dist/ntp/libntp/tsftomsu.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * tsftomsu - convert from a time stamp fraction to milliseconds
   5  */
   6 #include "ntp_fp.h"
   7 #include "ntp_stdlib.h"
   8
   9 int
  10 tsftomsu(
  11         u_long tsf,
  12         int round
  13         )
  14 {
  15         register long val_ui, val_uf;
  16         register long tmp_ui, tmp_uf;
  17         register int i;
  18
  19         /*
  20          * Essentially, multiply by 10 three times in l_fp form.
  21          * The integral part is the milliseconds.
  22          */
  23         val_ui = 0;
  24         val_uf = tsf;
  25         for (i = 3; i > 0; i--) {
  26                 M_LSHIFT(val_ui, val_uf);
  27                 tmp_ui = val_ui;
  28                 tmp_uf = val_uf;
  29                 M_LSHIFT(val_ui, val_uf);
  30                 M_LSHIFT(val_ui, val_uf);
  31                 M_ADD(val_ui, val_uf, tmp_ui, tmp_uf);
  32         }
  33
  34         /*
  35          * Round the value if need be, then return it.
  36          */
  37         if (round && (val_uf & 0x80000000))
  38             val_ui++;
  39         return (int)val_ui;
  40 }