/* return 1 if get extra field */

int parseextra(heads * hdr,char * p,int len)
{
 int code;
 int slen;

 while(len>4)
 {
  code=*p++;
  code+=(*p++)<<8;

  slen=*p++;
  slen+=(*p++)<<8;

  if(code==0x4341)   /* a hit */
  {
   if(!memcmp(p,"ARC0",4))
   {                                    // DP 1/11/2007
    hdr->load=makelong((byte*)(p+4));
    hdr->exec=makelong((byte*)(p+8));
    hdr->acc=makelong((byte*)(p+12));
    if(len==20 || len==24) return(2);   // DP 1/11/2007 it is a SparkFS header and contains nothing else
    return(1);
   }                                    // DP 1/11/2007
  }
  p+=slen;
  len-=slen+4;
 }
 return(0);
}


static int writeextra(heads * hdr,char * p)
{
 int len;

 len=4+16; /* was +4; */

 *p++=0x41;
 *p++=0x43;
 *p++=len;
 *p++=len>>8;
 *p++='A';
 *p++='R';
 *p++='C';
 *p++='0';

 unmakelong((byte*)p,hdr->load);
 p+=4;

 unmakelong((byte*)p,hdr->exec);
 p+=4;

 unmakelong((byte*)p,hdr->acc);
 p+=4;

 unmakelong((byte*)p,0);
 p+=4;

 return(len+4);  /* was len */
}