/home66/gary/public_html/cloudy/c08_branch/source/cpu.cpp

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/* This file is part of Cloudy and is copyright (C)1978-2008 by Gary J. Ferland and
 * others.  For conditions of distribution and use see copyright notice in license.txt */
#if defined(__HP_aCC)
/* this is for the HP compiler on the sdx */
extern "C" unsigned long fegettrapenable();
extern "C" void fesettrapenable(unsigned long); 
#endif

#if defined(__ia64) && defined(__INTEL_COMPILER)
extern "C" unsigned long fpgetmask();
extern "C" void fpsetmask(unsigned long);
#endif  

#if defined(__sun) || defined(__sgi)
#include <ieeefp.h>
#if defined(HAVE_SUNMATH) || defined(FLUSH_DENORM_TO_ZERO)
#include <sunmath.h>
#endif
#endif

#if defined(__alpha) && defined(__linux) && defined(__GNUC__)
#define __USE_GNU
#include <fenv.h>
#endif

#ifdef __unix
#include <unistd.h>
#endif

/* the redefinition of float in cddefines.h can cause problems in system headers
 * hence these includes MUST come after the system header includes above */
#include "cddefines.h"
#include "path.h"
#include "trace.h"

/* NB NB - this constructor needs to be called before any of the user code is executed !! */
t_cpu::t_cpu()
{
        DEBUG_ENTRY( "t_cpu()" );

#ifdef CATCH_SIGNAL
        // set up signal handlers so that we can properly terminate MPI runs...

#       ifdef __unix
        p_action.sa_handler = &signal_handler;
        sigemptyset( &p_action.sa_mask );
        p_action.sa_flags = SA_NODEFER;

        p_default.sa_handler = SIG_DFL;
        sigemptyset( &p_default.sa_mask );
        p_default.sa_flags = SA_NODEFER;

        for( int sig=1; sig <= 31; sig++ )
        {
                // is the signal valid?
                if( sigaction( sig, NULL, NULL ) == 0 )
                        // these two are for suspending and resuming a job
                        if( sig != SIGSTOP && sig != SIGCONT )
                                sigaction( sig, action(), NULL );
        }
#       endif

#       ifdef _MSC_VER
        signal( SIGABRT, &signal_handler );
        signal( SIGFPE, &signal_handler );
        signal( SIGILL, &signal_handler );
        signal( SIGINT, &signal_handler );
        signal( SIGSEGV, &signal_handler );
        signal( SIGTERM, &signal_handler );
#       endif
#endif

        /* >>chng 05 dec 14, add test of endianness of the CPU, PvH */
        endian.c[0] = 0x12;
        endian.c[1] = 0x34;
        endian.c[2] = 0x56;
        endian.c[3] = 0x78;

        /* >>chng 05 dec 15, add signaling NaN for float and double to cpu struct, PvH */
        /* in C++ this should be replaced by numeric_limits<TYPE>::signaling_NaN() */
        if( sizeof(sys_float) == 4 )
        {
#               ifdef __mips
                /* definition of signaling and quiet NaN is reversed on MIPS */
                Float_SNaN_Value = 0xffffffff;
#               else
                if( big_endian() || little_endian() )
                {
                        /* this should work on most modern CPU's */
                        Float_SNaN_Value = 0xffbfffff;
                }
                else
                {
                        /* this is an unusual CPU -> bit pattern for SNaN is unknown */
                        Float_SNaN_Value = -1;
                }
#               endif
        }
        else
        {
                /* this is an unusual CPU -> bit pattern for SNaN is unknown */
                Float_SNaN_Value = -1;
        }

#       ifdef HAVE_INT64

        if( sizeof(double) == 8 )
        {
#               ifdef __mips
                /* definition of signaling and quiet NaN is reversed on MIPS */
                Double_SNaN_Value = 0xffffffffffffffff;
#               else
                /* this should work on most modern CPU's */
                Double_SNaN_Value = 0xfff7ffffffbfffff;
#               endif
        }
        else
        {
                /* this is an unusual CPU -> bit pattern for SNaN is unknown */
                Double_SNaN_Value = -1;
        }

