hash = ( fpArray*2654404609 )>>12; // Calculate the hash and limit the value to 2^20 (1 Meg)

unsigned hash = fpArray * 2654404609;
hash = hash >> 12;

unsigned long hash = (unsigned long)fpArray * 2654404609;
hash = hash >> 12;
unsigned h2 = (unsigned)hash;

hash = ( fpArray*2654404609U )>>12; // Calculate the hash and limit the value to 2^20 (1 Meg)
(or)
const unsigned multipler = 2654404609; // here U suffix is not needed as the constant is explicitly made unsigned
hash = ( fpArray * multiplier ) >> 12;

    Now, the computation will happen with 32 bit numbers to get the expected outputs.

Lessons Learned here:

1. While using constants, beware of the upcasting and downcasting. So use proper suffixes like U, L, F etc.
2. Instead of using constants directly in expressions, use them as constant variables.
3. Be conscious about the compiler type and the assumptions made by the compiler in different build modes.

Building CXX object libs/bgt/CMakeFiles/bgt.dir/error.o
In file included from /opt/projects/stl/stlport/limits.h:27,
            from /usr/include/c++/4.4/../4.4.5/climits:43,
            from /opt/projects/stl/stlport/climits:27,
            from /opt/projects/stl/stlport/stl/_algobase.h:42,
            from /opt/projects/stl/stlport/stl/_alloc.h:47,
            from /opt/projects/stl/stlport/stl/_string.h:23,
            from /opt/projects/stl/stlport/stl/_ios_base.h:34,
            from /opt/projects/stl/stlport/stl/_ios.h:23,
            from /opt/projects/stl/stlport/stl/_ostream.h:24,
            from /opt/projects/stl/stlport/ostream:31,
            from /opt/projects/dev/libs/bgt/error.cpp:18:
/usr/include/../include/limits.h:125: error: no include path in which to search for limits.h
In file included from /opt/projects/stl/stlport/stl/_num_put.c:26,
            from /opt/projects/stl/stlport/stl/_num_put.h:183,
            from /opt/projects/stl/stlport/stl/_ostream.c:26,
            from /opt/projects/stl/stlport/stl/_ostream.h:380,
            from /opt/projects/stl/stlport/ostream:31,
            from /opt/projects/dev/libs/bgt/error.cpp:18:
/opt/projects/stl/stlport/stl/_limits.h:148: error: ‘CHAR_BIT’ was not declared in this scope
/opt/projects/stl/stlport/stl/_limits.h:253: error: ‘CHAR_MIN’ was not declared in this scope
..

Looks like it is a bug in the STLport package itself as per the Release notes of STLport.  After updating to STLport-5.2.1, the issue got fixed automatically.

So, I am left out with only one option; that is to create a C++ driver myself.  I found the C driver working excellently (although there are design glitches!).  I am currently developing a C++ wrapper around the C driver to support fundamental operations on Mongo from an application compiled with STLport in C++ and cross platform.

# view.php

# get the file id
$id = "";
if ( array_key_exists( "id", $_REQUEST ) ) {
    $id = $_REQUEST["id"];
}

# open database connectivity
$conn = new Mongo();
$store = $conn->store;
$image = $store->image;

# fetch the file as per the id or just randomly
if ( $id != "" ) {
    $query = array ( 'id' => $id );
    $cursor = $image->find( $query );
}
else {
    # set the html headers for refreshing the page every 3 sec.
    header( 'Refresh: 3;' );

    # Random fetch logic, get the count first.
    $count = $image->find()->count();
    $rand = rand( 1, $count-1 );  # generate a random number.
    # skip several records of the cursor based on the random number
    $cursor = $image->find()->skip( $rand )->limit(1);
}

# write output stream as JPEG content
header( 'Content-Type: image/jpeg' );
foreach ( $cursor as $obj ) {
    # decode the data, and just write on the output stream.
    echo base64_decode($obj["data"]);
}

# import.php

$dir = $_REQUEST["dir"];
if ( $dir == "" ) {
    echo "<h2>Import directory cannot be empty</h2>";
    exit;
}

