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pg_include/utils/numeric.h

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+/*-------------------------------------------------------------------------
+ *
+ * numeric.h
+ *	  Definitions for the exact numeric data type of Postgres
+ *
+ * Original coding 1998, Jan Wieck.  Heavily revised 2003, Tom Lane.
+ *
+ * Copyright (c) 1998-2012, PostgreSQL Global Development Group
+ *
+ * src/include/utils/numeric.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _PG_NUMERIC_H_
+#define _PG_NUMERIC_H_
+
+#include "fmgr.h"
+
+/*
+ * Hardcoded precision limit - arbitrary, but must be small enough that
+ * dscale values will fit in 14 bits.
+ */
+#define NUMERIC_MAX_PRECISION		1000
+
+/*
+ * Internal limits on the scales chosen for calculation results
+ */
+#define NUMERIC_MAX_DISPLAY_SCALE	NUMERIC_MAX_PRECISION
+#define NUMERIC_MIN_DISPLAY_SCALE	0
+
+#define NUMERIC_MAX_RESULT_SCALE	(NUMERIC_MAX_PRECISION * 2)
+
+/*
+ * For inherently inexact calculations such as division and square root,
+ * we try to get at least this many significant digits; the idea is to
+ * deliver a result no worse than float8 would.
+ */
+#define NUMERIC_MIN_SIG_DIGITS		16
+
+/* The actual contents of Numeric are private to numeric.c */
+struct NumericData;
+typedef struct NumericData *Numeric;
+
+/*
+ * fmgr interface macros
+ */
+
+#define DatumGetNumeric(X)		  ((Numeric) PG_DETOAST_DATUM(X))
+#define DatumGetNumericCopy(X)	  ((Numeric) PG_DETOAST_DATUM_COPY(X))
+#define NumericGetDatum(X)		  PointerGetDatum(X)
+#define PG_GETARG_NUMERIC(n)	  DatumGetNumeric(PG_GETARG_DATUM(n))
+#define PG_GETARG_NUMERIC_COPY(n) DatumGetNumericCopy(PG_GETARG_DATUM(n))
+#define PG_RETURN_NUMERIC(x)	  return NumericGetDatum(x)
+
+/*
+ * Utility functions in numeric.c
+ */
+extern bool numeric_is_nan(Numeric num);
+int32		numeric_maximum_size(int32 typmod);
+extern char *numeric_out_sci(Numeric num, int scale);
+
+#endif   /* _PG_NUMERIC_H_ */