1 /*-------------------------------------------------------------------------
4 * Definitions for the exact numeric data type of Postgres
6 * Original coding 1998, Jan Wieck. Heavily revised 2003, Tom Lane.
8 * Copyright (c) 1998-2003, PostgreSQL Global Development Group
10 * $Id: numeric.h,v 1.17 2003/03/21 01:58:05 tgl Exp $
12 *-------------------------------------------------------------------------
14 #ifndef _PG_NUMERIC_H_
15 #define _PG_NUMERIC_H_
18 * Hardcoded precision limit - arbitrary, but must be small enough that
19 * dscale values will fit in 14 bits.
21 #define NUMERIC_MAX_PRECISION 1000
24 * Internal limits on the scales chosen for calculation results
26 #define NUMERIC_MAX_DISPLAY_SCALE NUMERIC_MAX_PRECISION
27 #define NUMERIC_MIN_DISPLAY_SCALE 0
29 #define NUMERIC_MAX_RESULT_SCALE (NUMERIC_MAX_PRECISION * 2)
32 * For inherently inexact calculations such as division and square root,
33 * we try to get at least this many significant digits; the idea is to
34 * deliver a result no worse than float8 would.
36 #define NUMERIC_MIN_SIG_DIGITS 16
40 * Sign values and macros to deal with packing/unpacking n_sign_dscale
42 #define NUMERIC_SIGN_MASK 0xC000
43 #define NUMERIC_POS 0x0000
44 #define NUMERIC_NEG 0x4000
45 #define NUMERIC_NAN 0xC000
46 #define NUMERIC_DSCALE_MASK 0x3FFF
47 #define NUMERIC_SIGN(n) ((n)->n_sign_dscale & NUMERIC_SIGN_MASK)
48 #define NUMERIC_DSCALE(n) ((n)->n_sign_dscale & NUMERIC_DSCALE_MASK)
49 #define NUMERIC_IS_NAN(n) (NUMERIC_SIGN(n) != NUMERIC_POS && \
50 NUMERIC_SIGN(n) != NUMERIC_NEG)
54 * The Numeric data type stored in the database
56 * NOTE: by convention, values in the packed form have been stripped of
57 * all leading and trailing zero digits (where a "digit" is of base NBASE).
58 * In particular, if the value is zero, there will be no digits at all!
59 * The weight is arbitrary in that case, but we normally set it to zero.
61 typedef struct NumericData
63 int32 varlen; /* Variable size (std varlena header) */
64 int16 n_weight; /* Weight of 1st digit */
65 uint16 n_sign_dscale; /* Sign + display scale */
66 char n_data[1]; /* Digits (really array of NumericDigit) */
69 typedef NumericData *Numeric;
71 #define NUMERIC_HDRSZ (sizeof(int32) + sizeof(int16) + sizeof(uint16))
75 * fmgr interface macros
78 #define DatumGetNumeric(X) ((Numeric) PG_DETOAST_DATUM(X))
79 #define DatumGetNumericCopy(X) ((Numeric) PG_DETOAST_DATUM_COPY(X))
80 #define NumericGetDatum(X) PointerGetDatum(X)
81 #define PG_GETARG_NUMERIC(n) DatumGetNumeric(PG_GETARG_DATUM(n))
82 #define PG_GETARG_NUMERIC_COPY(n) DatumGetNumericCopy(PG_GETARG_DATUM(n))
83 #define PG_RETURN_NUMERIC(x) return NumericGetDatum(x)
85 #endif /* _PG_NUMERIC_H_ */