/** 
 * @file  SFMT.c
 * @brief SIMD oriented Fast Mersenne Twister(SFMT)
 *
 * @author Mutsuo Saito (Hiroshima University)
 * @author Makoto Matsumoto (Hiroshima University)
 *
 * Copyright (C) 2006,2007 Mutsuo Saito, Makoto Matsumoto and Hiroshima
 * University. All rights reserved.
 *
 * The new BSD License is applied to this software, see LICENSE.txt
 */

import std.c.time: time, time_t;
extern(C) { void * memset ( void * ptr, int value, size_t num ); }

/** 
 * @file SFMT.h 
 *
 * @brief SIMD oriented Fast Mersenne Twister(SFMT) pseudorandom
 * number generator
 *
 * @author Mutsuo Saito (Hiroshima University)
 * @author Makoto Matsumoto (Hiroshima University)
 *
 * Copyright (C) 2006, 2007 Mutsuo Saito, Makoto Matsumoto and Hiroshima
 * University. All rights reserved.
 *
 * The new BSD License is applied to this software.
 * see LICENSE.txt
 *
 * @note We assume that your system has inttypes.h.  If your system
 * doesn't have inttypes.h, you have to typedef uint32_t and uint64_t,
 * and you have to define PRIu64 and PRIx64 in this file as follows:
 * @verbatim
 typedef unsigned int uint32_t
 typedef unsigned long long uint64_t  
 #define PRIu64 "llu"
 #define PRIx64 "llx"
@endverbatim
 * uint32_t must be exactly 32-bit unsigned integer type (no more, no
 * less), and uint64_t must be exactly 64-bit unsigned integer type.
 * PRIu64 and PRIx64 are used for printf function to print 64-bit
 * unsigned int and 64-bit unsigned int in hexadecimal format.
 */

alias uint  uint32_t;
alias ulong uint64_t;

/* These real versions are due to Isaku Wada */
/** generates a random number on [0,1]-real-interval */
static double to_real1(uint32_t v)
{
    return v * (1.0/4294967295.0); 
    /* divided by 2^32-1 */ 
}

/** generates a random number on [0,1]-real-interval */
static double genrand_real1()
{
    return to_real1(gen_rand32());
}

/** generates a random number on [0,1)-real-interval */
static double to_real2(uint32_t v)
{
    return v * (1.0/4294967296.0); 
    /* divided by 2^32 */
}

/** generates a random number on [0,1)-real-interval */
static double genrand_real2()
{
    return to_real2(gen_rand32());
}

/** generates a random number on (0,1)-real-interval */
static double to_real3(uint32_t v)
{
    return ((cast(double)v) + 0.5)*(1.0/4294967296.0); 
    /* divided by 2^32 */
}

/** generates a random number on (0,1)-real-interval */
static double genrand_real3()
{
    return to_real3(gen_rand32());
}
/** These real versions are due to Isaku Wada */

/** generates a random number on [0,1) with 53-bit resolution*/
static double to_res53(uint64_t v) 
{ 
    return v * (1.0/18446744073709551616.0L);
}

/** generates a random number on [0,1) with 53-bit resolution from two
 * 32 bit integers */
static double to_res53_mix(uint32_t x, uint32_t y) 
{ 
    return to_res53(x | (cast(uint64_t)y << 32));
}

/** generates a random number on [0,1) with 53-bit resolution
 */
static double genrand_res53() 
{ 
    return to_res53(gen_rand64());
} 

/** generates a random number on [0,1) with 53-bit resolution
    using 32bit integer.
 */
static double genrand_res53_mix() 
{ 
    uint32_t x, y;

    x = gen_rand32();
    y = gen_rand32();
    return to_res53_mix(x, y);
} 

//// start of SSMT-params.h
const int MEXP = 19937;

/*-----------------
  BASIC DEFINITIONS
  -----------------*/
/** Mersenne Exponent. The period of the sequence 
 *  is a multiple of 2^MEXP-1.
 * #define MEXP 19937 */
/** SFMT generator has an internal state array of 128-bit integers,
 * and N is its size. */
auto int N;
static this() { N = (MEXP / 128 + 1); }

/** N32 is the size of internal state array when regarded as an array
 * of 32-bit integers.*/
auto int N32;
static this() { N32 = (N * 4); }

/** N64 is the size of internal state array when regarded as an array
 * of 64-bit integers.*/
auto int N64;
static this() { N64 = (N * 2); }

