/*
* *****************************************************************************
*
* Parts of this code are adapted from the following:
*
* PCG, A Family of Better Random Number Generators.
*
* You can find the original source code at:
* https://github.com/imneme/pcg-c
*
* -----------------------------------------------------------------------------
*
* This code is under the following license:
*
* Copyright (c) 2014-2017 Melissa O'Neill and PCG Project contributors
* Copyright (c) 2018-2023 Gavin D. Howard and contributors.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* *****************************************************************************
*
* Definitions for the RNG.
*
*/
#ifndef BC_RAND_H
#define BC_RAND_H
#include <stdint.h>
#include <inttypes.h>
#include <vector.h>
#include <num.h>
#if BC_ENABLE_EXTRA_MATH
#if BC_ENABLE_LIBRARY
#define BC_RAND_USE_FREE (1)
#else // BC_ENABLE_LIBRARY
#if BC_DEBUG
#define BC_RAND_USE_FREE (1)
#else // BC_DEBUG
#define BC_RAND_USE_FREE (0)
#endif // BC_DEBUG
#endif // BC_ENABLE_LIBRARY
/**
* A function to return a random unsigned long.
* @param ptr A void ptr to some data that will help generate the random ulong.
* @return The random ulong.
*/
typedef ulong (*BcRandUlong)(void* ptr);
#if BC_LONG_BIT >= 64
// If longs are 64 bits, we have the option of 128-bit integers on some
// compilers. These two sections test that.
#ifdef BC_RAND_BUILTIN
#if BC_RAND_BUILTIN
#ifndef __SIZEOF_INT128__
#undef BC_RAND_BUILTIN
#define BC_RAND_BUILTIN (0)
#endif // __SIZEOF_INT128__
#endif // BC_RAND_BUILTIN
#endif // BC_RAND_BUILTIN
#ifndef BC_RAND_BUILTIN
#ifdef __SIZEOF_INT128__
#define BC_RAND_BUILTIN (1)
#else // __SIZEOF_INT128__
#define BC_RAND_BUILTIN (0)
#endif // __SIZEOF_INT128__
#endif // BC_RAND_BUILTIN
/// The type for random integers.
typedef uint64_t BcRand;
/// A constant defined by PCG.
#define BC_RAND_ROTC (63)
#if BC_RAND_BUILTIN
/// A typedef for the PCG state.
typedef __uint128_t BcRandState;
/**
* Multiply two integers, worrying about overflow.
* @param a The first integer.
* @param b The second integer.
* @return The product of the PCG states.
*/
#define bc_rand_mul(a, b) (((BcRandState) (a)) * ((BcRandState) (b)))
/**
* Add two integers, worrying about overflow.
* @param a The first integer.
* @param b The second integer.
* @return The sum of the PCG states.
*/
#define bc_rand_add(a, b) (((BcRandState) (a)) + ((BcRandState) (b)))
/**
* Multiply two PCG states.
* @param a The first PCG state.
* @param b The second PCG state.
* @return The product of the PCG states.
*/
#define bc_rand_mul2(a, b) (((BcRandState) (a)) * ((BcRandState) (b)))
/**
* Add two PCG states.
* @param a The first PCG state.
* @param b The second PCG state.
* @return The sum of the PCG states.
*/
#define bc_rand_add2(a, b) (((BcRandState) (a)) + ((BcRandState) (b)))
/**
* Figure out if the PRNG has been modified. Since the increment of the PRNG has
* to be odd, we use the extra bit to store whether it has been modified or not.
* @param r The PRNG.
* @return True if the PRNG has *not* been modified, false otherwise.
*/
#define BC_RAND_NOTMODIFIED(r) (((r)->inc & 1UL) == 0)
/**
* Return true if the PRNG has not been seeded yet.
* @param r The PRNG.
* @return True if the PRNG has not been seeded yet, false otherwise.
*/
#define BC_RAND_ZERO(r) (!(r)->state)
/**
* Returns a constant built from @a h and @a l.
* @param h The high 64 bits.
* @param l The low 64 bits.
* @return The constant built from @a h and @a l.
*/
#define BC_RAND_CONSTANT(h, l) ((((BcRandState) (h)) << 64) + (BcRandState) (l))
/**
* Truncates a PCG state to the number of bits in a random integer.
* @param s The state to truncate.
* @return The truncated state.
*/
#define BC_RAND_TRUNC(s) ((uint64_t) (s))
/**
* Chops a PCG state in half and returns the top bits.
* @param s The state to chop.
* @return The chopped state's top bits.
*/
#define BC_RAND_CHOP(s) ((uint64_t) ((s) >> 64UL))
/**
* Rotates a PCG state.
* @param s The state to rotate.
* @return The rotated state.
*/
#define BC_RAND_ROTAMT(s) ((unsigned int) ((s) >> 122UL))
#else // BC_RAND_BUILTIN
/// A typedef for the PCG state.
typedef struct BcRandState
{
/// The low bits.
uint_fast64_t lo;
/// The high bits.
uint_fast64_t hi;
} BcRandState;
/**
* Multiply two integers, worrying about overflow.
