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Make details of the Numeric representation private to numeric.c.

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Review by Tom Lane.
This commit is contained in:
Robert Haas
2010-07-30 04:30:23 +00:00
parent f223bb7a41
commit 8a4dc94ca0
4 changed files with 75 additions and 50 deletions
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65
src/backend/utils/adt/numeric.c
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@ -14,7 +14,7 @@
* Copyright (c) 1998-2010, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.123 2010/02/26 02:01:09 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.124 2010/07/30 04:30:23 rhaas Exp $
*
*-------------------------------------------------------------------------
*/
@ -35,6 +35,38 @@
#include "utils/int8.h"
#include "utils/numeric.h"
/*
* Sign values and macros to deal with packing/unpacking n_sign_dscale
*/
#define NUMERIC_SIGN_MASK 0xC000
#define NUMERIC_POS 0x0000
#define NUMERIC_NEG 0x4000
#define NUMERIC_NAN 0xC000
#define NUMERIC_DSCALE_MASK 0x3FFF
#define NUMERIC_SIGN(n) ((n)->n_sign_dscale & NUMERIC_SIGN_MASK)
#define NUMERIC_DSCALE(n) ((n)->n_sign_dscale & NUMERIC_DSCALE_MASK)
#define NUMERIC_IS_NAN(n) (NUMERIC_SIGN(n) != NUMERIC_POS && \
NUMERIC_SIGN(n) != NUMERIC_NEG)
#define NUMERIC_HDRSZ (VARHDRSZ + sizeof(uint16) + sizeof(int16))
/*
* The Numeric data type stored in the database
*
* NOTE: by convention, values in the packed form have been stripped of
* all leading and trailing zero digits (where a "digit" is of base NBASE).
* In particular, if the value is zero, there will be no digits at all!
* The weight is arbitrary in that case, but we normally set it to zero.
*/
struct NumericData
{
int32 vl_len_; /* varlena header (do not touch directly!) */
uint16 n_sign_dscale; /* Sign + display scale */
int16 n_weight; /* Weight of 1st digit */
char n_data[1]; /* Digits (really array of NumericDigit) */
};
/* ----------
* Uncomment the following to enable compilation of dump_numeric()
* and dump_var() and to get a dump of any result produced by make_result().
@ -427,6 +459,37 @@ numeric_out(PG_FUNCTION_ARGS)
PG_RETURN_CSTRING(str);
}
/*
* numeric_is_nan() -
*
* Is Numeric value a NaN?
*/
bool
numeric_is_nan(Numeric num)
{
return NUMERIC_IS_NAN(num);
}
/*
* numeric_maximum_size() -
*
* Maximum size of a numeric with given typmod, or -1 if unlimited/unknown.
*/
int32
numeric_maximum_size(int32 typemod)
{
int precision;
if (typemod <= VARHDRSZ)
return -1;
/* precision (ie, max # of digits) is in upper bits of typmod */
precision = ((typemod - VARHDRSZ) >> 16) & 0xffff;
/* Numeric stores 2 decimal digits/byte, plus header */
return (precision + 1) / 2 + NUMERIC_HDRSZ;
}
/*
* numeric_out_sci() -
*