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/*++
/* NAME
/* format_tv 3
/* SUMMARY
/* format time value with sane precision
/* SYNOPSIS
/* #include <format_tv.h>
/*
/* VSTRING *format_tv(buffer, sec, usec, sig_dig, max_dig)
/* VSTRING *buffer;
/* long sec;
/* long usec;
/* int sig_dig;
/* int max_dig;
/* DESCRIPTION
/* format_tv() formats the specified time as a floating-point
/* number while suppressing irrelevant digits in the output.
/* Large numbers are always rounded up to an integral number
/* of seconds. Small numbers are produced with a limited number
/* of significant digits, provided that the result does not
/* exceed the limit on the total number of digits after the
/* decimal point. Trailing zeros are always omitted from the
/* output.
/*
/* Arguments:
/* .IP buffer
/* The buffer to which the result is appended.
/* .IP sec
/* The seconds portion of the time value.
/* .IP usec
/* The microseconds portion of the time value.
/* .IP sig_dig
/* The maximal number of significant digits when formatting
/* small numbers. Leading nulls don't count as significant,
/* and trailing nulls are not included in the output. Specify
/* a number in the range 1..6.
/* .IP max_dig
/* The maximal number of all digits after the decimal point.
/* Specify a number in the range 0..6.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this
/* software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
#include <sys_defs.h>
/* Utility library. */
#include <msg.h>
#include <format_tv.h>
/* Application-specific. */
#define MILLION 1000000
/* format_tv - print time with limited precision */
VSTRING *format_tv(VSTRING *buf, long sec, long usec,
int sig_dig, int max_dig)
{
static int pow10[] = {1, 10, 100, 1000, 10000, 100000, 1000000};
int n;
int rem;
int wid;
int ures;
/*
* Sanity check.
*/
if (max_dig < 0 || max_dig > 6)
msg_panic("format_tv: bad maximum decimal count %d", max_dig);
if (sec < 0 || usec < 0 || usec > MILLION)
msg_panic("format_tv: bad time %lds %ldus", sec, usec);
if (sig_dig < 1 || sig_dig > 6)
msg_panic("format_tv: bad significant decimal count %d", sig_dig);
ures = MILLION / pow10[max_dig];
wid = pow10[sig_dig];
/*
* Adjust the resolution to suppress irrelevant digits.
*/
if (ures < MILLION) {
if (sec > 0) {
for (n = 1; sec >= n && n <= wid / 10; n *= 10)
/* void */ ;
ures = (MILLION / wid) * n;
} else {
while (usec >= wid * ures)
ures *= 10;
}
}
/*
* Round up the number if necessary. Leave thrash below the resolution.
*/
if (ures > 1) {
usec += ures / 2;
if (usec >= MILLION) {
sec += 1;
usec -= MILLION;
}
}
/*
* Format the number. Truncate trailing null and thrash below resolution.
*/
vstring_sprintf_append(buf, "%ld", sec);
if (usec >= ures) {
VSTRING_ADDCH(buf, '.');
for (rem = usec, n = MILLION / 10; rem >= ures && n > 0; n /= 10) {
VSTRING_ADDCH(buf, "0123456789"[rem / n]);
rem %= n;
}
}
VSTRING_TERMINATE(buf);
return (buf);
}
#ifdef TEST
#include <stdio.h>
#include <stdlib.h>
#include <vstring_vstream.h>
int main(int argc, char **argv)
{
VSTRING *in = vstring_alloc(10);
VSTRING *out = vstring_alloc(10);
double tval;
int sec;
int usec;
int sig_dig;
int max_dig;
while (vstring_get_nonl(in, VSTREAM_IN) > 0) {
vstream_printf(">> %s\n", vstring_str(in));
if (vstring_str(in)[0] == 0 || vstring_str(in)[0] == '#')
continue;
if (sscanf(vstring_str(in), "%lf %d %d", &tval, &sig_dig, &max_dig) != 3)
msg_fatal("bad input: %s", vstring_str(in));
sec = (int) tval; /* raw seconds */
usec = (tval - sec) * MILLION; /* raw microseconds */
VSTRING_RESET(out);
format_tv(out, sec, usec, sig_dig, max_dig);
vstream_printf("%s\n", vstring_str(out));
vstream_fflush(VSTREAM_OUT);
}
vstring_free(in);
vstring_free(out);
return (0);
}
#endif
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