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Diffstat (limited to 'src/include/postgres.h')
| -rw-r--r-- | src/include/postgres.h | 764 |
1 files changed, 764 insertions, 0 deletions
diff --git a/src/include/postgres.h b/src/include/postgres.h new file mode 100644 index 0000000..c48f47e --- /dev/null +++ b/src/include/postgres.h @@ -0,0 +1,764 @@ +/*------------------------------------------------------------------------- + * + * postgres.h + * Primary include file for PostgreSQL server .c files + * + * This should be the first file included by PostgreSQL backend modules. + * Client-side code should include postgres_fe.h instead. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1995, Regents of the University of California + * + * src/include/postgres.h + * + *------------------------------------------------------------------------- + */ +/* + *---------------------------------------------------------------- + * TABLE OF CONTENTS + * + * When adding stuff to this file, please try to put stuff + * into the relevant section, or add new sections as appropriate. + * + * section description + * ------- ------------------------------------------------ + * 1) variable-length datatypes (TOAST support) + * 2) Datum type + support macros + * + * NOTES + * + * In general, this file should contain declarations that are widely needed + * in the backend environment, but are of no interest outside the backend. + * + * Simple type definitions live in c.h, where they are shared with + * postgres_fe.h. We do that since those type definitions are needed by + * frontend modules that want to deal with binary data transmission to or + * from the backend. Type definitions in this file should be for + * representations that never escape the backend, such as Datum or + * TOASTed varlena objects. + * + *---------------------------------------------------------------- + */ +#ifndef POSTGRES_H +#define POSTGRES_H + +#include "c.h" +#include "utils/elog.h" +#include "utils/palloc.h" + +/* ---------------------------------------------------------------- + * Section 1: variable-length datatypes (TOAST support) + * ---------------------------------------------------------------- + */ + +/* + * struct varatt_external is a traditional "TOAST pointer", that is, the + * information needed to fetch a Datum stored out-of-line in a TOAST table. + * The data is compressed if and only if va_extsize < va_rawsize - VARHDRSZ. + * This struct must not contain any padding, because we sometimes compare + * these pointers using memcmp. + * + * Note that this information is stored unaligned within actual tuples, so + * you need to memcpy from the tuple into a local struct variable before + * you can look at these fields! (The reason we use memcmp is to avoid + * having to do that just to detect equality of two TOAST pointers...) + */ +typedef struct varatt_external +{ + int32 va_rawsize; /* Original data size (includes header) */ + int32 va_extsize; /* External saved size (doesn't) */ + Oid va_valueid; /* Unique ID of value within TOAST table */ + Oid va_toastrelid; /* RelID of TOAST table containing it */ +} varatt_external; + +/* + * struct varatt_indirect is a "TOAST pointer" representing an out-of-line + * Datum that's stored in memory, not in an external toast relation. + * The creator of such a Datum is entirely responsible that the referenced + * storage survives for as long as referencing pointer Datums can exist. + * + * Note that just as for struct varatt_external, this struct is stored + * unaligned within any containing tuple. + */ +typedef struct varatt_indirect +{ + struct varlena *pointer; /* Pointer to in-memory varlena */ +} varatt_indirect; + +/* + * struct varatt_expanded is a "TOAST pointer" representing an out-of-line + * Datum that is stored in memory, in some type-specific, not necessarily + * physically contiguous format that is convenient for computation not + * storage. APIs for this, in particular the definition of struct + * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h. + * + * Note that just as for struct varatt_external, this struct is stored + * unaligned within any containing tuple. + */ +typedef struct ExpandedObjectHeader ExpandedObjectHeader; + +typedef struct varatt_expanded +{ + ExpandedObjectHeader *eohptr; +} varatt_expanded; + +/* + * Type tag for the various sorts of "TOAST pointer" datums. The peculiar + * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility + * with a previous notion that the tag field was the pointer datum's length. + */ +typedef enum vartag_external +{ + VARTAG_INDIRECT = 