/*----------------------
  the parameters of SFMT
  following definitions are in paramsXXXX.h file.
  ----------------------*/
/** the pick up position of the array.
#define POS1 122 
*/

/** the parameter of shift left as four 32-bit registers.
#define SL1 18
 */

/** the parameter of shift left as one 128-bit register. 
 * The 128-bit integer is shifted by (SL2 * 8) bits. 
#define SL2 1 
*/

/** the parameter of shift right as four 32-bit registers.
#define SR1 11
*/

/** the parameter of shift right as one 128-bit register. 
 * The 128-bit integer is shifted by (SL2 * 8) bits. 
#define SR2 1 
*/

/** A bitmask, used in the recursion.  These parameters are introduced
 * to break symmetry of SIMD.
#define MSK1 0xdfffffefU
#define MSK2 0xddfecb7fU
#define MSK3 0xbffaffffU
#define MSK4 0xbffffff6U 
*/

/** These definitions are part of a 128-bit period certification vector.
#define PARITY1	0x00000001U
#define PARITY2	0x00000000U
#define PARITY3	0x00000000U
#define PARITY4	0xc98e126aU
*/

const uint POS1 = 122;
const uint SL1  = 18;
const uint SL2  = 1;
const uint SR1  = 11;
const uint SR2  = 1;
const uint MSK1 = 0xdfffffefU;
const uint MSK2 = 0xddfecb7fU;
const uint MSK3 = 0xbffaffffU;
const uint MSK4 = 0xbffffff6U;
const uint PARITY1 = 0x00000001U;
const uint PARITY2 = 0x00000000U;
const uint PARITY3 = 0x00000000U;
const uint PARITY4 = 0x13c9e684U;

/+
/* PARAMETERS FOR ALTIVEC */
#if defined(__APPLE__)	/* For OSX */
#else
    #define ALTI_SL1	{SL1, SL1, SL1, SL1}
    #define ALTI_SR1	{SR1, SR1, SR1, SR1}
    #define ALTI_MSK	{MSK1, MSK2, MSK3, MSK4}
    #define ALTI_MSK64	{MSK2, MSK1, MSK4, MSK3}
    #define ALTI_SL2_PERM	{1,2,3,23,5,6,7,0,9,10,11,4,13,14,15,8}
    #define ALTI_SL2_PERM64	{1,2,3,4,5,6,7,31,9,10,11,12,13,14,15,0}
    #define ALTI_SR2_PERM	{7,0,1,2,11,4,5,6,15,8,9,10,17,12,13,14}
    #define ALTI_SR2_PERM64	{15,0,1,2,3,4,5,6,17,8,9,10,11,12,13,14}
#endif	/* For OSX */
#define IDSTR	"SFMT-19937:122-18-1-11-1:dfffffef-ddfecb7f-bffaffff-bffffff6"
+/

//// start of sfmt.c
/*------------------------------------------------------
  128-bit SIMD data type for Altivec, SSE2 or standard C
  ------------------------------------------------------*/
/** 128-bit data structure */

struct W128_T {
    uint32_t u[4];
};
/** 128-bit data type */
alias W128_T w128_t;

/*--------------------------------------
  FILE GLOBAL VARIABLES
  internal state, index counter and flag 
  --------------------------------------*/
/** the 128-bit internal state array */
w128_t sfmt[(MEXP / 128 + 1)];
/** the 32bit integer pointer to the 128-bit internal state array */
static uint32_t* psfmt32;
static this() { psfmt32 = cast(uint32_t *)&sfmt[0].u[0]; }
/** the 64bit integer pointer to the 128-bit internal state array */
static uint64_t *psfmt64;
static this() { psfmt64 = cast(uint64_t *)&sfmt[0].u[0]; }

/** index counter to the 32-bit internal state array */
static int idx;
/** a flag: it is 0 if and only if the internal state is not yet
 * initialized. */
static int initialized = 0;
/** a parity check vector which certificate the period of 2^{MEXP} */
static uint32_t parity[4] = [0x00000001U, 0x00000000U, 0x00000000U, 0x13c9e684U];

/*----------------
  STATIC FUNCTIONS
  ----------------*/

/**
 * This function simulate a 64-bit index of LITTLE ENDIAN 
 * in BIG ENDIAN machine.
 */
static int idxof(int i) {
    return i;
}