#       else

        if( sizeof(double) == 8 )
        {
#               ifdef __mips
                /* definition of signaling and quiet NaN is reversed on MIPS */
                Double_SNaN_Value[0] = 0xffffffff;
                Double_SNaN_Value[1] = 0xffffffff;
#               else
                if( big_endian() )
                {
                        /* this should work on most modern CPU's */
                        Double_SNaN_Value[0] = 0xfff7ffff;
                        Double_SNaN_Value[1] = 0xffbfffff;
                }
                else if( little_endian() )
                {
                        /* this should work on most modern CPU's */
                        Double_SNaN_Value[0] = 0xffbfffff;
                        Double_SNaN_Value[1] = 0xfff7ffff;
                }
                else
                {
                        /* this is an unusual CPU -> bit pattern for SNaN is unknown */
                        Double_SNaN_Value[0] = -1;
                        Double_SNaN_Value[1] = -1;
                }
#               endif
        }
        else
        {
                /* this is an unusual CPU -> bit pattern for SNaN is unknown */
                Double_SNaN_Value[0] = -1;
                Double_SNaN_Value[1] = -1;
        }

#       endif

        /* set FP environment to trap FP exceptions */
        enable_traps();

        /* default is for failed asserts not to abort */
        p_lgAssertAbort = false;

        const char *str;

        /* determine the no. of CPUs on this machine; used by PHYMIR, grid command, .... */
#       if defined(_SC_NPROCESSORS_ONLN)  /* Linux, Sun Sparc, DEC Alpha */
        n_avail_CPU = sysconf(_SC_NPROCESSORS_ONLN);
#       elif defined(_SC_NPROC_ONLN)      /* SGI Iris */
        n_avail_CPU = sysconf(_SC_NPROC_ONLN);
#       elif defined(_SC_CRAY_NCPU)       /* Cray */
        n_avail_CPU = sysconf(_SC_CRAY_NCPU);
#       elif defined(_WIN32)
        str = getenv( "NUMBER_OF_PROCESSORS" );
        if( str != NULL )
        {
                int found = sscanf( str, "%ld", &n_avail_CPU );
                if( found != 1 )
                        n_avail_CPU = 1;
        }
        else
        {
                n_avail_CPU = 1;
        }
#       else                              
        /* Other systems, supply no. of CPUs on OPTIMIZE PHYMIR command line */
        n_avail_CPU = 1;
#       endif

#       ifdef _WIN32    
        str = getenv( "COMPUTERNAME" );
#       else
        str = getenv( "HOSTNAME" );
#       endif

        if( str != NULL )
                strncpy( HostName, str, STDLEN );
        else
                strncpy( HostName, "unknown", STDLEN );
        HostName[STDLEN-1] = '\0';

        /* pick up the path from the environment, if set by user */
        const char *path = getenv( "CLOUDY_DATA_PATH" );

        /* if the environment variable was not set, the default set in path.h takes effect */
        string chSearchPathRaw = ( path != NULL ) ? string( path ) : string( CLOUDY_DATA_PATH );

#       ifdef _WIN32
        string separator( ";" );
        char chExpectedEnd = '\\';
#       else
        string separator( ":" );
        char chExpectedEnd = '/';
#       endif

        chSearchPath.push_back( "" ); // the current working directory should be first and last
        Split( chSearchPathRaw, separator, chSearchPath, SPM_RELAX );
        chSearchPath.push_back( "" );

        for( vector<string>::size_type i=0; i < chSearchPath.size(); ++i )
        {
                if( chSearchPath[i].length() > 0 )
                {
                        /* get last valid char */
                        char chEnd = *chSearchPath[i].rbegin();

                        /* make sure path ends with directory separator */
                        if( chEnd != chExpectedEnd )
                                chSearchPath[i] += chExpectedEnd;
                }
        }

        nFileDone = 0;
}

void t_cpu::enable_traps() const
{
        /* >>chng 01 aug 07, added code to circumvent math library bug with g++ on
         * alpha-linux machines, see bug report 51072 on http://bugzilla.redhat.com, PvH */
        /* >>chng 01 apr 17, added code for Solaris and SGI operating systems, PvH */
        /* this routine contains no code for alphas or crays, they do not need
         * special code to enable FP exceptions since they are enabled by default */

        /* there is no command line option on MS Visual Studio to force crash */
#       if defined(_MSC_VER)
        volatile unsigned int NewMask;

        /* | is a bitwise inclusive or, turns on bits
         * 0|0 = 0
         * 0|1 = 1|0 = 1|1 = 1 */
        NewMask = _EM_ZERODIVIDE | _EM_OVERFLOW | _EM_INVALID;
        /* ~ is the unary bitwise complement - all bits flip */ 
        NewMask = ~NewMask;
        _controlfp( NewMask , _MCW_EM );

