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diff --git a/libffi/README b/libffi/README deleted file mode 100644 index 902e644cd24..00000000000 --- a/libffi/README +++ /dev/null @@ -1,505 +0,0 @@ -README for libffi-2.00 - -libffi-2.00 has not been released yet! This is a development snapshot! - -libffi-1.20 was released on [SOME FUTURE DAY]. Check the libffi web -page for updates: <URL:http://sourceware.cygnus.com/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 and Prerequisites -===================================== - -Libffi has been ported to: - - SunOS 4.1.3 & Solaris 2.x (Sparc v8) - - Irix 5.3 & 6.2 (System V/o32 & n32) - - Intel x86 - Linux (System V ABI) - - Alpha - Linux and OSF/1 - - m68k - Linux (System V ABI) - - PowerPC - Linux (System V ABI) - - ARM - Linux (System V ABI) - -Libffi has been tested with the egcs 1.0.2 gcc compiler. Chances are -that other versions will work. Libffi has also been built and tested -with the SGI compiler tools. - -On PowerPC, the tests failed (see the note below). - -You must use GNU make to build libffi. SGI's make will not work. -Sun's probably won't either. - -If you port libffi to another platform, please let me know! I assume -that some will be easy (x86 NetBSD), and others will be more difficult -(HP, AIX). - - -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. SGI's make will not work. Sun's probably won't either. -You can ftp GNU make from prep.ai.mit.edu:/pub/gnu. - -To ensure that libffi is working as advertised, type "make test". - -To install the library and header files, type "make install". - - -Using libffi -============ - - The Basics - ---------- - -Libffi assumes that you have a pointer to the function you wish to -call and that you know the number and types of arguments to pass it, -as well as the return type of the function. - -The first thing you must do is create an ffi_cif object that matches -the signature of the function you wish to call. The cif in ffi_cif -stands for Call InterFace. To prepare a call interface object, use the -following function: - -ffi_status ffi_prep_cif(ffi_cif *cif, ffi_abi abi, - unsigned int nargs, - ffi_type *rtype, ffi_type **atypes); - - CIF is a pointer to the call interface object you wish - to initialize. - - ABI is an enum that specifies the calling convention - to use for the call. FFI_DEFAULT_ABI defaults - to the system's native calling convention. Other - ABI's may be used with care. They are system - specific. - - NARGS is the number of arguments this function accepts. - libffi does not yet support vararg functions. - - RTYPE is a pointer to an ffi_type structure that represents - the return type of the function. Ffi_type objects - describe the types of values. libffi provides - ffi_type objects for many of the native C types: - signed int, unsigned int, signed char, unsigned char, - etc. There is also a pointer ffi_type object and - a void ffi_type. Use &ffi_type_void for functions that - don't return values. - - ATYPES is a vector of ffi_type pointers. ARGS must be NARGS long. - If NARGS is 0, this is ignored. - - -ffi_prep_cif will return a status code that you are responsible -for checking. It will be one of the following: - - FFI_OK - All is good. - - FFI_BAD_TYPEDEF - One of the ffi_type objects that ffi_prep_cif - came across is bad. - - -Before making the call, the VALUES vector should be initialized -with pointers to the appropriate argument values. - -To call the the function using the initialized ffi_cif, use the -ffi_call function: - -void ffi_call(ffi_cif *cif, void *fn, void *rvalue, void **avalues); - - CIF is a pointer to the ffi_cif initialized specifically - for this function. - - FN is a pointer to the function you want to call. - - RVALUE is a pointer to a chunk of memory that is to hold the - result of the function call. Currently, it must be - at least one word in size (except for the n32 version - under Irix 6.x, which must be a pointer to an 8 byte - aligned value (a long long). It must also be at least - word aligned (depending on the return type, and the - system's alignment requirements). If RTYPE is - &ffi_type_void, this is ignored. If RVALUE is NULL, - the return value is discarded. - - AVALUES is a vector of void* that point to the memory locations - holding the argument values for a call. - If NARGS is 0, this is ignored. - - -If you are expecting a return value from FN it will have been stored -at RVALUE. - - - - An Example - ---------- - -Here is a trivial example that calls puts() a few times. - - #include <stdio.h> - #include <ffi.h> - - int main() - { - ffi_cif cif; - ffi_type *args[1]; - void *values[1]; - char *s; - int rc; - - /* Initialize the argument info vectors */ - args[0] = &ffi_type_uint; - values[0] = &s; - - /* Initialize the cif */ - if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1, - &ffi_type_uint, args) == FFI_OK) - { - s = "Hello World!"; - ffi_call(&cif, puts, &rc, values); - /* rc now holds the result of the call to puts */ - - /* values holds a pointer to the function's arg, so to - call puts() again all we need to do is change the - value of s */ - s = "This is cool!"; - ffi_call(&cif, puts, &rc, values); - } - - return 0; - } - - - - Aggregate Types - --------------- - -Although libffi has no special support for unions or bit-fields, it is -perfectly happy passing structures back and forth. You must first -describe the structure to libffi by creating a new ffi_type object -for it. Here is the definition of ffi_type: - - typedef struct _ffi_type - { - unsigned size; - short alignment; - short type; - struct _ffi_type **elements; - } ffi_type; - -All structures must have type set to FFI_TYPE_STRUCT. You may set -size and alignment to 0. These will be calculated and reset to the -appropriate values by ffi_prep_cif(). - -elements is a NULL terminated array of pointers to ffi_type objects -that describe the type of the structure elements. These may, in turn, -be structure elements. - -The following example initializes a ffi_type object representing the -tm struct from Linux's time.h: - - struct tm { - int tm_sec; - int tm_min; - int tm_hour; - int tm_mday; - int tm_mon; - int tm_year; - int tm_wday; - int tm_yday; - int tm_isdst; - /* Those are for future use. */ - long int __tm_gmtoff__; - __const char *__tm_zone__; - }; - - { - ffi_type tm_type; - ffi_type *tm_type_elements[12]; - int i; - - tm_type.size = tm_type.alignment = 0; - tm_type.elements = &tm_type_elements; - - for (i = 0; i < 9; i++) - tm_type_elements[i] = &ffi_type_sint; - - tm_type_elements[9] = &ffi_type_slong; - tm_type_elements[10] = &ffi_type_pointer; - tm_type_elements[11] = NULL; - - /* tm_type can now be used to represent tm argument types and - return types for ffi_prep_cif() */ - } - - - -Platform Specific Notes -======================= - - Intel x86 - --------- - -There are no known problems with the x86 port. - - Sun Sparc - SunOS 4.1.3 & Solaris 2.x - ------------------------------------- - -There's a bug in the structure passing code for sparc processors. -Struct arguments that are passed in value actually end up being passed -by reference. This will be fixed Real Soon Now. - -"long long" values are not supported yet. - -You must use GNU Make to build libffi on Sun platforms. - - 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. - - ARM - System V ABI - ------------------ - -The ARM port was performed on a NetWinder running ARM Linux ELF -(2.0.31) and gcc 2.8.1. config.sub still does not recognize the -machine name sa110-unknown-linux-gnu (currently returned by -NetWinder). In the mean time the package can be configured by running -'configure arm-linux'. - - - - 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). - - -What's With The Crazy Comments? -=============================== - -You might notice a number of cryptic comments in the code, delimited -by /*@ and @*/. These are annotations read by the program LCLint, a -tool for statically checking C programs. You can read all about it at -<http://larch-www.lcs.mit.edu:8001/larch/lclint/index.html>. - - -History -======= - -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 written by Anthony Green <green@cygnus.com>. - -Portions of libffi were derived from Gianni Mariani's free gencall -library for Silicon Graphics machines. - -The closure mechanism was designed and implemented by Kresten Krab -Thorup. - -The Sparc port was derived from code contributed by the fine folks at -Visible Decisions Inc <http://www.vdi.com>. Further enhancements were -made by Gordon Irlam at Cygnus Solutions <http://www.cygnus.com>. - -The Alpha port was written by Richard Henderson at Cygnus Solutions. - -Andreas Schwab ported libffi to m68k Linux and provided a number of -bug fixes. - -Geoffrey Keating ported libffi to the PowerPC. - -Raffaele Sena ported libffi to the ARM. - -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 and configuration help. - -Thanks to Jim Blandy, who provided some useful feedback on the libffi -interface. - -If you have a problem, or have found a bug, please send a note to -green@cygnus.com. |