Gambit-list Juillet 2008

gambit-list@iro.umontreal.ca

14 participants
15 discussions

Edge triggered I/O with libevent
by Adam Langley 04 Avr '13

04 Avr '13

Gambit uses the select call on POSIX systems to multiplex IO operations. This is fine for small numbers of file descriptors, but falls apart quickly with large numbers[1]. libevent[2] is a wrapper library around a number of modern IO multiplexing systems (epoll on Linux, kqueue on the BSDs as well as poll and select). Attached is a patch which converts Gambit to using edge triggered I/O with epoll and libevent. This also requires a patch (attached) of libevent since the standard distribution doesn't include edge triggering support and the upstream appears to be on holiday. (epoll is required because I don't have a BSD box on which to develop edge triggering support for kqueue) This patch (for Gambit) preprocesses away to nothing unless --enable-libevent is passed to the configure script. (Note that, since this patches the configure.ac script, you'll need to run autoconf to regenerate). I hope I've not broken anything, but at this stage I've only tested that the console and tcp ports work. This patch (in the future) should also allow people, who write programs which use socket calls directly, to integrate into the main event loop at some point. Testing is more than welcome and, if you find a form of IO which is broken, please email me. [1] http://monkey.org/~provos/libevent/libevent-benchmark2.jpg [2] http://monkey.org/~provos/libevent/ -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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Space Invaders on gambit-c
by David St-Hilaire 21 Aoû '08

21 Aoû '08

Hi all! I just wanted to let you know that I've just put my space invaders (the classic arcade game) re-make on the dumping grounds. There are also pre-compiled binaries available on my web page (http://www-etud.iro.umontreal.ca/~sthilaid/). The game runs over glut and SDL and should be compatible at least with linux, windows and mac systems (execpt that the glut user interface does not seem to work in windows...). Compilation insights is provided in the README file. Just send me a mail for help, question, comments, or most likely, bug reports! ;) Enjoy! ^_^Y David

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What is the best strategy to ensure that non-FFI code can never cause sigsegv:s / bus errors?
by Mikael More 14 Aoû '08

14 Aoû '08

Hi! We're having limited problems with our Gambit software throwing sigsegvs / bus errors, on x86 debian and on mac os x. The instances we see that we have had sigsegvs / bus errors in are: - when using #!unbound or #!void values in code compiled with (declare (not safe)) - when not catching exceptions (like in the example below) - immediately following C calls from Scheme, where the C code makes callbacks back into Scheme, though these errors may be due to us using broken FFI code. What are the best strategies to ensure that non-FFI code can never cause sigsegv:s / bus errors? ( I suppose for starters, it is not to override the default (declare (safe)) declaration. What more? ) Thanks Mikael - The following example produces sigsegv undepending on if compiled with gcc or g++. Executing (termite#spawn (lambda () (raise "hi"))) works as expected, it does not throw any sigsegv. debian:~/main$ gdb gsc GNU gdb 6.4.90-debian Copyright (C) 2006 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i486-linux-gnu"...Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1". (gdb) run Starting program: /usr/bin/gsc Failed to read a valid object file image from memory. Gambit v4.2.8 > (load "~~/lib/termite/termite") "/usr/local/Gambit-C/v4.2.8/lib/termite/termite.o1" > (termite#node-init (termite#make-node "127.0.0.1" 3000)) ok > (termite#spawn (lambda () (raise "hi"))) #<thread #2> > Program received signal SIGSEGV, Segmentation fault. 0x08220202 in ___H__20___kernel () (gdb) bt #0 0x08220202 in ___H__20___kernel () #1 0x00000000 in ?? ()

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getting symbol table
by Nguyen Thai Ngoc Duy 31 Jul '08

31 Jul '08

Hi, Is there any way to get global symbol table from scheme? (Because I see that symbol completion is done in C). -- Duy

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Structs in FFI
by Ken Dickey 25 Jul '08

25 Jul '08

Hi, There is and example of getting struct parameters in the current GUI-Toy version in "sdl-interface.scm". =============IN PROCESS FYI================ [YOU CAN SKIP THIS] FYI, one of the things I am looking at is the difference between direct FFI calls and using a pipe to a sub-process. The "pipe" interface allows for rapid porting (currently GUI-Toy runs on Gambit, Larceny, PLT, Ypsilon, Chez, and Ikarus Schemes). To make adding calls easy, I have started a declarative "FFI" which writes both the Scheme and C code. (describe-interface ; ... (describe-call (Scheme SDL::load-bmp-file (file-name-string char*)) (C "SDL_LoadBMP" (file-name-string) (pointer "SDL_Surface"))) (describe-c-struct SDL_Rect (x Sint16) (y Sint16) (w Uint16) (h Uint16)) (describe-access (SDL_Rect rectangle?) ; (c-field-name scheme-getter-name) ... (x x) (y y) (w width) (h height)) (describe-call (Scheme SDL::draw-rect (surface (pointer "SDL_Surface")) (rect (access rectangle? SDL_Rect)) (rgb-color Uint32)) (C "SDL_FillRect" (surface rect rgb-color) void)) ;... ) The generated Scheme code does basic error checks and reporting, puts out a shared call tag/id, and accesses object fields to "spread" the values for the "call". (define (SDL::draw-rect surface rect rgb-color) (unless (Uint32? surface) (report-arg-check-error 'SDL::draw-rect 'surface 'Uint32?)) (unless (rectangle? rect) (report-arg-check-error 'SDL::draw-rect 'rect 'rectangle?)) (unless (Uint32? rgb-color) (report-arg-check-error 'SDL::draw-rect 'rgb-color 'Uint32?)) (put-Uint8 port->sdl 34) ; call tag (put-Uint32 port->sdl surface) (put-Sint16 port->sdl [$ x rect]) (put-Sint16 port->sdl [$ y rect]) (put-Uint16 port->sdl [$ width rect]) (put-Uint16 port->sdl [$ height rect]) (put-Uint32 port->sdl rgb-color) (flush-output-port port->sdl) ) The generated C code dispatches on the call tag, stack allocates temporaries, makes the SDL call, and returns a result as required. case (char)(34): { /* SDL::draw-rect -> SDL_FillRect */ unsigned char buf[16]; read(fileno(stdin), buf, 16); int offset = 0 ; /* surface */ Uint32 surface = getUint32( buf, offset ) ; offset += sizeof( Uint32 ) ; /* rect */ SDL_Rect rect ; rect.x = getSint16(buf, offset) ; offset += sizeof( Sint16 ) ; rect.y = getSint16(buf, offset) ; offset += sizeof( Sint16 ) ; rect.w = getUint16(buf, offset) ; offset += sizeof( Uint16 ) ; rect.h = getUint16(buf, offset) ; offset += sizeof( Uint16 ) ; /* rgb-color */ Uint32 rgb_color = getUint32( buf, offset ) ; offset += sizeof( Uint32 ) ; SDL_FillRect( (SDL_Surface*)(surface), &(rect), rgb_color ); } break; I hope at some point to gen both "Scheme native" FFI and the "pipe call" interface. NYI. This is all stuff in progress, not ready for prime time, but may give you some ideas. I plan to report on things at the upcoming Scheme Workshop in Victoria, BC. If you happen to get there, perhaps we can chat. Cheers, -KenD

