
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| 75 |
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| 76 |
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| 77 | Installing libffi
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| 78 | =================
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| 79 |
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| 80 | [Note: before actually performing any of these installation steps,
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| 81 | you may wish to read the "Platform Specific Notes" below.]
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| 82 |
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| 83 | First you must configure the distribution for your particular
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| 84 | system. Go to the directory you wish to build libffi in and run the
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| 85 | "configure" program found in the root directory of the libffi source
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| 86 | distribution.
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| 87 |
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| 88 | You may want to tell configure where to install the libffi library and
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| 89 | header files. To do that, use the --prefix configure switch. Libffi
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| 90 | will install under /usr/local by default.
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| 91 |
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| 92 | If you want to enable extra run-time debugging checks use the the
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| 93 | --enable-debug configure switch. This is useful when your program dies
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| 94 | mysteriously while using libffi.
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| 95 |
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| 96 | Another useful configure switch is --enable-purify-safety. Using this
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| 97 | will add some extra code which will suppress certain warnings when you
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| 98 | are using Purify with libffi. Only use this switch when using
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| 99 | Purify, as it will slow down the library.
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| 100 |
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| 101 | Configure has many other options. Use "configure --help" to see them all.
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| 102 |
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| 103 | Once configure has finished, type "make". Note that you must be using
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| 104 | GNU make. SGI's make will not work. Sun's probably won't either.
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| 105 | You can ftp GNU make from prep.ai.mit.edu:/pub/gnu.
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| 106 |
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| 107 | To ensure that libffi is working as advertised, type "make test".
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| 108 |
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| 109 | To install the library and header files, type "make install".
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| 110 |
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| 111 |
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| 112 | Using libffi
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| 113 | ============
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| 114 |
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| 115 | The Basics
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