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) 1998-2007, PostgreSQL Global Development Group
10 * $PostgreSQL: pgsql/src/include/utils/numeric.h,v 1.24 2007/02/27 23:48:10 tgl Exp $
12 *-------------------------------------------------------------------------
14 #ifndef _PG_NUMERIC_H_
15 #define _PG_NUMERIC_H_
20 * Hardcoded precision limit - arbitrary, but must be small enough that
21 * dscale values will fit in 14 bits.
23 #define NUMERIC_MAX_PRECISION 1000
26 * Internal limits on the scales chosen for calculation results
28 #define NUMERIC_MAX_DISPLAY_SCALE NUMERIC_MAX_PRECISION
29 #define NUMERIC_MIN_DISPLAY_SCALE 0
31 #define NUMERIC_MAX_RESULT_SCALE (NUMERIC_MAX_PRECISION * 2)
34 * For inherently inexact calculations such as division and square root,
35 * we try to get at least this many significant digits; the idea is to
36 * deliver a result no worse than float8 would.
38 #define NUMERIC_MIN_SIG_DIGITS 16
42 * Sign values and macros to deal with packing/unpacking n_sign_dscale
44 #define NUMERIC_SIGN_MASK 0xC000
45 #define NUMERIC_POS 0x0000
46 #define NUMERIC_NEG 0x4000
47 #define NUMERIC_NAN 0xC000
48 #define NUMERIC_DSCALE_MASK 0x3FFF
49 #define NUMERIC_SIGN(n) ((n)->n_sign_dscale & NUMERIC_SIGN_MASK)
50 #define NUMERIC_DSCALE(n) ((n)->n_sign_dscale & NUMERIC_DSCALE_MASK)
51 #define NUMERIC_IS_NAN(n) (NUMERIC_SIGN(n) != NUMERIC_POS && \
52 NUMERIC_SIGN(n) != NUMERIC_NEG)
56 * The Numeric data type stored in the database
58 * NOTE: by convention, values in the packed form have been stripped of
59 * all leading and trailing zero digits (where a "digit" is of base NBASE).
60 * In particular, if the value is zero, there will be no digits at all!
61 * The weight is arbitrary in that case, but we normally set it to zero.
63 typedef struct NumericData
65 int32 vl_len_; /* varlena header (do not touch directly!) */
66 int16 n_weight; /* Weight of 1st digit */
67 uint16 n_sign_dscale; /* Sign + display scale */
68 char n_data[1]; /* Digits (really array of NumericDigit) */
71 typedef NumericData *Numeric;
73 #define NUMERIC_HDRSZ (VARHDRSZ + sizeof(int16) + sizeof(uint16))
77 * fmgr interface macros
80 #define DatumGetNumeric(X) ((Numeric) PG_DETOAST_DATUM(X))
81 #define DatumGetNumericCopy(X) ((Numeric) PG_DETOAST_DATUM_COPY(X))
82 #define NumericGetDatum(X) PointerGetDatum(X)
83 #define PG_GETARG_NUMERIC(n) DatumGetNumeric(PG_GETARG_DATUM(n))
84 #define PG_GETARG_NUMERIC_COPY(n) DatumGetNumericCopy(PG_GETARG_DATUM(n))
85 #define PG_RETURN_NUMERIC(x) return NumericGetDatum(x)
87 #endif /* _PG_NUMERIC_H_ */