1, + VARTAG_EXPANDED_RO = 2, + VARTAG_EXPANDED_RW = 3, + VARTAG_ONDISK = 18 +} vartag_external; + +/* this test relies on the specific tag values above */ +#define VARTAG_IS_EXPANDED(tag) \ + (((tag) & ~1) == VARTAG_EXPANDED_RO) + +#define VARTAG_SIZE(tag) \ + ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \ + VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \ + (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \ + TrapMacro(true, "unrecognized TOAST vartag")) + +/* + * These structs describe the header of a varlena object that may have been + * TOASTed. Generally, don't reference these structs directly, but use the + * macros below. + * + * We use separate structs for the aligned and unaligned cases because the + * compiler might otherwise think it could generate code that assumes + * alignment while touching fields of a 1-byte-header varlena. + */ +typedef union +{ + struct /* Normal varlena (4-byte length) */ + { + uint32 va_header; + char va_data[FLEXIBLE_ARRAY_MEMBER]; + } va_4byte; + struct /* Compressed-in-line format */ + { + uint32 va_header; + uint32 va_rawsize; /* Original data size (excludes header) */ + char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */ + } va_compressed; +} varattrib_4b; + +typedef struct +{ + uint8 va_header; + char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */ +} varattrib_1b; + +/* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */ +typedef struct +{ + uint8 va_header; /* Always 0x80 or 0x01 */ + uint8 va_tag; /* Type of datum */ + char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */ +} varattrib_1b_e; + +/* + * Bit layouts for varlena headers on big-endian machines: + * + * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G) + * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G) + * 10000000 1-byte length word, unaligned, TOAST pointer + * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b) + * + * Bit layouts for varlena headers on little-endian machines: + * + * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G) + * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G) + * 00000001 1-byte length word, unaligned, TOAST pointer + * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b) + * + * The "xxx" bits are the length field (which includes itself in all cases). + * In the big-endian case we mask to extract the length, in the little-endian + * case we shift. Note that in both cases the flag bits are in the physically + * first byte. Also, it is not possible for a 1-byte length word to be zero; + * this lets us disambiguate alignment padding bytes from the start of an + * unaligned datum. (We now *require* pad bytes to be filled with zero!) + * + * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern + * the specific type and length of the pointer datum. + */ + +/* + * Endian-dependent macros. These are considered internal --- use the + * external macros below instead of using these directly. + * + * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0 + * for such records. Hence you should usually check for IS_EXTERNAL before + * checking for IS_1B. + */ + +#ifdef WORDS_BIGENDIAN + +#define VARATT_IS_4B(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00) +#define VARATT_IS_4B_U(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00) +#define VARATT_IS_4B_C(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40) +#define VARATT_IS_1B(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80) +#define VARATT_IS_1B_E(PTR) \ + ((((varattrib_1b *) (PTR))->va_header) == 0x80) +#define VARATT_NOT_PAD_BYTE(PTR) \ + (*((uint8 *) (PTR)) != 0) + +/* VARSIZE_4B() should only be used on known-aligned data */ +#define VARSIZE_4B(PTR) \ + (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF) +#define VARSIZE_1B(PTR) \ + (((varattrib_1b *) (PTR))->va_header & 0x7F) +#define VARTAG_1B_E(PTR) \ + (((varattrib_1b_e *) (PTR))->va_tag) + +#define SET_VARSIZE_4B(PTR,len) \ + (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF) +#define SET_VARSIZE_4B_C(PTR,len) \ + (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000) +#define SET_VARSIZE_1B(PTR,len) \ + (((varattrib_1b *) (PTR))->va_header = (len) | 0x80) +#define SET_VARTAG_1B_E(PTR,tag) \ + (((varattrib_1b_e *) (PTR))->va_header = 0x80, \ + ((varattrib_1b_e *) (PTR))->va_tag = (tag)) +#else /* !WORDS_BIGENDIAN */ + +#define VARATT_IS_4B(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00) +#define VARATT_IS_4B_U(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00) +#define VARATT_IS_4B_C(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02) +#define VARATT_IS_1B(PTR) \ + ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01) +#define VARATT_IS_1B_E(PTR) \ + ((((varattrib_1b *) (PTR))->va_header) == 0x01) +#define VARATT_NOT_PAD_BYTE(PTR) \ + (*((uint8 *) (PTR)) != 0) + +/* VARSIZE_4B() should only be used on known-aligned data */ +#define VARSIZE_4B(PTR) \ + ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF) +#define VARSIZE_1B(PTR) \ + ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F) +#define VARTAG_1B_E(PTR) \ + (((varattrib_1b_e *) (PTR))->va_tag) + +#define SET_VARSIZE_4B(PTR,len) \ + (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2)) +#define SET_VARSIZE_4B_C(PTR,len) \ + (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02) +#define SET_VARSIZE_1B(PTR,len) \ + (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01) +#define SET_VARTAG_1B_E(PTR,tag) \ + (((varattrib_1b_e *) (PTR))->va_header = 0x01, \ + ((varattrib_1b_e *) (PTR))->va_tag = (tag)) +#endif /* WORDS_BIGENDIAN */ + +#define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data) +#define VARATT_SHORT_MAX 0x7F +#define VARATT_CAN_MAKE_SHORT(PTR) \ + (VARATT_IS_4B_U(PTR) && \ + (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX) +#define VARATT_CONVERTED_SHORT_SIZE(PTR) \ + (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) + +#define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data) + +#define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data) +#define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data) +#define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data) +#define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data) + +#define VARRAWSIZE_4B_C(PTR) \ + (((varattrib_4b *) (PTR))->va_compressed.va_rawsize) + +/* Externally visible macros */ + +/* + * In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(), + * VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR(). Elsewhere, call + * PG_DETOAST_DATUM(), VARDATA() and VARSIZE(). Directly fetching an int16, + * int32 or wider field in the struct representing the datum layout requires + * aligned data. memcpy() is alignment-oblivious, as are most operations on + * datatypes, such as text, whose layout struct contains only char fields. + * + * Code assembling a new datum should call VARDATA() and SET_VARSIZE(). + * (Datums begin life untoasted.) + * + * Other macros here should usually be used only by tuple assembly/disassembly + * code and code that specifically wants to work with still-toasted Datums. + */ +#define VARDATA(PTR) VARDATA_4B(PTR) +#define VARSIZE(PTR) VARSIZE_4B(PTR) + +#define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR) +#define VARDATA_SHORT(PTR) VARDATA_1B(PTR) + +#define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR) +#define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR))) +#define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR) + +#define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR) +#define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR) +#define VARATT_IS_EXTERNAL_ONDISK(PTR) \ + (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK) +#define VARATT_IS_EXTERNAL_INDIRECT(PTR) \ + (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT) +#define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \ + (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO) +#define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \ + (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW) +#define VARATT_IS_EXTERNAL_EXPANDED(PTR) \ + (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR))) +#define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \ + (VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR))) +#define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR) +#define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR)) + +#define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len) +#define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len) +#define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len) + +#define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag) + +#define VARSIZE_ANY(PTR) \ + (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \ + (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \ + VARSIZE_4B(PTR))) + +/* Size of a varlena data, excluding header */ +#define VARSIZE_ANY_EXHDR(PTR) \ + (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \ + (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \ + VARSIZE_4B(PTR)-VARHDRSZ)) + +/* caution: this will not work on an external or compressed-in-line Datum */ +/* caution: this will return a possibly unaligned pointer */ +#define VARDATA_ANY(PTR) \ + (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR)) + + +/* ---------------------------------------------------------------- + * Section 2: Datum type + support macros + * ---------------------------------------------------------------- + */ + +/* + * A Datum contains either a value of a pass-by-value type or a pointer to a + * value of a pass-by-reference type. Therefore, we require: + * + * sizeof(Datum) == sizeof(void *) == 4 or 8 + * + * The macros below and the analogous macros for other types should be used to + * convert between a Datum and the appropriate C type. + */ + +typedef uintptr_t Datum; + +/* + * A NullableDatum is used in places where both a Datum and its nullness needs + * to be stored. This can be more efficient than storing datums and nullness + * in separate arrays, due to better spatial locality, even if more space may + * be wasted due to padding. + */ +typedef struct NullableDatum +{ +#define FIELDNO_NULLABLE_DATUM_DATUM 0 + Datum value; +#define FIELDNO_NULLABLE_DATUM_ISNULL 1 + bool isnull; + /* due to alignment padding this could be used for flags for free */ +} NullableDatum; + +#define SIZEOF_DATUM SIZEOF_VOID_P + +/* + * DatumGetBool + * Returns boolean value of a datum. + * + * Note: any nonzero value will be considered true. + */ + +#define DatumGetBool(X) ((bool) ((X) != 0)) + +/* + * BoolGetDatum + * Returns datum representation for a boolean. + * + * Note: any nonzero value will be considered true. + */ + +#define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0)) + +/* + * DatumGetChar + * Returns character value of a datum. + */ + +#define DatumGetChar(X) ((char) (X)) + +/* + * CharGetDatum + * Returns datum representation for a character. + */ + +#define CharGetDatum(X) ((Datum) (X)) + +/* + * Int8GetDatum + * Returns datum representation for an 8-bit integer. + */ + +#define Int8GetDatum(X) ((Datum) (X)) + +/* + * DatumGetUInt8 + * Returns 8-bit unsigned integer value of a datum. + */ + +#define DatumGetUInt8(X) ((uint8) (X)) + +/* + * UInt8GetDatum + * Returns datum representation for an 8-bit unsigned integer. + */ + +#define UInt8GetDatum(X) ((Datum) (X)) + +/* + * DatumGetInt16 + * Returns 16-bit integer value of a datum. + */ + +#define DatumGetInt16(X) ((int16) (X)) + +/* + * Int16GetDatum + * Returns datum representation for a 16-bit integer. + */ + +#define Int16GetDatum(X) ((Datum) (X)) + +/* + * DatumGetUInt16 + * Returns 16-bit unsigned integer value of a datum. + */ + +#define DatumGetUInt16(X) ((uint16) (X)) + +/* + * UInt16GetDatum + * Returns datum representation for a 16-bit unsigned integer. + */ + +#define UInt16GetDatum(X) ((Datum) (X)) + +/* + * DatumGetInt32 + * Returns 32-bit integer value of a datum. + */ + +#define DatumGetInt32(X) ((int32) (X)) + +/* + * Int32GetDatum + * Returns datum representation for a 32-bit integer. + */ + +#define Int32GetDatum(X) ((Datum) (X)) + +/* + * DatumGetUInt32 + * Returns 32-bit unsigned integer value of a datum. + */ + +#define DatumGetUInt32(X) ((uint32) (X)) + +/* + * UInt32GetDatum + * Returns datum representation for a 32-bit unsigned integer. + */ + +#define UInt32GetDatum(X) ((Datum) (X)) + +/* + * DatumGetObjectId + * Returns object identifier value of a datum. + */ + +#define DatumGetObjectId(X) ((Oid) (X)) + +/* + * ObjectIdGetDatum + * Returns datum representation for an object identifier. + */ + +#define ObjectIdGetDatum(X) ((Datum) (X)) + +/* + * DatumGetTransactionId + * Returns transaction identifier value of a datum. + */ + +#define DatumGetTransactionId(X) ((TransactionId) (X)) + +/* + * TransactionIdGetDatum + * Returns datum representation for a transaction identifier. + */ + +#define TransactionIdGetDatum(X) ((Datum) (X)) + +/* + * MultiXactIdGetDatum + * Returns datum representation for a multixact identifier. + */ + +#define MultiXactIdGetDatum(X) ((Datum) (X)) + +/* + * DatumGetCommandId + * Returns command identifier value of a datum. + */ + +#define DatumGetCommandId(X) ((CommandId) (X)) + +/* + * CommandIdGetDatum + * Returns datum representation for a command identifier. + */ + +#define CommandIdGetDatum(X) ((Datum) (X)) + +/* + * DatumGetPointer + * Returns pointer value of a datum. + */ + +#define DatumGetPointer(X) ((Pointer) (X)) + +/* + * PointerGetDatum + * Returns datum representation for a pointer. + */ + +#define PointerGetDatum(X) ((Datum) (X)) + +/* + * DatumGetCString + * Returns C string (null-terminated string) value of a datum. + * + * Note: C string is not a full-fledged Postgres type at present, + * but type input functions use this