Gambit-list Mai 2005

gambit-list@iro.umontreal.ca

11 participants
23 discussions

Struct alignment on Windows
by MichaelL＠frogware.com 15 Mai '05

15 Mai '05

The old Visual Studio make files force struct alignment to 4 bytes. Is that necessary today, or just a holdover from bygone days?

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Warnings Compiling Gambit Under Windows
by MichaelL＠frogware.com 15 Mai '05

15 Mai '05

Gambit is generating some warnings under Windows. Some of them look like real errors: 1 d:\tools\Scheme\proj\gambc40b13\lib\os_tty.c(7344) : warning C4113: 'BOOL (__stdcall *)()' differs in parameter lists from 'PHANDLER_ROUTINE' 2 d:\tools\Scheme\proj\gambc40b13\lib\os_tty.c(7362) : warning C4113: 'BOOL (__stdcall *)()' differs in parameter lists from 'PHANDLER_ROUTINE' 3 d:\tools\Scheme\proj\gambc40b13\lib\os_time.c(234) : warning C4307: '*' : integral constant overflow 4 d:\tools\Scheme\proj\gambc40b13\lib\os_time.c(234) : warning C4244: 'initializing' : conversion from 'LONGLONG' to 'int', possible loss of data 5 d:\tools\Scheme\proj\gambc40b13\lib\os_time.c(235) : warning C4244: 'initializing' : conversion from 'LONGLONG' to 'int', possible loss of data 6 d:\tools\Scheme\proj\gambc40b13\lib\os_time.c(1316) : warning C4113: 'DWORD (__stdcall *)()' differs in parameter lists from 'LPTHREAD_START_ROUTINE' 7 d:\tools\Scheme\proj\gambc40b13\lib\os_shell.c(177) : warning C4244: '=' : conversion from 'unsigned short' to 'char', possible loss of data 8 d:\tools\Scheme\proj\gambc40b13\lib\os_shell.c(444) : warning C4244: '=' : conversion from 'unsigned short' to 'char', possible loss of data 9 d:\tools\Scheme\proj\gambc40b13\lib\os_shell.c(466) : warning C4244: '=' : conversion from 'unsigned short' to 'char', possible loss of data 10 d:\tools\Scheme\proj\gambc40b13\lib\os_shell.c(594) : warning C4244: '=' : conversion from 'unsigned short' to 'char', possible loss of data 11 d:\tools\scheme\proj\gambc40b13\lib\os_io.c(5527) : warning C4700: local variable 'dev' used without having been initialized There are two other warnings that appear about 200 times building the library. I presume they're intentional: 12 d:\tools\Scheme\proj\gambc40b13\lib\_std.c(2011) : warning C4146: unary minus operator applied to unsigned type, result still unsigned 13 d:\tools\Scheme\proj\gambc40b13\lib\_std.c(21221) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data Here's an example of the first: ___BIGFIX1(-0x80000000L) Here's an example of the second: ___F32VECTORSET(___R1,___R3,___F64V1) ================================================== Problems 1, 2, and 6 are happening because __STDC__ isn't defined by default under MSVC. MS thinks that because they define various extensions they aren't strict ANSI C, so by default they define _MSC_EXTENSIONS instead. Here are the relevant bits from the docs: __STDC__ Indicates full conformance with the ANSI C standard. Defined as the integer constant 1 only if the /Za compiler option is given and you are not compiling C++ code; otherwise is undefined. _MSC_EXTENSIONS This macro is defined when compiling with the /Ze compiler option (the default). Its value, when defined, is 1. Because of all of the above, __P falls through to the #else at 1150 in gambit.h and treats params as K&R, which is wrong. The problem can be fixed by either looking specifically for something like _MFC_VER or _MSC_EXTENSIONS or by forcing a #define of __STDC__. (I took the second route in my project file.) Problem 11 looks legit. (The problem with ___REGISTER_HOST_ENTRY was described elsewhere.)