/**
 * This function simulates SIMD 128-bit right shift by the standard C.
 * The 128-bit integer given in in is shifted by (shift * 8) bits.
 * This function simulates the LITTLE ENDIAN SIMD.
 * @param output the output of this function
 * @param in the 128-bit data to be shifted
 * @param shift the shift value
 */
static void rshift128(out w128_t output, w128_t input, int shift) {
    uint64_t th, tl, oh, ol;

    th = (cast(uint64_t)input.u[3] << 32) | (cast(uint64_t)input.u[2]);
    tl = (cast(uint64_t)input.u[1] << 32) | (cast(uint64_t)input.u[0]);

    oh = th >> (shift * 8);
    ol = tl >> (shift * 8);
    ol |= th << (64 - shift * 8);
    output.u[1] = cast(uint32_t)(ol >> 32);
    output.u[0] = cast(uint32_t)ol;
    output.u[3] = cast(uint32_t)(oh >> 32);
    output.u[2] = cast(uint32_t)oh;
}

/**
 * This function simulates SIMD 128-bit left shift by the standard C.
 * The 128-bit integer given in in is shifted by (shift * 8) bits.
 * This function simulates the LITTLE ENDIAN SIMD.
 * @param output the output of this function
 * @param in the 128-bit data to be shifted
 * @param shift the shift value
 */

static void lshift128(out w128_t output, in w128_t input, int shift) {
    uint64_t th, tl, oh, ol;

    th = (cast(uint64_t)input.u[3] << 32) | (cast(uint64_t)input.u[2]);
    tl = (cast(uint64_t)input.u[1] << 32) | (cast(uint64_t)input.u[0]);

    oh = th << (shift * 8);
    ol = tl << (shift * 8);
    oh |= tl >> (64 - shift * 8);
    output.u[1] = cast(uint32_t)(ol >> 32);
    output.u[0] = cast(uint32_t)ol;
    output.u[3] = cast(uint32_t)(oh >> 32);
    output.u[2] = cast(uint32_t)oh;
}

/**
 * This function represents the recursion formula.
 * @param r output
 * @param a a 128-bit part of the internal state array
 * @param b a 128-bit part of the internal state array
 * @param c a 128-bit part of the internal state array
 * @param d a 128-bit part of the internal state array
 */
static void do_recursion(out w128_t r, w128_t a, w128_t b, w128_t c,
				w128_t d) {
    w128_t x;
    w128_t y;

    lshift128(x, a, 1);
    rshift128(y, c, 1);
    r.u[0] = a.u[0] ^ x.u[0] ^ ((b.u[0] >> 11) & 0xdfffffefU) ^ y.u[0] 
	^ (d.u[0] << 18);
    r.u[1] = a.u[1] ^ x.u[1] ^ ((b.u[1] >> 11) & 0xddfecb7fU) ^ y.u[1] 
	^ (d.u[1] << 18);
    r.u[2] = a.u[2] ^ x.u[2] ^ ((b.u[2] >> 11) & 0xbffaffffU) ^ y.u[2] 
	^ (d.u[2] << 18);
    r.u[3] = a.u[3] ^ x.u[3] ^ ((b.u[3] >> 11) & 0xbffffff6U) ^ y.u[3] 
	^ (d.u[3] << 18);
}

/**
 * This function fills the internal state array with pseudorandom
 * integers.
 */
static void gen_rand_all() {
    int i;
    w128_t r1, r2;

    r1 = sfmt[(MEXP / 128 + 1) - 2];
    r2 = sfmt[(MEXP / 128 + 1) - 1];
    for (i = 0; i < (MEXP / 128 + 1) - 122; i++) {
	do_recursion(sfmt[i], sfmt[i], sfmt[i + 122], r1, r2);
	r1 = r2;
	r2 = sfmt[i];
    }
    for (; i < (MEXP / 128 + 1); i++) {
	do_recursion(sfmt[i], sfmt[i], sfmt[i + 122 - (MEXP / 128 + 1)], r1, r2);
	r1 = r2;
	r2 = sfmt[i];
    }
}