        /* this is the code for Linux PC (but not Linux alpha) to force crash */
        /* >>chng 04 apr 26, added support for AMD64, enable FPE traps for SSE/SSE2, PvH */
        /* >>chng 06 aug 12, added support for Apple MacOSX, and hopefully also Solaris x86, PvH */
#       elif defined(__GNUC__) && ( defined(__i386) || defined(__amd64) )
        volatile unsigned int Old_Mask, New_Mask;
#       if defined(__SSE__) || defined(__SSE2__)
        volatile unsigned int SSE_Mask;
#       endif

#       define _FPU_MASK_IM  0x01  /* Invalid          */
#       define _FPU_MASK_DM  0x02  /* Denormalized     */
#       define _FPU_MASK_ZM  0x04  /* Division-by-zero */
#       define _FPU_MASK_OM  0x08  /* Overflow         */
#       define _FPU_MASK_UM  0x10  /* Underflow        */
#       define _FPU_MASK_PM  0x20  /* Inexact          */

        /*  | is a bitwise inclusive or, turns on bits     */
        /* 0|0 = 0                                         */
        /* 0|1 = 1|0 = 1|1 = 1                             */

        /*  ~ is the unary bitwise complement - all bits flip */

        /* this enables FPE traps for regular i387 FP instructions */

        volatile unsigned int UnMask = ~((unsigned int)( _FPU_MASK_ZM | _FPU_MASK_IM  | _FPU_MASK_OM ));

        __asm__ volatile("fnstcw %0" : "=m" (*&Old_Mask));

        New_Mask = Old_Mask & UnMask;

        __asm__ volatile("fldcw %0" : : "m" (*&New_Mask));

#       if defined(__SSE__) || defined(__SSE2__)

#       if defined(FLUSH_DENORM_TO_ZERO)
        /* using this causes denormalized numbers to be flushed to zero,
         * which will speed up the code on Pentium 4 processors */
        SSE_Mask = 0x9900;
#       else
        /* this version allows denormalized numbers to be retained */
        SSE_Mask = 0x1900;
#       endif

        /* this enables FPE traps for SSE/SSE2 instructions */

        __asm__ volatile( "ldmxcsr %0" : : "m" (*&SSE_Mask) );

#       endif

        /* this is for IA64 systems running g++ or icc (e.g. SGI, HP, ...) */
#       elif defined(__ia64)

#       define FPSR_TRAP_VD     (1 << 0)        /* invalid op trap disabled */
#       define FPSR_TRAP_DD     (1 << 1)        /* denormal trap disabled */
#       define FPSR_TRAP_ZD     (1 << 2)        /* zero-divide trap disabled */
#       define FPSR_TRAP_OD     (1 << 3)        /* overflow trap disabled */
#       define FPSR_TRAP_UD     (1 << 4)        /* underflow trap disabled */
#       define FPSR_TRAP_ID     (1 << 5)        /* inexact trap disabled */

#       define FPSR_SF0_FTZ     (1 << 6)        /* flush denormalized numbers to zero */

#       if defined(__GNUC_EXCL__)
        /* __asm__ instructions are not supported by icc as of v9.0 */
#       define _IA64_REG_AR_FPSR    40

#       define ia64_getreg( regnum )       __asm__ volatile( "mov %0=ar%1" : "=r" (fpsr) : "i"(regnum) )
#       define ia64_setreg( regnum, val )  __asm__ volatile( "mov ar%0=%1" :: "i" (regnum), "r"(val): "memory" )
#       define ia64_serialize              __asm__ volatile( "srlz.i" );

        volatile unsigned long fpsr, flags = FPSR_TRAP_VD | FPSR_TRAP_ZD | FPSR_TRAP_OD;

        ia64_getreg( _IA64_REG_AR_FPSR );
        fpsr &= ~flags;
#       if defined(FLUSH_DENORM_TO_ZERO)
        fpsr |= FPSR_SF0_FTZ;
#       endif
        ia64_setreg( _IA64_REG_AR_FPSR, fpsr );
        /* this prevents RAW and WAW dependency violations in case this ever gets inlined... */
        ia64_serialize;

