/*

  This is a maximally equidistributed combined Tausworthe generator

  based on code from GNU Scientific Library 1.5 (30 Jun 2004)

   x_n = (s1_n ^ s2_n ^ s3_n)

   s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))

   s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))

   s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))

   The period of this generator is about 2^88.

   From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe

   Generators", Mathematics of Computation, 65, 213 (1996), 203--213.

   This is available on the net from L'Ecuyer's home page,

   http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps

   ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps

   There is an erratum in the paper "Tables of Maximally

   Equidistributed Combined LFSR Generators", Mathematics of

   Computation, 68, 225 (1999), 261--269:

   http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps

        ... the k_j most significant bits of z_j must be non-

        zero, for each j. (Note: this restriction also applies to the

        computer code given in [4], but was mistakenly not mentioned in

        that paper.)

   This affects the seeding procedure by imposing the requirement

   s1 > 1, s2 > 7, s3 > 15.

*/

#include <string.h>

#include "rand.h"

#include "pattern.h"

#include "../hash.h"

int arch_random;

static inline uint64_t __seed(uint64_t x, uint64_t m)

{

	return (x < m) ? x + m : x;

}

static void __init_rand32(struct taus88_state *state, unsigned int seed)

{

	int cranks = 6;

#define LCG(x, seed)  ((x) * 69069 ^ (seed))

	state->s1 = __seed(LCG((2^31) + (2^17) + (2^7), seed), 1);

	state->s2 = __seed(LCG(state->s1, seed), 7);

	state->s3 = __seed(LCG(state->s2, seed), 15);

	while (cranks--)

		__rand32(state);

}

static void __init_rand64(struct taus258_state *state, uint64_t seed)

{

	int cranks = 6;

#define LCG64(x, seed)  ((x) * 6906969069ULL ^ (seed))

	state->s1 = __seed(LCG64((2^31) + (2^17) + (2^7), seed), 1);

	state->s2 = __seed(LCG64(state->s1, seed), 7);

	state->s3 = __seed(LCG64(state->s2, seed), 15);

	state->s4 = __seed(LCG64(state->s3, seed), 33);

	state->s5 = __seed(LCG64(state->s4, seed), 49);

	while (cranks--)

		__rand64(state);

}

void init_rand(struct frand_state *state, bool use64)

{

	state->use64 = use64;

	if (!use64)

		__init_rand32(&state->state32, 1);

	else

		__init_rand64(&state->state64, 1);

}

void init_rand_seed(struct frand_state *state, unsigned int seed, bool use64)

{

	state->use64 = use64;

	if (!use64)

		__init_rand32(&state->state32, seed);

	else

		__init_rand64(&state->state64, seed);

}

void __fill_random_buf(void *buf, unsigned int len, uint64_t seed)

{

	void *ptr = buf;

	while (len) {

		int this_len;

		if (len >= sizeof(int64_t)) {

			*((int64_t *) ptr) = seed;

			this_len = sizeof(int64_t);

		} else if (len >= sizeof(int32_t)) {

			*((int32_t *) ptr) = seed;

			this_len = sizeof(int32_t);

		} else if (len >= sizeof(int16_t)) {

			*((int16_t *) ptr) = seed;

			this_len = sizeof(int16_t);

		} else {

			*((int8_t *) ptr) = seed;

			this_len = sizeof(int8_t);

		}

		ptr += this_len;

		len -= this_len;

		seed *= GOLDEN_RATIO_PRIME;

		seed >>= 3;

	}

}

uint64_t fill_random_buf(struct frand_state *fs, void *buf,

			 unsigned int len)

{

	uint64_t r = __rand(fs);

	if (sizeof(int) != sizeof(long *))

		r *= (unsigned long) __rand(fs);

	__fill_random_buf(buf, len, r);

	return r;

}

void __fill_random_buf_percentage(uint64_t seed, void *buf,

				  unsigned int percentage,

				  unsigned int segment, unsigned int len,

				  char *pattern, unsigned int pbytes)

{

	unsigned int this_len;

	if (percentage == 100) {

		if (pbytes)

			(void)cpy_pattern(pattern, pbytes, buf, len);

		else

			memset(buf, 0, len);

		return;

	}

	if (segment > len)

		segment = len;

	while (len) {

		/*

		 * Fill random chunk

		 */

		this_len = ((unsigned long long)segment * (100 - percentage)) / 100;

		if (this_len > len)

			this_len = len;

		__fill_random_buf(buf, this_len, seed);

		len -= this_len;

		if (!len)

			break;

		buf += this_len;

		this_len = segment - this_len;

		if (this_len > len)

			this_len = len;

		else if (len - this_len <= sizeof(long))

			this_len = len;

		if (pbytes)

			(void)cpy_pattern(pattern, pbytes, buf, this_len);

		else

			memset(buf, 0, this_len);

		len -= this_len;

		buf += this_len;

	}

}

uint64_t fill_random_buf_percentage(struct frand_state *fs, void *buf,

				    unsigned int percentage,

				    unsigned int segment, unsigned int len,

				    char *pattern, unsigned int pbytes)

{

	uint64_t r = __rand(fs);

	if (sizeof(int) != sizeof(long *))

		r *= (unsigned long) __rand(fs);

	__fill_random_buf_percentage(r, buf, percentage, segment, len,

					pattern, pbytes);

	return r;

}