/**
 * This function fills the user-specified array with pseudorandom
 * integers.
 *
 * @param array an 128-bit array to be filled by pseudorandom numbers.  
 * @param size number of 128-bit pseudorandom numbers to be generated.
 */
static void gen_rand_array(w128_t *array, int size) {
    int i, j;
    w128_t r1, r2;

    r1 = sfmt[(MEXP / 128 + 1) - 2];
    r2 = sfmt[(MEXP / 128 + 1) - 1];
    for (i = 0; i < (MEXP / 128 + 1) - 122; i++) {
	do_recursion(array[i], sfmt[i], sfmt[i + 122], r1, r2);
	r1 = r2;
	r2 = array[i];
    }
    for (; i < (MEXP / 128 + 1); i++) {
	do_recursion(array[i], sfmt[i], array[i + 122 - (MEXP / 128 + 1)], r1, r2);
	r1 = r2;
	r2 = array[i];
    }
    for (; i < size - (MEXP / 128 + 1); i++) {
	do_recursion(array[i], array[i - (MEXP / 128 + 1)], array[i + 122 - (MEXP / 128 + 1)], r1, r2);
	r1 = r2;
	r2 = array[i];
    }
    for (j = 0; j < 2 * (MEXP / 128 + 1) - size; j++) {
	sfmt[j] = array[j + size - (MEXP / 128 + 1)];
    }
    for (; i < size; i++, j++) {
	do_recursion(array[i], array[i - (MEXP / 128 + 1)], array[i + 122 - (MEXP / 128 + 1)], r1, r2);
	r1 = r2;
	r2 = array[i];
	sfmt[j] = array[i];
    }
}

/**
 * This function represents a function used in the initialization
 * by init_by_array
 * @param x 32-bit integer
 * @return 32-bit integer
 */
static uint32_t func1(uint32_t x) {
    return (x ^ (x >> 27)) * cast(uint32_t)1664525UL;
}

/**
 * This function represents a function used in the initialization
 * by init_by_array
 * @param x 32-bit integer
 * @return 32-bit integer
 */
static uint32_t func2(uint32_t x) {
    return (x ^ (x >> 27)) * cast(uint32_t)1566083941UL;
}

/**
 * This function certificate the period of 2^{MEXP}
 */
static void period_certification() {
    int inner = 0;
    int i, j;
    uint32_t work;

    for (i = 0; i < 4; i++)
	inner ^= psfmt32[idxof(i)] & parity[i];
    for (i = 16; i > 0; i >>= 1)
	inner ^= inner >> i;
    inner &= 1;
    /* check OK */
    if (inner == 1) {
	return;
    }
    /* check NG, and modification */
    for (i = 0; i < 4; i++) {
	work = 1;
	for (j = 0; j < 32; j++) {
	    if ((work & parity[i]) != 0) {
		psfmt32[idxof(i)] ^= work;
		return;
	    }
	    work = work << 1;
	}
    }
}

/*----------------
  PUBLIC FUNCTIONS
  ----------------*/
/**
 * This function returns the identification string.
 * The string shows the word size, the Mersenne exponent,
 * and all parameters of this generator.
 */
const char[] get_idstring() {
    return "SFMT-19937:122-18-1-11-1:dfffffef-ddfecb7f-bffaffff-bffffff6".dup;
}

/**
 * This function returns the minimum size of array used for \b
 * fill_array32() function.
 * @return minimum size of array used for fill_array32() function.
 */
int get_min_array_size32() {
    return ((MEXP / 128 + 1) * 4);
}

/**
 * This function returns the minimum size of array used for \b
 * fill_array64() function.
 * @return minimum size of array used for fill_array64() function.
 */
int get_min_array_size64() {
    return ((MEXP / 128 + 1) * 2);
}

/**
 * This function generates and returns 32-bit pseudorandom number.
 * init_gen_rand or init_by_array must be called before this function.
 * @return 32-bit pseudorandom number
 */
uint32_t gen_rand32() {
    uint32_t r;

    assert(initialized);
    if (idx >= ((MEXP / 128 + 1) * 4)) {
	gen_rand_all();
	idx = 0;
    }
    r = psfmt32[idx++];
    return r;
}

/**
 * This function generates and returns 64-bit pseudorandom number.
 * init_gen_rand or init_by_array must be called before this function.
 * The function gen_rand64 should not be called after gen_rand32,
 * unless an initialization is again executed. 
 * @return 64-bit pseudorandom number
 */
uint64_t gen_rand64() {
    uint64_t r;
    assert(initialized);
    assert(idx % 2 == 0);

    if (idx >= ((MEXP / 128 + 1) * 4)) {
	gen_rand_all();
	idx = 0;
    }
    r = psfmt64[idx / 2];
    idx += 2;
    return r;
}