#       elif defined(__INTEL_COMPILER)
        /* this is for icc on IA64 SGI machines */
        unsigned long fpsr = fpgetmask();
        fpsr |= FPSR_TRAP_VD | FPSR_TRAP_ZD | FPSR_TRAP_OD;
        fpsetmask( fpsr );
#       elif defined(__HP_aCC)
        /* this is for the HP compiler on the sdx */
        unsigned long fpsr = fegettrapenable(); 
        fpsr |= FPSR_TRAP_VD | FPSR_TRAP_ZD | FPSR_TRAP_OD;
        fesettrapenable( fpsr ); 
#       endif /* defined(__GNUC_EXCL__) */

        /* this is for Solaris and SGI to force crash */
#       elif defined(__sun) || defined(__sgi)

        fp_except mask;

        /* >>chng 05 dec 30, accept FLUSH_DENORM_TO_ZERO as a synonym for HAVE_SUNMATH, PvH */
#       if defined(HAVE_SUNMATH) || defined(FLUSH_DENORM_TO_ZERO)

        /* >>chng 01 oct 09, disable gradual underflow on ultrasparc whith g++
         * (only needed for versions < 3.1 or >= 4.3.0, see Note 1).
         *
         * compile this module with:
         *     g++ [ other options... ] -I<include-dir> -DHAVE_SUNMATH -c cpu.cpp
         * link the program with:
         *     g++ -L<library-dir> -o cloudy.exe *.o -lsunmath
         *
         * you probably need to use -I<include-dir> and -L<library-dir> to point the
         * compiler/linker to the location of the sunmath.h header file and libsunmath.so
         * library (e.g., -I/opt/SUNWspro/prod/include/cc -L/opt/SUNWspro/lib; note that
         * the actual location may vary from one installation to another).
         * See also bug report 4487 on http://gcc.gnu.org/bugzilla/
         *
         * Note 1: Starting with g++ 3.1, bug 4487 has been solved: -funsafe-math-optimizations
         * will automatically disable gradual underflow. Hence using nonstandard_arithmetic()
         * is no longer necessary. The option -funsafe-math-optimizations should be included
         * both when compiling and linking:
         *
         * g++ [ other options... ] -funsafe-math-optimizations -c *.c
         * g++ [ other options... ] -funsafe-math-optimizations -o cloudy.exe *.o
         *
         * Starting with g++ 4.3.0 the -funsafe-math-optimizations option can no longer be
         * used as it implicitly enables -fno-trapping-math, which is unsafe for Cloudy
         * because we do trap floating point exceptions.
         *
         * Note 2: Don't use nonstandard_arithmetic() with CC (the SunWorks/Forte compiler);
         * use the -fast commandline option instead to disable gradual underflow (or use
         * -fnonstd if you don't want all the other options enabled by -fast). The option
         * -fast (or -fnonstd) should be included both when compiling and linking:
         *
         * CC [ other options... ] -fast -c *.c
         * CC -fast -o cloudy.exe *.o
         *
         * PvH */
        nonstandard_arithmetic();
#       endif

        /* enable floating point exceptions on sun and sgi */
        mask = fpgetmask();
        mask = mask | FP_X_INV | FP_X_OFL | FP_X_DZ;
        fpsetmask(mask);

#       elif defined(__alpha) && defined(__linux) && defined(__GNUC__)

        /* the following is not supported on all hardware platforms, but certainly for EV56
         * and later. earlier versions may work as well, but that has not been tested.
         * for details see https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=51072 */
#       ifdef FE_NONIEEE_ENV
        /* this prevents the infamous math library bug when compiling with gcc on alpha-linux
         * machines. if this doesn't work on your system, the only alternative is to link
         * against the Compaq math library: gcc *.o -lcpml -lm, or use ccc itself, PvH */
        fesetenv(FE_NONIEEE_ENV);
#       endif

#       endif
        return;
}

void t_cpu::signal_handler(int sig)
{
        // when an FPE is caught, the mask is reset...
        cpu.enable_traps();
#       ifdef _MSC_VER
        // at this point the signal handler has reverted to the default handler
        signal( sig, &signal_handler );
#       endif
        throw bad_signal( sig );
}


void t_cpu::printDataPath() const
{
        fprintf(ioQQQ, "The path is:\n");
        for( vector<string>::size_type i=1; i < cpu.chSearchPath.size()-1; ++i )
                fprintf( ioQQQ, "   ==%s==\n", cpu.chSearchPath[i].c_str() );
}