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Structs in FFI
by Will Donnelly 25 Jul '08

25 Jul '08

Recently (this morning) I began using Gambit Scheme, and so far it has been a wonderful language to work with. I like doing graphical stuff, so I'm trying to use Gambit's FFI to interface with the SDL libraries. I've gotten everything to work so far, compiling and linking with libSDL from within gsc properly, but now I have two questions. One, is there any way to specify, in comments or some such, what compiler and linker flags a file should have in a call to compile-file? I'm using emacs as an editor, and the C-c C-k command is useless, since the file won't get linked to libSDL like it needs to. This is really only a minor issue though, as (begin (compile-file "sdl-test" ld-options: "-lSDL") (load "sdl-test")) is not too hard to use. Two, am I missing something when it comes to interfacing with C structs? The only references that I've found (http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php/Using_Gambit_with_Ext…) and (http://www.iro.umontreal.ca/~gambit/doc/gambit-c.html#SEC135) seem to contain horrendously complex code for something as simple as accessing a struct like typedef struct SDL_Rect { Sint16 x, y; Uint16 w, h; } SDL_Rect; from within Scheme. Does anyone with more experience than I have some pointers on how to do this?

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[ANN] Intelligent WTF 0.001
by adamsonj＠email.unc.edu 17 Jul '08

17 Jul '08

Intelligent WTF Based on BSD Games' WTF Written in the Gambit-C implementation of Scheme Copyright (C) 2008 Joel J. Adamson Intelligent WTF is free software distributed under the GNU General Public License Version 3 Intelligent WTF is an acronym decoder: it uses a central database to store internet/hacker slang (now commonly used in email and text messaging: e.g., "lol"). NetBSD includes a game called WTF that decodes acronyms on the command line; Intelligent WTF improves on this by adding an interactive mode (batch mode not yet implemented), acronym and synonym learning, editing the acronyms file, and a built-in Scheme interpreter for extensions and customizations. * Obtaining Intelligent WTF Intelligent WTF is available from its author's homepage: http://www.unc.edu/~adamonsj/files/iwtf.tar.gz You may browse the source code at http://www.unc.edu/~adamonsj/files/iwtf * Problems? Suggestions? Report bugs to sparrow1240(a)gmail.com with as much information as you can. Please include a transcript of your iwtf session, your .acronyms file, and your operating system, shell and anything else you think might be important. See the TODO for a list of planned features. Suggestions are welcome and code contributions are encouraged. Future plans include: a full grammar for suggesting and combining acronyms and slang, searching by keyword and meaning (pattern matching). Collaboration is greatly appreciated. **Note: this software previously released to http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php/Dumping_Grounds -- Joel J. Adamson Public key: http://pgp.mit.edu http://www.unc.edu/~adamsonj http://trashbird1240.blogspot.com

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Termite moved to Google Code
by Guillaume Germain 14 Jul '08

14 Jul '08

Hi, I've moved Termite to Google Code. It is now accessible here: http://code.google.com/p/termite/ Hopefully, this will make it easier to file issues, track changes, collaborate, document stuff on the Wiki, etc. Anybody who is willing to contribute should send me an email. Cheers, Guillaume

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Disabling keywords
by j.romildo＠gmail.com 12 Jul '08

12 Jul '08

Hello. Please, how can keywords be disable when compiling a Scheme program with the gambit compiler? José Romildo

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enable-single-host and gcc 4.2.3
by Jeremie Lasalle Ratelle 10 Jul '08

10 Jul '08

Hi, I just installed ubuntu 8.04 and it seems that gcc 4.2.3 isn't able to compile large files using --enable-single-host. We tried compiling a 6000 lines file and a 16000 lines file. (Generated from Jazz modules) Using enable-single-host, both of them are still compiling after 10 minutes. Without enable-single-host it takes 1 minute for the 6000 one and the 16000 one is still going on after 10 minutes. On Apple gcc 4.0.1 it takes 1.5 minute to compile the 16000 lines file with enable-single-host In windows on gcc-mingw-3.4.5 it takes about 20 seconds with enable-single-host. Could this be some serious regression?...

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Gambit-list Juillet 2008