/*      $NetBSD: refidsmear.c,v 1.2 2020/05/25 20:47:24 christos Exp $  */

#include <config.h>

#include <ntp.h>
#include <ntp_fp.h>
#include <refidsmear.h>

/*
* we want to test a refid format of:
* 254.x.y.x
*
* where x.y.z are 24 bits containing 2 (signed) integer bits
* and 22 fractional bits.
*
*/


l_fp
convertRefIDToLFP(uint32_t r)
{
       l_fp temp;

       r = ntohl(r);

       // printf("%03d %08x: ", (r >> 24) & 0xFF, (r & 0x00FFFFFF) );

       temp.l_uf = (r << 10);  /* 22 fractional bits */

       temp.l_ui = (r >> 22) & 0x3;
       temp.l_ui |= ~(temp.l_ui & 2) + 1;

       return temp;
}


uint32_t
convertLFPToRefID(l_fp num)
{
       uint32_t temp;

       /* round the input with the highest bit to shift out from the
        * fraction, then keep just two bits from the integral part.
        *
        * TODO: check for overflows; should we clamp/saturate or just
        * complain?
        */
       L_ADDUF(&num, 0x200);
       num.l_ui &= 3;

       /* combine integral and fractional part to 24 bits */
       temp  = (num.l_ui << 22) | (num.l_uf >> 10);

       /* put in the leading 254.0.0.0 */
       temp |= UINT32_C(0xFE000000);

       // printf("%03d %08x: ", (temp >> 24) & 0xFF, (temp & 0x00FFFFFF) );

       return htonl(temp);
}