conversion for their inputs. + */ + +#define DatumGetCString(X) ((char *) DatumGetPointer(X)) + +/* + * CStringGetDatum + * Returns datum representation for a C string (null-terminated string). + * + * Note: C string is not a full-fledged Postgres type at present, + * but type output functions use this conversion for their outputs. + * Note: CString is pass-by-reference; caller must ensure the pointed-to + * value has adequate lifetime. + */ + +#define CStringGetDatum(X) PointerGetDatum(X) + +/* + * DatumGetName + * Returns name value of a datum. + */ + +#define DatumGetName(X) ((Name) DatumGetPointer(X)) + +/* + * NameGetDatum + * Returns datum representation for a name. + * + * Note: Name is pass-by-reference; caller must ensure the pointed-to + * value has adequate lifetime. + */ + +#define NameGetDatum(X) CStringGetDatum(NameStr(*(X))) + +/* + * DatumGetInt64 + * Returns 64-bit integer value of a datum. + * + * Note: this macro hides whether int64 is pass by value or by reference. + */ + +#ifdef USE_FLOAT8_BYVAL +#define DatumGetInt64(X) ((int64) (X)) +#else +#define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X))) +#endif + +/* + * Int64GetDatum + * Returns datum representation for a 64-bit integer. + * + * Note: if int64 is pass by reference, this function returns a reference + * to palloc'd space. + */ + +#ifdef USE_FLOAT8_BYVAL +#define Int64GetDatum(X) ((Datum) (X)) +#else +extern Datum Int64GetDatum(int64 X); +#endif + +/* + * DatumGetUInt64 + * Returns 64-bit unsigned integer value of a datum. + * + * Note: this macro hides whether int64 is pass by value or by reference. + */ + +#ifdef USE_FLOAT8_BYVAL +#define DatumGetUInt64(X) ((uint64) (X)) +#else +#define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X))) +#endif + +/* + * UInt64GetDatum + * Returns datum representation for a 64-bit unsigned integer. + * + * Note: if int64 is pass by reference, this function returns a reference + * to palloc'd space. + */ + +#ifdef USE_FLOAT8_BYVAL +#define UInt64GetDatum(X) ((Datum) (X)) +#else +#define UInt64GetDatum(X) Int64GetDatum((int64) (X)) +#endif + +/* + * Float <-> Datum conversions + * + * These have to be implemented as inline functions rather than macros, when + * passing by value, because many machines pass int and float function + * parameters/results differently; so we need to play weird games with unions. + */ + +/* + * DatumGetFloat4 + * Returns 4-byte floating point value of a datum. + */ +static inline float4 +DatumGetFloat4(Datum X) +{ + union + { + int32 value; + float4 retval; + } myunion; + + myunion.value = DatumGetInt32(X); + return myunion.retval; +} + +/* + * Float4GetDatum + * Returns datum representation for a 4-byte floating point number. + */ +static inline Datum +Float4GetDatum(float4 X) +{ + union + { + float4 value; + int32 retval; + } myunion; + + myunion.value = X; + return Int32GetDatum(myunion.retval); +} + +/* + * DatumGetFloat8 + * Returns 8-byte floating point value of a datum. + * + * Note: this macro hides whether float8 is pass by value or by reference. + */ + +#ifdef USE_FLOAT8_BYVAL +static inline float8 +DatumGetFloat8(Datum X) +{ + union + { + int64 value; + float8 retval; + } myunion; + + myunion.value = DatumGetInt64(X); + return myunion.retval; +} +#else +#define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X))) +#endif + +/* + * Float8GetDatum + * Returns datum representation for an 8-byte floating point number. + * + * Note: if float8 is pass by reference, this function returns a reference + * to palloc'd space. + */ + +#ifdef USE_FLOAT8_BYVAL +static inline Datum +Float8GetDatum(float8 X) +{ + union + { + float8 value; + int64 retval; + } myunion; + + myunion.value = X; + return Int64GetDatum(myunion.retval); +} +#else +extern Datum Float8GetDatum(float8 X); +#endif + + +/* + * Int64GetDatumFast + * Float8GetDatumFast + * + * These macros are intended to allow writing code that does not depend on + * whether int64 and float8 are pass-by-reference types, while not + * sacrificing performance when they are. The argument must be a variable + * that will exist and have the same value for as long as the Datum is needed. + * In the pass-by-ref case, the address of the variable is taken to use as + * the Datum. In the pass-by-val case, these will be the same as the non-Fast + * macros. + */ + +#ifdef USE_FLOAT8_BYVAL +#define Int64GetDatumFast(X) Int64GetDatum(X) +#define Float8GetDatumFast(X) Float8GetDatum(X) +#else +#define Int64GetDatumFast(X) PointerGetDatum(&(X)) +#define Float8GetDatumFast(X) PointerGetDatum(&(X)) +#endif + +#endif /* POSTGRES_H */ |