* @param a The first integer.
* @param b The second integer.
* @return The product of the PCG states.
*/
#define bc_rand_mul(a, b) (bc_rand_multiply((a), (b)))
/**
* Add two integers, worrying about overflow.
* @param a The first integer.
* @param b The second integer.
* @return The sum of the PCG states.
*/
#define bc_rand_add(a, b) (bc_rand_addition((a), (b)))
/**
* Multiply two PCG states.
* @param a The first PCG state.
* @param b The second PCG state.
* @return The product of the PCG states.
*/
#define bc_rand_mul2(a, b) (bc_rand_multiply2((a), (b)))
/**
* Add two PCG states.
* @param a The first PCG state.
* @param b The second PCG state.
* @return The sum of the PCG states.
*/
#define bc_rand_add2(a, b) (bc_rand_addition2((a), (b)))
/**
* Figure out if the PRNG has been modified. Since the increment of the PRNG has
* to be odd, we use the extra bit to store whether it has been modified or not.
* @param r The PRNG.
* @return True if the PRNG has *not* been modified, false otherwise.
*/
#define BC_RAND_NOTMODIFIED(r) (((r)->inc.lo & 1) == 0)
/**
* Return true if the PRNG has not been seeded yet.
* @param r The PRNG.
* @return True if the PRNG has not been seeded yet, false otherwise.
*/
#define BC_RAND_ZERO(r) (!(r)->state.lo && !(r)->state.hi)
/**
* Returns a constant built from @a h and @a l.
* @param h The high 64 bits.
* @param l The low 64 bits.
* @return The constant built from @a h and @a l.
*/
#define BC_RAND_CONSTANT(h, l) \
{ \
.lo = (l), .hi = (h) \
}
/**
* Truncates a PCG state to the number of bits in a random integer.
* @param s The state to truncate.
* @return The truncated state.
*/
#define BC_RAND_TRUNC(s) ((s).lo)
/**
* Chops a PCG state in half and returns the top bits.
* @param s The state to chop.
* @return The chopped state's top bits.
*/
#define BC_RAND_CHOP(s) ((s).hi)
/**
* Returns the rotate amount for a PCG state.
* @param s The state to rotate.
* @return The semi-rotated state.
*/
#define BC_RAND_ROTAMT(s) ((unsigned int) ((s).hi >> 58UL))
/// A 64-bit integer with the bottom 32 bits set.
#define BC_RAND_BOTTOM32 (((uint_fast64_t) 0xffffffffULL))
/**
* Returns the 32-bit truncated value of @a n.
* @param n The integer to truncate.
* @return The bottom 32 bits of @a n.
*/
#define BC_RAND_TRUNC32(n) ((n) & (BC_RAND_BOTTOM32))
/**
* Returns the second 32 bits of @a n.
* @param n The integer to truncate.
* @return The second 32 bits of @a n.
*/
#define BC_RAND_CHOP32(n) ((n) >> 32)
#endif // BC_RAND_BUILTIN
/// A constant defined by PCG.
#define BC_RAND_MULTIPLIER \
BC_RAND_CONSTANT(2549297995355413924ULL, 4865540595714422341ULL)
/**
* Returns the result of a PCG fold.
* @param s The state to fold.
* @return The folded state.
*/
#define BC_RAND_FOLD(s) ((BcRand) (BC_RAND_CHOP(s) ^ BC_RAND_TRUNC(s)))
#else // BC_LONG_BIT >= 64
// If we are using 32-bit longs, we need to set these so.
#undef BC_RAND_BUILTIN
#define BC_RAND_BUILTIN (1)
/// The type for random integers.
typedef uint32_t BcRand;
/// A constant defined by PCG.
#define BC_RAND_ROTC (31)
/// A typedef for the PCG state.
typedef uint_fast64_t BcRandState;
/**
* Multiply two integers, worrying about overflow.
* @param a The first integer.
* @param b The second integer.
* @return The product of the PCG states.
*/
#define bc_rand_mul(a, b) (((BcRandState) (a)) * ((BcRandState) (b)))
/**
* Add two integers, worrying about overflow.
* @param a The first integer.
* @param b The second integer.
* @return The sum of the PCG states.
*/
#define bc_rand_add(a, b) (((BcRandState) (a)) + ((BcRandState) (b)))
/**
* Multiply two PCG states.
* @param a The first PCG state.
* @param b The second PCG state.
* @return The product of the PCG states.
*/
#define bc_rand_mul2(a, b) (((BcRandState) (a)) * ((BcRandState) (b)))
/**
* Add two PCG states.
* @param a The first PCG state.
* @param b The second PCG state.
* @return The sum of the PCG states.
*/
#define bc_rand_add2(a, b) (((BcRandState) (a)) + ((BcRandState) (b)))
/**
* Figure out if the PRNG has been modified. Since the increment of the PRNG has
* to be odd, we use the extra bit to store whether it has been modified or not.
* @param r The PRNG.
* @return True if the PRNG has *not* been modified, false otherwise.
*/
#define BC_RAND_NOTMODIFIED(r) (((r)->inc & 1UL) == 0)
/**
* Return true if the PRNG has not been seeded yet.
