#
#include <cvl/cvl.h>
/*
 * IRHEAD inputs a CVL picture header from the specified file descriptor.
 * The length of the comment field is returned, unless an error occurs,
 * in which case -1 is returned.
 * this is exactly IHEAD except that reverse byte order is expected.
 * Joseph Pallas        9/18/80         cc -O -c ihead.c
 * Modified by Robert L. Kirby for more distinctive tag1 on Oct 8, 1980.
 */

int irhead (fdin, oldarea)
int fdin;
struct cvl_p *oldarea;
{
	register int numread;
	register int total;
	register char *p;
		 short flipshort();

	p = (char *)oldarea;
	for(total = 0; total < sizeof *oldarea; total += numread)
	if((numread = read(fdin, &p[total], sizeof *oldarea - total)) == 0
	     || numread == -1)
		return(-1);
	if(oldarea->cv_tag != 'PICT' + 0x80)
		return(-1);
	oldarea->cv_lcom = flipshort(oldarea->cv_lcom);
	oldarea->cv_type = flipshort(oldarea->cv_type);
	oldarea->cv_dims = flipshort(oldarea->cv_dims);
	oldarea->cv_hpls = flipshort(oldarea->cv_hpls);
	oldarea->cv_plns = flipshort(oldarea->cv_plns);
	oldarea->cv_rows = flipshort(oldarea->cv_rows);
	oldarea->cv_cols = flipshort(oldarea->cv_cols);
	oldarea->cv_bnds = flipshort(oldarea->cv_bnds);
	oldarea->cv_bp   = flipshort(oldarea->cv_bp);
	oldarea->cv_ebb  = flipshort(oldarea->cv_ebb);
	oldarea->cv_sbb  = flipshort(oldarea->cv_sbb);
	oldarea->cv_bb   = flipshort(oldarea->cv_bb);
	oldarea->cv_sbp  = flipshort(oldarea->cv_sbp);
	oldarea->cv_ebp  = flipshort(oldarea->cv_ebp);
	return(oldarea->cv_lcom);
}

static short flipshort(invalue)
   short invalue;
{
   short outvalue;
   char *in, *out;

   in = (char *) (&invalue);
   out = (char *) (&outvalue);

   in[0] = out[1];
   in[1] = out[0];

   return(outvalue);
}