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Gambit-C 4.0 beta 13
by Marc Feeley 14 Mai '05

14 Mai '05

A new beta of Gambit-C 4.0 is now available in source form at this address: http://www.iro.umontreal.ca/~feeley/gambc40b13.tar.gz Here's what's new: - The "table" type. Tables map keys to values. Gambit has an efficient implementation of tables using hashing and open addressing. The runtime system and compiler now use tables internally instead of association lists in critical places. This improves the speed of the compiler when compiling large files containing many constants, or when the -debug option is used (on some tests the compiler runs 5 times faster). Tables can hold their keys weakly and/or their values weakly. The key comparison procedure and hashing procedure can be specified when a table is created. A reasonably efficient hashing procedure is used by default when the key comparison procedure is eq?, eqv?, equal?, string=? or string-ci=?. - Hashing. There are several hashing procedures (symbol-hash, keyword-hash, string=?-hash, string-ci=?-hash, eq?-hash, eqv?-hash, and equal?-hash). The procedures object->serial-number and serial-number->object are more efficient (thanks to eq? tables). - A new implementation of syntax-case is now included. This version preserves source-code location information, so it makes debugging easier than the previous version. It is usable in the interpreter and in the compiler. The integration with Gambit is not perfect: local variables are renamed, some special forms are transformed (e.g. when pretty-printing a procedure the code may look very different from what the programmer wrote), and some Gambit-specific special forms (such as ##namespace, ##declare, etc) are not available when using syntax-case. For this reason syntax-case is not enabled by default. To use it you must start Gambit like this: % gsi ~~/syntax-case - or load it from your customization file. - The web-server example has been extended to demonstrate how web-continuations can be used. There is also a fairly complete library for dynamically generating HTML. It shows how the ##namespace and ##include forms can be used to modularize code. - Most of the bugs and misfeatures reported on gambit-list have been fixed. Other bugs fixed: equal? on structures, passing Scheme functions to C, imprecise error messages, Mac OS X assembly code problem when using --enable-debug, and more. The system builds cleanly and has been tested in 32 bit and 64 bit environments (mainly Linux and Mac OS X). - The source code for GUIDE (Gambit Universal IDE) is now included in the distribution. Unfortunately, there were some problems getting the makefiles and configure script working properly with Qt, so currently GUIDE is disabled. I expect this to be fixed shortly. [If you feel adventurous the sources are in lib/guide.] - Gambit is now dual licensed. You have the option to choose between the Apache license and the LGPL. Marc

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Gambit b13 win32 build report
by Scott Graham 14 Mai '05

14 Mai '05

Hi Gambit, as of beta 13 isn't quite buildable on windows using msvc. I'm using the attached vs71 projects (which should be extracted to the root of the gambit directory to be used). btw, the proj_msc.zip project in 'misc' is out of date, and unlikely to be loadable by anyone anymore anyway. The errors I get are many like this: _thread.c c:\desktop\gambc40b13\lib\_thread.c(2479) : error C2065: '___REGISTER_HOST_ENTRY' : undeclared identifier c:\desktop\gambc40b13\lib\_thread.c(2479) : error C2146: syntax error : missing ';' before identifier '___jump' c:\desktop\gambc40b13\lib\_thread.c(2479) : error C2144: syntax error : '<Unknown>' should be preceded by '<Unknown>' c:\desktop\gambc40b13\lib\_thread.c(2479) : error C2144: syntax error : '<Unknown>' should be preceded by '<Unknown>' c:\desktop\gambc40b13\lib\_thread.c(2479) : error C2143: syntax error : missing ';' before 'identifier' ... Adding: #define ___REGISTER_HOST_ENTRY at line 3192 (in the #else of #ifdef ___USE_LABEL_VALUES) allows compilation to succeed. I do not have any substantial Gambit code to test with, but simple tests seemed to work ok. Also, I get the following moderately concerning warning, which looks to be becuase no device is set up when USE_POSIX isn't defined. I don't know of a good fix for this: c:\desktop\gambc40b13\lib\os_io.c(5527) : warning C4700: local variable 'dev' used without having been initialized thanks, scott

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Doc Bug?
by MichaelL＠frogware.com 13 Mai '05

13 Mai '05

Isn't the very first line of the manual incorrect? The Gambit programming system is a full implementation of the Scheme language which conforms to the R4RS and IEEE Scheme standards. Isn't Gambit now R5RS?