FILE* open_data( const char* fname, const char* mode, access_scheme scheme )
{
        DEBUG_ENTRY( "open_data()" );

        FILE* handle = NULL;
        string FileName( fname );
        vector<string>::size_type begin, end;
        bool lgAbort = ( scheme == AS_DATA_ONLY || scheme == AS_DATA_OPTIONAL || scheme == AS_DATA_LOCAL ||
                         scheme == AS_LOCAL_DATA || scheme == AS_LOCAL_ONLY );

        switch( scheme )
        {
        case AS_DATA_ONLY:
        case AS_DATA_ONLY_TRY:
        case AS_DATA_OPTIONAL:
                begin = 1;
                end = cpu.chSearchPath.size()-1;
                break;
        case AS_DATA_LOCAL:
        case AS_DATA_LOCAL_TRY:
                begin = 1;
                end = cpu.chSearchPath.size();
                break;
        case AS_LOCAL_DATA:
        case AS_LOCAL_DATA_TRY:
                begin = 0;
                end = cpu.chSearchPath.size()-1;
                break;
        case AS_LOCAL_ONLY:
        case AS_LOCAL_ONLY_TRY:
                begin = 0;
                end = 1;
                break;
        default:
                TotalInsanity();
        }

        string FullName;
        for( vector<string>::size_type i=begin; i < end && handle == NULL; ++i )
        {
                FullName = cpu.chSearchPath[i] + FileName;
                handle = fopen( FullName.c_str(), mode );
        }

        if( trace.lgTrace )
                fprintf( ioQQQ, " opening %s mode %s handle %p\n", FullName.c_str(), mode, handle );

        if( handle == NULL && lgAbort )
        {
                if( scheme == AS_DATA_OPTIONAL )
                        // presence is optional -> make warning less scary...
                        fprintf( ioQQQ, "\nI could not open the data file %s\n\n", fname );
                else
                        fprintf( ioQQQ, "\nPROBLEM DISASTER I could not open the data file %s\n\n", fname );
                if( cpu.nFileDone == 0 || scheme == AS_DATA_ONLY )
                {
                        // failed on very first open -> most likely path is not correct
                        // failed on AS_DATA_ONLY -> CLOUDY_DATA_PATH may point to obsolete data dir
                        fprintf( ioQQQ, "Although there may be other reasons you have received this error,\n");
                        fprintf( ioQQQ, "the most likely are that the path has not been properly set\n");
                        fprintf( ioQQQ, "or that the path points to an old version of the data.\n\n");
                        fprintf( ioQQQ, "Please have a look at the file path.h in the source directory\n");
                        fprintf( ioQQQ, "to check how the variable CLOUDY_DATA_PATH is set - \n");
                        fprintf( ioQQQ, "it should give the location of the data files I need.\n");
                        fprintf( ioQQQ, "These are the files in the data download from the web site.\n\n");
                        fprintf( ioQQQ, "Recompile the code with the correct data path set in path.h\n");
                        fprintf( ioQQQ, "or use the shell command \"export CLOUDY_DATA_PATH=path\" to set the\n");
                        fprintf( ioQQQ, "path from a bash command prompt.\n\n");
                        cpu.printDataPath();
                }
                else
                {
                        // failed on search including local directory -> most likely the file name
                        // was mistyped on a compile command, or Cloudy is run in the wrong directory
                        // if scheme == AS_DATA_OPTIONAL, this most likely is a stellar grid that is not installed.
                        fprintf( ioQQQ, "These are all the paths I tried:\n" );
                        for( vector<string>::size_type i=begin; i < end; ++i )
                        {
                                if( cpu.chSearchPath[i].length() > 0 )
                                        fprintf( ioQQQ, "   ==%s==\n", cpu.chSearchPath[i].c_str() );
                                else
                                        fprintf( ioQQQ, "   ==<local directory>==\n" );
                        }
                        // AS_DATA_OPTIONAL files should provide their own message (currently only stellar grids)
                        if( scheme != AS_DATA_OPTIONAL )
                        {
                                fprintf( ioQQQ, "\nAlthough there may be other reasons you have received this error,\n");
                                fprintf( ioQQQ, "the most likely are that you mistyped the file name, or that you\n");
                                fprintf( ioQQQ, "are running Cloudy in the wrong directory. If you are running a\n");
                                fprintf( ioQQQ, "COMPILE command, this needs to be done in the data directory.\n\n");
                                fprintf( ioQQQ, "Otherwise, please have a look at the file path.h in the source\n");
                                fprintf( ioQQQ, "directory to check how the variable CLOUDY_DATA_PATH is set - \n");
                                fprintf( ioQQQ, "it should give the location of the data files I need.\n");
                                fprintf( ioQQQ, "These are the files in the data download from the web site.\n\n");
                                fprintf( ioQQQ, "Recompile the code with the correct data path set in path.h\n");
                                fprintf( ioQQQ, "or use the shell command \"export CLOUDY_DATA_PATH=path\" to set the\n");
                                fprintf( ioQQQ, "path from a bash command prompt.\n\n");
                        }
                }
                fprintf(ioQQQ, "Sorry.\n\n\n");
                cdEXIT(EXIT_FAILURE);
        }