* @param r The PRNG.
* @return True if the PRNG has not been seeded yet, false otherwise.
*/
#define BC_RAND_ZERO(r) (!(r)->state)
/**
* Returns a constant built from a number.
* @param n The number.
* @return The constant built from @a n.
*/
#define BC_RAND_CONSTANT(n) UINT64_C(n)
/// A constant defined by PCG.
#define BC_RAND_MULTIPLIER BC_RAND_CONSTANT(6364136223846793005)
/**
* Truncates a PCG state to the number of bits in a random integer.
* @param s The state to truncate.
* @return The truncated state.
*/
#define BC_RAND_TRUNC(s) ((uint32_t) (s))
/**
* Chops a PCG state in half and returns the top bits.
* @param s The state to chop.
* @return The chopped state's top bits.
*/
#define BC_RAND_CHOP(s) ((uint32_t) ((s) >> 32UL))
/**
* Returns the rotate amount for a PCG state.
* @param s The state to rotate.
* @return The semi-rotated state.
*/
#define BC_RAND_ROTAMT(s) ((unsigned int) ((s) >> 59UL))
/**
* Returns the result of a PCG fold.
* @param s The state to fold.
* @return The folded state.
*/
#define BC_RAND_FOLD(s) ((BcRand) ((((s) >> 18U) ^ (s)) >> 27U))
#endif // BC_LONG_BIT >= 64
/**
* Rotates @a v by @a r bits.
* @param v The value to rotate.
* @param r The amount to rotate by.
* @return The rotated value.
*/
#define BC_RAND_ROT(v, r) \
((BcRand) (((v) >> (r)) | ((v) << ((0 - (r)) & BC_RAND_ROTC))))
/// The number of bits in a random integer.
#define BC_RAND_BITS (sizeof(BcRand) * CHAR_BIT)
/// The number of bits in a PCG state.
#define BC_RAND_STATE_BITS (sizeof(BcRandState) * CHAR_BIT)
/// The size of a BcNum with the max random integer. This isn't exact; it's
/// actually rather crude. But it's always enough.
#define BC_RAND_NUM_SIZE (BC_NUM_BIGDIG_LOG10 * 2 + 2)
/// The mask for how many bits bc_rand_srand() can set per iteration.
#define BC_RAND_SRAND_BITS ((1 << CHAR_BIT) - 1)
/// The actual RNG data. These are the actual PRNG's.
typedef struct BcRNGData
{
/// The state.
BcRandState state;
/// The increment and the modified bit.
BcRandState inc;
} BcRNGData;
/// The public PRNG. This is just a stack of PRNG's to maintain the globals
/// stack illusion.
typedef struct BcRNG
{
/// The stack of PRNG's.
BcVec v;
} BcRNG;
/**
* Initializes a BcRNG.
* @param r The BcRNG to initialize.
*/
void
bc_rand_init(BcRNG* r);
#if BC_RAND_USE_FREE
/**
* Frees a BcRNG. This is only in debug builds because it would only be freed on
* exit.
* @param r The BcRNG to free.
*/
void
bc_rand_free(BcRNG* r);
#endif // BC_RAND_USE_FREE
/**
* Returns a random integer from the PRNG.
* @param r The PRNG.
* @return A random integer.
*/
BcRand
bc_rand_int(BcRNG* r);
/**
* Returns a random integer from the PRNG bounded by @a bound. Bias is
* eliminated.
* @param r The PRNG.
* @param bound The bound for the random integer.
* @return A bounded random integer.
*/
BcRand
bc_rand_bounded(BcRNG* r, BcRand bound);
/**
* Seed the PRNG with the state in two parts and the increment in two parts.
* @param r The PRNG.
* @param state1 The first part of the state.
* @param state2 The second part of the state.
* @param inc1 The first part of the increment.
* @param inc2 The second part of the increment.
*/
void
bc_rand_seed(BcRNG* r, ulong state1, ulong state2, ulong inc1, ulong inc2);
/**
* Pushes a new PRNG onto the PRNG stack.
* @param r The PRNG.
*/
void
bc_rand_push(BcRNG* r);
/**
* Pops one or all but one items off of the PRNG stack.
* @param r The PRNG.
* @param reset True if all but one PRNG should be popped off the stack, false
* if only one should be popped.
*/
void
bc_rand_pop(BcRNG* r, bool reset);
/**
* Returns, via pointers, the state of the PRNG in pieces.
* @param r The PRNG.
* @param s1 The return value for the first part of the state.
* @param s2 The return value for the second part of the state.
* @param i1 The return value for the first part of the increment.
* @param i2 The return value for the second part of the increment.
*/
void
bc_rand_getRands(BcRNG* r, BcRand* s1, BcRand* s2, BcRand* i1, BcRand* i2);
/**
* Seed the PRNG with random data.
* @param rng The PRNG.
*/
void
bc_rand_srand(BcRNGData* rng);
/// A reference to a constant multiplier.
extern const BcRandState bc_rand_multiplier;
#endif // BC_ENABLE_EXTRA_MATH
#endif // BC_RAND_H
