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Repair inconsistent rounding behavior for timestamp, time, interval,

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per gripe from Csaba Nagy.  There is still potential for platform-specific
behavior for values that are exactly halfway between integers, but at
least we now get the expected answer for all other cases.
This commit is contained in:
Tom Lane
2003-01-09 01:06:57 +00:00
parent 2cd00f0bac
commit fb715e05f5
2 changed files with 56 additions and 105 deletions
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57
src/backend/utils/adt/date.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.74 2002/11/21 23:31:20 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.75 2003/01/09 01:06:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -630,12 +630,12 @@ AdjustTimeForTypmod(TimeADT *time, int32 typmod)
};
static const int64 TimeOffsets[MAX_TIMESTAMP_PRECISION + 1] = {
INT64CONST(-500000),
INT64CONST(-50000),
INT64CONST(-5000),
INT64CONST(-500),
INT64CONST(-50),
INT64CONST(-5),
INT64CONST(500000),
INT64CONST(50000),
INT64CONST(5000),
INT64CONST(500),
INT64CONST(50),
INT64CONST(5),
INT64CONST(0)
};
@@ -649,52 +649,33 @@ AdjustTimeForTypmod(TimeADT *time, int32 typmod)
100000,
1000000
};
static const double TimeOffsets[MAX_TIMESTAMP_PRECISION + 1] = {
0.5,
0.05,
0.005,
0.0005,
0.00005,
0.000005,
0.0000005
};
#endif
if ((typmod >= 0) && (typmod <= MAX_TIME_PRECISION))
{
/*
* Note: this round-to-nearest code is not completely consistent
* about rounding values that are exactly halfway between integral
* values. On most platforms, rint() will implement round-to-nearest,
* but the integer code always rounds up (away from zero). Is it
* worth trying to be consistent?
*/
#ifdef HAVE_INT64_TIMESTAMP
/* we have different truncation behavior depending on sign */
if (*time >= INT64CONST(0))
{
*time = ((*time / TimeScales[typmod])
* TimeScales[typmod]);
}
else
{
*time = (((*time + TimeOffsets[typmod]) / TimeScales[typmod])
* TimeScales[typmod]);
}
#else
/* we have different truncation behavior depending on sign */
if (*time >= 0)
{
*time = (rint(((double) *time) * TimeScales[typmod])
/ TimeScales[typmod]);
}
else
{
/*
* Scale and truncate first, then add to help the rounding
* behavior
*/
*time = (rint((((double) *time) * TimeScales[typmod]) + TimeOffsets[typmod])
/ TimeScales[typmod]);
*time = - ((((- *time) + TimeOffsets[typmod]) / TimeScales[typmod])
* TimeScales[typmod]);
}
#else
*time = (rint(((double) *time) * TimeScales[typmod])
/ TimeScales[typmod]);
#endif
}
return;
}