/* @(#) swap_bytes.c 1.3 98/07/09 13:40:49 */
/* Copyright (c) 1993 Association of Universities for Research 
 * in Astronomy. All rights reserved. Produced under National   
 * Aeronautics and Space Administration Contract No. NAS5-26555.
 */
/* swap_bytes.c Swap bytes in I*2 data
 *
 * Programmer: R. White     Date: 17 April 1992
 */

/*
 * test to see if byte swapping is necessary on this machine
 */
extern int test_swap()
{
union {
    short s;
    char c[2];
    } u;

    u.c[0] = 0;
    u.c[1] = 1;
    return (u.s != 1);
}

/*
 * swap bytes in pairs in A
 */
extern void swap_bytes(unsigned char a[], int n)
{
int i;
unsigned char tmp;

    for (i=0; i < n-1; i += 2) {
        tmp = a[i];
        a[i] = a[i+1];
        a[i+1] = tmp;
    }
}