#include "dcltng.h"

unsigned short lt_shrt ( int endianness, unsigned char *bullx, int *ibxptr )

/************************************************************************
 * lt_shrt                                                              *
 *                                                                      *
 * This routine reads two bytes as an unsigned short from the given	* 
 * bulletin.  The byte ordering can be big-endian or little-endian and	*
 * is specified during input.						*
 *                                                                      *
 * Input parameters:                                                    *
 *	ENDIANNESS	INT	Byte-ordering scheme within bulletin:	*
 *				  0 = big-endian			*
 *				  1 = little-endian			*
 *	BULLX		CHAR*	Lightning bulletin			*
 *	IBXPTR		INT*	Pointer within BULLX			*
 *                                                                      *
 * Output parameters:							*
 *	IBXPTR		INT*	Updated pointer within BULLX		*
 *	LT_SHRT		USHRT*	Unsigned short value			*
 **                                                                     *
 * Log:                                                                 *
 * S. Guan/NCEP         10/08  Initial version                          *
 * S. Guan/NCEP         01/09   Reconstruct                             *
 * J. Ator/NCEP		10/13	Read from bullx instead of stdin	*
 * J. Ator/NCEP		04/15	Added endianness argument		*
 ***********************************************************************/

{
    static unsigned short shrt_bit_shifts[2][2] = {
	{  8,  0 }, /* successive bit shifts when reading as big-endian */
	{  0,  8 }  /* successive bit shifts when reading as little-endian */
    };

    unsigned short result = 0;
    unsigned char  in;
    unsigned short ii;

    for ( ii = 0; ii < 2; ii++ ) {
	in = (unsigned char) bullx[++(*ibxptr)];
	result += in << shrt_bit_shifts[endianness][ii];
    }

    return result;
}