$conn = new Mongo();
$db = $conn->store;
$image = $db->image;

echo "<ol>";
$dhandle = opendir( $dir );
while ( ($file = readdir( $dhandle )) != false ) {
    $path = $dir."/".$file;
    if ( is_dir( $path ) ) {
        continue;
    }

    $path = str_replace( '\\', '/', $path );
    $handle = fopen( $path, "rb" );
    $data = fread( $handle, filesize( $path ) );
    fclose( $handle );
    if ( $data == false ) {
	continue;
    }

    $key = preg_replace( "/[[:punct:]]/", "_", $file );
    echo "<li>Importing $path (Key: $key)...";
    try {
        $image->insert( array( "id" => $key,
               "data" => base64_encode( $data ) ), true );
        echo "Success";
    }
    catch ( MongoCursorException $e ) {
        echo "Exception: $e";
    }

    echo "</li>";
    ob_flush();
}

echo "</ol>";

Within minutes, I was able to have a browser based slide show application, which protected all my image files in the Database without being exposed out in the folder system.

I am enjoying every bit of Mongo, and hope to develop several application using that in the future.

# if defined (_MSC_VER) && (_MSC_FULL_VER >= 140050000)
// Checked iterators are currently only supported in MSVC++ 8 or better.
#  include <iterator>
# endif  /* _MSC_VER >= 1400 */

# if defined (_MSC_VER) && (_MSC_FULL_VER >= 140050000)
template <typename PTR>
stdext::checked_array_iterator<PTR>
ACE_make_checked_array_iterator (PTR buf, size_t len)
{
return stdext::checked_array_iterator (buf, len);
}
# else
template <typename PTR>
PTR
ACE_make_checked_array_iterator (PTR buf, size_t /* len */)
{
// Checked iterators are unsupported.  Just return the pointer to
// the buffer itself.
return buf;
}
# endif  /* _MSC_VER >= 1400 */

#endif  /* ACE_CHECKED_ITERATOR_H */

I need to develop a solution to it.  The easiest way to find a solution is to use some macro explicitly set by the STLport header, which is not set by any other STL libraries.  I chose to use the _STLP_ITERATOR macro set by “stl/stlport/iterator” header.

#ifndef _STLP_ITERATOR
#define _STLP_ITERATOR

# ifndef _STLP_OUTERMOST_HEADER_ID
#  define _STLP_OUTERMOST_HEADER_ID 0×38
#  include <stl/_prolog.h>
# endif

# ifdef _STLP_PRAGMA_ONCE
#  pragma once
# endif

#if defined (_STLP_IMPORT_VENDOR_STD)
# include _STLP_NATIVE_HEADER(iterator)
#endif /* IMPORT */

# ifndef _STLP_INTERNAL_ITERATOR_H
#  include <stl/_iterator.h>
# endif

# ifndef _STLP_INTERNAL_STREAM_ITERATOR_H
#  include <stl/_stream_iterator.h>
# endif

# if (_STLP_OUTERMOST_HEADER_ID == 0×38)
#  include <stl/_epilog.h>
#  undef _STLP_OUTERMOST_HEADER_ID
# endif

#endif /* _STLP_ITERATOR */

The solution is the following, where I have added the !defined(_STLP_ITERATOR) condition along with the check for Visual Studio compiler version.

# if !defined(_STLP_ITERATOR) && defined (_MSC_VER) && (_MSC_FULL_VER >= 140050000)
// Checked iterators are currently only supported in MSVC++ 8 or better.
#  include <iterator>
# endif  /* _MSC_VER >= 1400 */

# if defined (_MSC_VER) && (_MSC_FULL_VER >= 140050000)
template <typename PTR>
stdext::checked_array_iterator <PTR>
ACE_make_checked_array_iterator (PTR buf, size_t len)
{
return stdext::checked_array_iterator (buf, len);
}
# else
template <typename PTR>
PTR
ACE_make_checked_array_iterator (PTR buf, size_t /* len */)
{
// Checked iterators are unsupported. Just return the pointer to
// the buffer itself.
return buf;
}
#
endif  /* _MSC_VER >= 1400 */

