external/ibm-public/postfix/dist/src/util/format_tv.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      format_tv 3
   6 /* SUMMARY
   7 /*      format time value with sane precision
   8 /* SYNOPSIS
   9 /*      #include <format_tv.h>
  10 /*
  11 /*      VSTRING *format_tv(buffer, sec, usec, sig_dig, max_dig)
  12 /*      VSTRING *buffer;
  13 /*      int     sec;
  14 /*      int     usec;
  15 /*      int     sig_dig;
  16 /*      int     max_dig;
  17 /* DESCRIPTION
  18 /*      format_tv() formats the specified time as a floating-point
  19 /*      number while suppressing irrelevant digits in the output.
  20 /*      Large numbers are always rounded up to an integral number
  21 /*      of seconds. Small numbers are produced with a limited number
  22 /*      of significant digits, provided that the result does not
  23 /*      exceed the limit on the total number of digits after the
  24 /*      decimal point.  Trailing zeros are always omitted from the
  25 /*      output.
  26 /*
  27 /*      Arguments:
  28 /* .IP buffer
  29 /*      The buffer to which the result is appended.
  30 /* .IP sec
  31 /*      The seconds portion of the time value.
  32 /* .IP usec
  33 /*      The microseconds portion of the time value.
  34 /* .IP sig_dig
  35 /*      The maximal number of significant digits when formatting
  36 /*      small numbers. Leading nulls don't count as significant,
  37 /*      and trailing nulls are not included in the output.  Specify
  38 /*      a number in the range 1..6.
  39 /* .IP max_dig
  40 /*      The maximal number of all digits after the decimal point.
  41 /*      Specify a number in the range 0..6.
  42 /* LICENSE
  43 /* .ad
  44 /* fi
  45 /*      The Secure Mailer license must be distributed with this
  46 /*      software.
  47 /* AUTHOR(S)
  48 /*      Wietse Venema
  49 /*      IBM T.J. Watson Research
  50 /*      P.O. Box 704
  51 /*      Yorktown Heights, NY 10598, USA
  52 /*--*/
  53
  54 #include <sys_defs.h>
  55
  56 /* Utility library. */
  57
  58 #include <msg.h>
  59 #include <format_tv.h>
  60
  61 /* Application-specific. */
  62
  63 #define MILLION 1000000
  64
  65 /* format_tv - print time with limited precision */
  66
  67 VSTRING *format_tv(VSTRING *buf, int sec, int usec,
  68                            int sig_dig, int max_dig)
  69 {
  70     static int pow10[] = {1, 10, 100, 1000, 10000, 100000, 1000000};
  71     int     n;
  72     int     rem;
  73     int     wid;
  74     int     ures;
  75
  76     /*
  77      * Sanity check.
  78      */
  79     if (max_dig < 0 || max_dig > 6)
  80         msg_panic("format_tv: bad maximum decimal count %d", max_dig);
  81     if (sec < 0 || usec < 0 || usec > MILLION)
  82         msg_panic("format_tv: bad time %ds %dus", sec, usec);
  83     if (sig_dig < 1 || sig_dig > 6)
  84         msg_panic("format_tv: bad significant decimal count %d", sig_dig);
  85     ures = MILLION / pow10[max_dig];
  86     wid = pow10[sig_dig];
  87
  88     /*
  89      * Adjust the resolution to suppress irrelevant digits.
  90      */
  91     if (ures < MILLION) {
  92         if (sec > 0) {
  93             for (n = 1; sec >= n && n <= wid / 10; n *= 10)
  94                  /* void */ ;
  95             ures = (MILLION / wid) * n;
  96         } else {
  97             while (usec >= wid * ures)
  98                 ures *= 10;
  99         }
 100     }
 101
 102     /*
 103      * Round up the number if necessary. Leave thrash below the resolution.
 104      */
 105     if (ures > 1) {
 106         usec += ures / 2;
 107         if (usec >= MILLION) {
 108             sec += 1;
 109             usec -= MILLION;
 110         }
 111     }
 112
 113     /*
 114      * Format the number. Truncate trailing null and thrash below resolution.
 115      */
 116     vstring_sprintf_append(buf, "%d", sec);
 117     if (usec >= ures) {
 118         VSTRING_ADDCH(buf, '.');
 119         for (rem = usec, n = MILLION / 10; rem >= ures && n > 0; n /= 10) {
 120             VSTRING_ADDCH(buf, "0123456789"[rem / n]);
 121             rem %= n;
 122         }
 123     }
 124     VSTRING_TERMINATE(buf);
 125     return (buf);
 126 }
 127
 128 #ifdef TEST
 129
 130 #include <stdio.h>
 131 #include <stdlib.h>
 132 #include <vstring_vstream.h>
 133
 134 int     main(int argc, char **argv)
 135 {
 136     VSTRING *in = vstring_alloc(10);
 137     VSTRING *out = vstring_alloc(10);
 138     double  tval;
 139     int     sec;
 140     int     usec;
 141     int     sig_dig;
 142     int     max_dig;
 143
 144     while (vstring_get_nonl(in, VSTREAM_IN) > 0) {
 145         vstream_printf(">> %s\n", vstring_str(in));
 146         if (vstring_str(in)[0] == 0 || vstring_str(in)[0] == '#')
 147             continue;
 148         if (sscanf(vstring_str(in), "%lf %d %d", &tval, &sig_dig, &max_dig) != 3)
 149             msg_fatal("bad input: %s", vstring_str(in));
 150         sec = (int) tval;                       /* raw seconds */
 151         usec = (tval - sec) * MILLION;          /* raw microseconds */
 152         VSTRING_RESET(out);
 153         format_tv(out, sec, usec, sig_dig, max_dig);
 154         vstream_printf("%s\n", vstring_str(out));
 155         vstream_fflush(VSTREAM_OUT);
 156     }
 157     vstring_free(in);
 158     vstring_free(out);
 159     return (0);
 160 }
 161
 162 #endif