endian test using C

Code can be used to test a machine, and also includes big-endian/little-endian converters (for float and double), which can be modified and included into C++.

Just copy the code into a file, for example “endiantest.c,” then compile it using “gcc endiantest.c,” and execute “a.out.”

Good luck!

Hao

#include <stdio.h>

float floatSWAP(float f)
{
union
{
float f;
unsigned char b[4];
} dat1, dat2;

dat1.f = f;
dat2.b[0] = dat1.b[3];
dat2.b[1] = dat1.b[2];
dat2.b[2] = dat1.b[1];
dat2.b[3] = dat1.b[0];
return dat2.f;
}

double doubleSWAP(double df)
{
union
{
double df;
unsigned char b[8];
} dat1, dat2;

dat1.df = df;
dat2.b[0] = dat1.b[7];
dat2.b[1] = dat1.b[6];
dat2.b[2] = dat1.b[5];
dat2.b[3] = dat1.b[4];
dat2.b[4] = dat1.b[3];
dat2.b[5] = dat1.b[2];
dat2.b[6] = dat1.b[1];
dat2.b[7] = dat1.b[0];
return dat2.df;
}

int IsBigEndian()
{
short int word = 0x0001;
char *byte = (char *) &word;
return (byte[0] ? 0:1);
}

float BEfloat(float f)
{
if (IsBigEndian())
return f;
else
return floatSWAP(f);
}

float LEfloat(float f)
{
if (IsBigEndian())
return floatSWAP(f);
else
return f;
}

double BEdouble(double df)
{
if (IsBigEndian())
return df;
else
return doubleSWAP(df);
}

double LEdouble(double df)
{
if (IsBigEndian())
return doubleSWAP(df);
else
return df;
}

int main(void)
{
float f, sf;
double df, sdf;
unsigned char * ch;

f = 32.45;
sf = floatSWAP(f);
printf("%f:%f\n%f\n",f,sf,BEfloat(f));
ch = (unsigned char *) &f;
printf("%1x%1x%1x%1x:",*ch,*(ch+1),*(ch+2),*(ch+3));
ch = (unsigned char *) &sf;
printf("%1x%1x%1x%1x\n\n",*ch,*(ch+1),*(ch+2),*(ch+3));

df = 10.23456789;
sdf = doubleSWAP(df);
printf("%13.10g:%13.10g\n%13.10g\n",df,sdf,BEdouble(df));
ch = (unsigned char *) &df;
printf("%1x%1x%1x%1x%1x%1x%1x%1x:",*ch,*(ch+1),*(ch+2),*(ch+3),*(ch+4),*(ch+5),*(ch+6),*(ch+7));
ch = (unsigned char *) &sdf;
printf("%1x%1x%1x%1x%1x%1x%1x%1x\n\n",*ch,*(ch+1),*(ch+2),*(ch+3),*(ch+4),*(ch+5),*(ch+6),*(ch+7));

if (IsBigEndian())
printf("This is Big-Endian machine.\n");
else
printf("This is Little-Endian machine.\n");
}

latex multi-plots using minipage

\begin{figure}[h!]
\begin{minipage}{0.5\textwidth}
\begin{tabular}{c}
\includegraphics[width=\textwidth]{SPU64.eps} \\
(a)
\end{tabular}
\end{minipage}
%\hfill
\begin{minipage}{0.5\textwidth}
\begin{tabular}{c}
\includegraphics[width=\textwidth]{SPW64.eps} \\
(b)
\end{tabular}
\end{minipage}
\caption{Normalized streamwise velocity spectra (a) and vertical velocity spectra (b) at different heights obtained from $64^3$ LES. Numbers in plots denote normalized heights ($z/H$).}
\label{fig:SP64}
\end{figure}

Kinetic Energy Contour in Atmospheric Boundary Layer

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Rainbow on St. Anthony Falls