#endif
/* ACE_CHECKED_ITERATOR_H */

1. Install glibc.i386, glibc-devel.i386
2. Install libgcc.i386
3. Install libstdc++.i386

#include <cstdio>
#include <iostream>
main()
{
    std::cout << “C++” << std::endl;
    printf ( “long: %d\n”, sizeof(long) );
    printf ( “long long: %d\n”, sizeof(long long) );
    return 0;
}

To compile in native 64bit:
[sudar@tstsrv12 tmp]$ g++ -m64 -o out64 code.cpp

[sudar@tstsrv12 tmp]$ ./out64
C++
long: 8
long long: 8

[sudar@tstsrv12 tmp]$ ldd out64
        linux-vdso.so.1 =>  (0x00007fffc43fe000)
        libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x0000003e7be00000)
        libm.so.6 => /lib64/libm.so.6 (0×0000000000601000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x0000003e79e00000)
        libc.so.6 => /lib64/libc.so.6 (0×0000000000886000)
        /lib64/ld-linux-x86-64.so.2 (0×0000000000110000)

To compile in 32bit:
[sudar@tstsrv12 tmp]$ g++ -m32 -o out32 code.cpp

[sudar@tstsrv12 tmp]$ ./out32
C++
long: 4
long long: 8

[sudar@tstsrv12 tmp]$ ldd out32
        linux-gate.so.1 =>  (0×00130000)
        libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0×00133000)
        libm.so.6 => /lib/libm.so.6 (0×00223000)
        libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x0024c000)
        libc.so.6 => /lib/libc.so.6 (0x0025a000)
        /lib/ld-linux.so.2 (0×00110000)

#include <rpc.h>      // for UUID, UuidCreateSequential
#include <cstring>    // for memcpy
#include <algorithm>  // for std::swap

unsigned __int64
MACAddress( void ) const
{
    UUID u;
    ::UuidCreateSequential( &u );

    u.Data4[0] = u.Data4[1] = 0;

    std::swap( u.Data4[0], u.Data4[7] );
    std::swap( u.Data4[1], u.Data4[6] );
    std::swap( u.Data4[2], u.Data4[5] );
    std::swap( u.Data4[3], u.Data4[4] );

    unsigned __int64 code;
    ::memcpy( &code, &u.Data4, sizeof(u.Data4) );

    return code;
}   // MACAddress

Let me share another hack. If you want to generate strings which do not repeat themselves, you could use UuidCreate() Win32 API, which generates unique UUIDs everytime the function is called.  The UUID thus obtained can be converted to a number or a string depending upon the need, which guarantees non-repeatable ids.

Error: Can not start thread: error writing TLS. (error 87: the parameter is incorrect.)

I was not able to reason out this behavior. I tried changing between THREAD_DETACHABLE and THREAD_JOINABLE, but was not able to get through.  When I search for hints from the web, I got the following link.

http://osdir.com/ml/lib.wxwindows.general/2004-01/msg00759.html

It was advised to create a dummy wxInitializer object so that the wxWidgets platform does the necessary initialization.  wxInitializer class is an undocumented class and called internally when a wxFrame or wxDialog based GUI application is built.  Typically, wxInitializer object is instantiated internally by the wxApp class.  Since, in my application there is no wxApp object which led to the above problem

When I dug the declaration of wxInitializer class, I found it declared at wx/init.h;  Also I found that instead of instantiating the object, we may call the following function.

extern bool WXDLLIMPEXP_BASE wxInitialize(int argc = 0, wxChar **argv = NULL);

In my application, I did the following:

main( int argc, char **argv )
{
      extern bool wxInitialize( int, char ** );
      wxInitialize( argc, argv );
      ….
      ….
}

It worked like piece of cream.

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I was looking for a framework to run FFT operation on a Windows Mobile 6 platform in native C++. Unfortunately, there are none. So, I decided to port the framework myself and indeed I was successful too. I have placed the framework at www.sudarsun.in/downloads/FFTW-3.0.1-ARMV4I.zip. It does not contain any documentation. I shall update it ASAP.

SVDui.exe – 33 error(s), 0 warning(s)

The solution to the above problem is to add “rpcrt.lib comctl32.lib” at project settings->Link->object/library modules
along with “kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib
advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib
odbccp32.lib”.