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/*-------------------------------------------------------------------------
*
* Pseudo-Random Number Generator
*
* Copyright (c) 2021-2022, PostgreSQL Global Development Group
*
* src/include/common/pg_prng.h
*
*-------------------------------------------------------------------------
*/
#ifndef PG_PRNG_H
#define PG_PRNG_H
/*
* State vector for PRNG generation. Callers should treat this as an
* opaque typedef, but we expose its definition to allow it to be
* embedded in other structs.
*/
typedef struct pg_prng_state
{
uint64 s0,
s1;
} pg_prng_state;
/*
* Callers not needing local PRNG series may use this global state vector,
* after initializing it with one of the pg_prng_...seed functions.
*/
extern PGDLLIMPORT pg_prng_state pg_global_prng_state;
extern void pg_prng_seed(pg_prng_state *state, uint64 seed);
extern void pg_prng_fseed(pg_prng_state *state, double fseed);
extern bool pg_prng_seed_check(pg_prng_state *state);
/*
* Initialize the PRNG state from the pg_strong_random source,
* taking care that we don't produce all-zeroes. If this returns false,
* caller should initialize the PRNG state from some other random seed,
* using pg_prng_[f]seed.
*
* We implement this as a macro, so that the pg_strong_random() call is
* in the caller. If it were in pg_prng.c, programs using pg_prng.c
* but not needing strong seeding would nonetheless be forced to pull in
* pg_strong_random.c and thence OpenSSL.
*/
#define pg_prng_strong_seed(state) \
(pg_strong_random((void *) (state), sizeof(pg_prng_state)) ? \
pg_prng_seed_check(state) : false)
extern uint64 pg_prng_uint64(pg_prng_state *state);
extern uint64 pg_prng_uint64_range(pg_prng_state *state, uint64 rmin, uint64 rmax);
extern int64 pg_prng_int64(pg_prng_state *state);
extern int64 pg_prng_int64p(pg_prng_state *state);
extern uint32 pg_prng_uint32(pg_prng_state *state);
extern int32 pg_prng_int32(pg_prng_state *state);
extern int32 pg_prng_int32p(pg_prng_state *state);
extern double pg_prng_double(pg_prng_state *state);
extern bool pg_prng_bool(pg_prng_state *state);
#endif /* PG_PRNG_H */
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