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Member "ntp-4.2.8p15/libntp/timexsup.c" (23 Jun 2020, 1194 Bytes) of package /linux/misc/ntp-4.2.8p15.tar.gz:

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    1 /*
    2  * timexsup.c - 'struct timex' support functions
    3  *
    4  * Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project.
    5  * The contents of 'html/copyright.html' apply.
    6  */
    7 
    8 #include "config.h"
    9 #include "timexsup.h"
   10 #include <limits.h>
   11 #include <math.h>
   12 
   13 #ifdef HAVE_SYS_TIMEX_H
   14 # include <sys/timex.h>
   15 #endif
   16 
   17 #if defined(MOD_NANO) != defined(STA_NANO)
   18 # warning inconsistent definitions of MOD_NANO vs STA_NANO
   19 #endif
   20 
   21 static long
   22 clamp_rounded(
   23     double dval
   24     )
   25 {
   26     /* round */
   27     dval = floor(dval + 0.5);
   28 
   29     /* clamp / saturate */
   30     if (dval >= (double)LONG_MAX)
   31         return LONG_MAX;
   32     if (dval <= (double)LONG_MIN)
   33         return LONG_MIN;
   34     return (long)dval;
   35 }
   36 
   37 double
   38 dbl_from_var_long(
   39     long    lval,
   40     int status
   41     )
   42 {
   43 #ifdef STA_NANO
   44     if (status & STA_NANO)
   45         return (double)lval * 1e-9;
   46 #else
   47     (void)status;
   48 #endif
   49     return (double)lval * 1e-6;
   50 }
   51 
   52 double
   53 dbl_from_usec_long(
   54     long    lval
   55     )
   56 {
   57     return (double)lval * 1e-6;
   58 }
   59 
   60 long
   61 var_long_from_dbl(
   62     double      dval,
   63     unsigned int *  modes
   64     )
   65 {
   66 #ifdef MOD_NANO
   67     *modes |= MOD_NANO;
   68     dval *= 1e+9;
   69 #else
   70     (void)modes;
   71     dval *= 1e+6;
   72 #endif
   73     return clamp_rounded(dval);
   74 }
   75 
   76 long
   77 usec_long_from_dbl(
   78     double  dval
   79     )
   80 {
   81     return clamp_rounded(dval * 1e+6);
   82 }