        ++cpu.nFileDone;

        return handle;
}

void set_NaN(sys_float &x)
{
        if( sizeof(sys_float) == 4 )
                *reinterpret_cast<int32*>(&x) = cpu.Float_SNaN_Value;
        else
                x = -FLT_MAX;
}

void set_NaN(sys_float x[], /* x[n] */
             long n)
{
        long i;

        if( sizeof(sys_float) == 4 )
        {
                int32 *y = reinterpret_cast<int32*>(x);
                for( i=0; i < n; i++ )
                        *y++ = cpu.Float_SNaN_Value;
        }
        else
        {
                for( i=0; i < n; i++ )
                        x[i] = -FLT_MAX;
        }
}

void set_NaN(double &x)
{
        if( sizeof(double) == 8 )
        {
#               ifdef HAVE_INT64
                *reinterpret_cast<int64*>(&x) = cpu.Double_SNaN_Value;
#               else
                int32 *y = reinterpret_cast<int32*>(&x);
                *y++ = cpu.Double_SNaN_Value[0];
                *y = cpu.Double_SNaN_Value[1];
#               endif
        }
        else
                x = -DBL_MAX;
}

/* set_NaN - set NaN */
void set_NaN(double x[], /* x[n] */
             long n)
{
        long i;

        if( sizeof(double) == 8 )
        {
#               ifdef HAVE_INT64
                int64 *y = reinterpret_cast<int64*>(x);
                for( i=0; i < n; i++ )
                        *y++ = cpu.Double_SNaN_Value;
#               else
                int32 *y = reinterpret_cast<int32*>(x);
                for( i=0; i < n; i++ )
                {
                        *y++ = cpu.Double_SNaN_Value[0];
                        *y++ = cpu.Double_SNaN_Value[1];
                }
#               endif
        }
        else
        {
                for( i=0; i < n; i++ )
                        x[i] = -DBL_MAX;
        }
}

bool MyIsnan(sys_float &x)
{
        if( sizeof(sys_float) == 4 && FLT_MAX_EXP-FLT_MIN_EXP+3 == 256 )
        {
                int32 *p = reinterpret_cast<int32*>(&x);
                int32 r = *p & 0x7f800000; r ^= 0x7f800000;
                int32 s = *p & 0x007fffff;
                return ( r == 0 && s != 0 );
        }
        else
                /* we don't understand this CPU */
                return false;
}

bool MyIsnan(double &x)
{
        if( sizeof(double) == 8 && DBL_MAX_EXP-DBL_MIN_EXP+3 == 2048 )
        {
#               ifdef HAVE_INT64
                int64 *p = reinterpret_cast<int64*>(&x);
                int64 r = *p & 0x7ff0000000000000; r ^= 0x7ff0000000000000;
                int64 s = *p & 0x000fffffffffffff;
                return ( r == 0 && s != 0 );
#               else
                int32 *p = reinterpret_cast<int32*>(&x);
                if( cpu.little_endian() )
                {
                        int32 r = p[1] & 0x7ff00000; r ^= 0x7ff00000;
                        int32 s = p[1] & 0x000fffff; s |= p[0];
                        return ( r == 0 && s != 0 );
                }
                else if( cpu.big_endian() )
                {
                        int32 r = p[0] & 0x7ff00000; r ^= 0x7ff00000;
                        int32 s = p[0] & 0x000fffff; s |= p[1];
                        return ( r == 0 && s != 0 );
                }
                else
                        /* we don't understand this CPU */
                        return false;
#               endif
        }
        else
                /* we don't understand this CPU */
                return false;
}

---