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Gambit.h error
by MichaelL＠frogware.com 13 Mai '05

13 Mai '05

On Windows, ___USE_LABEL_VALUES isn't defined. If you read through the code you can see an #ifdef at line 3115 and the #else at line 3167. Just after the "else" you can see that ___BEGIN_SW is #defined, and that it references ___REGISTER_HOST_ENTRY. The problem is that ___REGISTER_HOST_ENTRY isn't ever #defined along this code path. One solution--the one I used--is to add #define ___REGISTER_HOST_ENTRY at line 3176. The other (and probably better) option, I think, is to remove ___REGISTER_HOST_ENTRY from the __BEGIN_SW #define. I'm trying to compile Gambit under Visual Studio. Would you be interested in the solution (.sln) files since the existing project files are pretty old?

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srfi-13/14
by ben＠fuhok.net 12 Mai '05

12 Mai '05

I made a few changes to Brad's excellent char-set-lib and string-lib libraries. These versions can be used with gsi, and you don't have to compile them inside the gambit source tree. `gsc -dynamic' should do the trick. I also fixed a copy of small bugs --- hopefully I didn't introduce too many in their place ;-) I haven't tested these rigorously though. Gambit seems like an awfully nice Scheme, but as distributed it is too spartan for my needs. I'd like to help where I can with porting useful libraries. Regards, Ben

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Indicating unusual conditions
by Eric Merritt 08 Mai '05

08 Mai '05

I have a question concerning indicating unusual conditions in gambit. This is more a stylistic question rather then a technical question, but its worth knowing what others are doing. Say I have a piece of library code that accepts an optional timeout. There are any number of things that could occur if the timeout expires. For example, in SML/Ocaml I would probably just raise an exception. That's pretty standard in that language and it costs almost nothing in overhead. In Erlang I would probably return a tuple like {timeout, some_other_data}. What is usual way to do this in gambit? Is it common to simply raise an exception? Is it more acceptable to return a special value like Erlang or C? I am thinking that raising an exception is the correct thing to do, but I wouldn't mind having confirmation on that.

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Using the overflow tests from Hacker's Delight
by Bradley Lucier 08 Mai '05

08 Mai '05

Marc: Here are the diffs for _num.scm after I used the overflow tests from Hacker's Delight. There should be fewer jumps in ##+ and ##-, and fewer unnecessary calls to ##bignum.*. For example, with the old code we have 617203464 bytes allocated and 768376664 bytes allocated when using binary splitting applied to some series to compute e and pi to 10,000 digits, but with the new code we have 612389032 bytes allocated and 764550248 bytes allocated Not a big difference, but it may help more for other codes. Brad

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Straight dope on FIXADDP, FIXMULP, ...
by Bradley Lucier 07 Mai '05

07 Mai '05

Marc: There is a wonderful little book "Hacker's Delight" by Henry S. Warren Jr. (with a foreword by Guy Steele, BTW), that has a special section on "Overflow Detection" in Chapter 1, "Basics". The section begins on page 26. In this section you'll find all the tests for overflow of signed addition, subtraction, and multiplication that you need in ##+, ##-, and ##* and FIXADDP, FIXSUBP, and FIXMULP (which should all probably be merged (##+ with FIXADDP, etc., of course) in some way). Would you like me to look at some of the implementation details? Brad

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Gambit-list Mai 2005