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/* This file, swapproc.c, contains general utility routines that are */
/* used by other FITSIO routines to swap bytes. */
/* The FITSIO software was written by William Pence at the High Energy */
/* Astrophysic Science Archive Research Center (HEASARC) at the NASA */
/* Goddard Space Flight Center. */
#include <string.h>
#include <stdlib.h>
#include "fitsio2.h"
/*--------------------------------------------------------------------------*/
void ffswap2(short *svalues, /* IO - pointer to shorts to be swapped */
long nvals) /* I - number of shorts to be swapped */
/*
swap the bytes in the input short integers: ( 0 1 -> 1 0 )
*/
{
register char *cvalues;
register long ii;
union u_tag {
char cvals[2]; /* equivalence an array of 4 bytes with */
short sval; /* a short */
} u;
cvalues = (char *) svalues; /* copy the initial pointer value */
for (ii = 0; ii < nvals;)
{
u.sval = svalues[ii++]; /* copy next short to temporary buffer */
*cvalues++ = u.cvals[1]; /* copy the 2 bytes to output in turn */
*cvalues++ = u.cvals[0];
}
return;
}
/*--------------------------------------------------------------------------*/
void ffswap4(INT32BIT *ivalues, /* IO - pointer to floats to be swapped */
long nvals) /* I - number of floats to be swapped */
/*
swap the bytes in the input 4-byte integer: ( 0 1 2 3 -> 3 2 1 0 )
*/
{
register char *cvalues;
register long ii;
union u_tag {
char cvals[4]; /* equivalence an array of 4 bytes with */
INT32BIT ival; /* a float */
} u;
cvalues = (char *) ivalues; /* copy the initial pointer value */
for (ii = 0; ii < nvals;)
{
u.ival = ivalues[ii++]; /* copy next float to buffer */
*cvalues++ = u.cvals[3]; /* copy the 4 bytes in turn */
*cvalues++ = u.cvals[2];
*cvalues++ = u.cvals[1];
*cvalues++ = u.cvals[0];
}
return;
}
/*--------------------------------------------------------------------------*/
void ffswap8(double *dvalues, /* IO - pointer to doubles to be swapped */
long nvals) /* I - number of doubles to be swapped */
/*
swap the bytes in the input doubles: ( 01234567 -> 76543210 )
*/
{
register char *cvalues;
register long ii;
register char temp;
cvalues = (char *) dvalues; /* copy the pointer value */
for (ii = 0; ii < nvals*8; ii += 8)
{
temp = cvalues[ii];
cvalues[ii] = cvalues[ii+7];
cvalues[ii+7] = temp;
temp = cvalues[ii+1];
cvalues[ii+1] = cvalues[ii+6];
cvalues[ii+6] = temp;
temp = cvalues[ii+2];
cvalues[ii+2] = cvalues[ii+5];
cvalues[ii+5] = temp;
temp = cvalues[ii+3];
cvalues[ii+3] = cvalues[ii+4];
cvalues[ii+4] = temp;
}
return;
}
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