/**
 * This function generates pseudorandom 32-bit integers in the
 * specified array[] by one call. The number of pseudorandom integers
 * is specified by the argument size, which must be at least 624 and a
 * multiple of four.  The generation by this function is much faster
 * than the following gen_rand function.
 *
 * For initialization, init_gen_rand or init_by_array must be called
 * before the first call of this function. This function can not be
 * used after calling gen_rand function, without initialization.
 *
 * @param array an array where pseudorandom 32-bit integers are filled
 * by this function.  The pointer to the array must be \b "aligned"
 * (namely, must be a multiple of 16) in the SIMD version, since it
 * refers to the address of a 128-bit integer.  In the standard C
 * version, the pointer is arbitrary.
 *
 * @param size the number of 32-bit pseudorandom integers to be
 * generated.  size must be a multiple of 4, and greater than or equal
 * to (MEXP / 128 + 1) * 4.
 *
 * @note \b memalign or \b posix_memalign is available to get aligned
 * memory. Mac OSX doesn't have these functions, but \b malloc of OSX
 * returns the pointer to the aligned memory block.
 */
void fill_array32(uint32_t *array, int size) {
	  assert(initialized);
    assert(idx == ((MEXP / 128 + 1) * 4));
    assert(size % 4 == 0);
    assert(size >= ((MEXP / 128 + 1) * 4));

    gen_rand_array(cast(w128_t*)array, size / 4);
    idx = ((MEXP / 128 + 1) * 4);
}

/**
 * This function generates pseudorandom 64-bit integers in the
 * specified array[] by one call. The number of pseudorandom integers
 * is specified by the argument size, which must be at least 312 and a
 * multiple of two.  The generation by this function is much faster
 * than the following gen_rand function.
 *
 * For initialization, init_gen_rand or init_by_array must be called
 * before the first call of this function. This function can not be
 * used after calling gen_rand function, without initialization.
 *
 * @param array an array where pseudorandom 64-bit integers are filled
 * by this function.  The pointer to the array must be "aligned"
 * (namely, must be a multiple of 16) in the SIMD version, since it
 * refers to the address of a 128-bit integer.  In the standard C
 * version, the pointer is arbitrary.
 *
 * @param size the number of 64-bit pseudorandom integers to be
 * generated.  size must be a multiple of 2, and greater than or equal
 * to (MEXP / 128 + 1) * 2
 *
 * @note \b memalign or \b posix_memalign is available to get aligned
 * memory. Mac OSX doesn't have these functions, but \b malloc of OSX
 * returns the pointer to the aligned memory block.
 */
void fill_array64(uint64_t* array, int size) {
	assert(initialized);
    assert(idx == ((MEXP / 128 + 1) * 4));
    assert(size % 2 == 0);
    assert(size >= ((MEXP / 128 + 1) * 2));

    gen_rand_array(cast(w128_t *)array, size / 2);
    idx = ((MEXP / 128 + 1) * 4);
}

/**
 * This function initializes the internal state array with a 32-bit
 * integer seed.
 *
 * @param seed a 32-bit integer used as the seed.
 */
void init_gen_rand(uint32_t seed) {
    int i;
	  psfmt32[idxof(0)] = seed;
    for (i = 1; i < ((MEXP / 128 + 1) * 4); i++) {
	  psfmt32[idxof(i)] = 1812433253UL * (psfmt32[idxof(i - 1)] 
					    ^ (psfmt32[idxof(i - 1)] >> 30))
	    + i;
    }
    idx = ((MEXP / 128 + 1) * 4);
    period_certification();
    initialized = 1;
}

static this() { init_gen_rand(jsw_time_seed()); }

/**
 * This function initializes the internal state array,
 * with an array of 32-bit integers used as the seeds
 * @param init_key the array of 32-bit integers, used as a seed.
 * @param key_length the length of init_key.
 */
void init_by_array(uint32_t[] init_key, int key_length) {
    int i, j, count;
    uint32_t r;
    int lag;
    int mid;
    int size = (MEXP / 128 + 1) * 4;

    if (size >= 623) {
	lag = 11;
    } else if (size >= 68) {
	lag = 7;
    } else if (size >= 39) {
	lag = 5;
    } else {
	lag = 3;
    }
    mid = (size - lag) / 2;

    memset(cast(void*)sfmt, 0x8b, sfmt.sizeof);
    //sfmt[0 .. sfmt.sizeof] = cast(int)0x8b;
    if (key_length + 1 > ((MEXP / 128 + 1) * 4)) {
	count = key_length + 1;
    } else {
	count = ((MEXP / 128 + 1) * 4);
    }
    r = func1(psfmt32[idxof(0)] ^ psfmt32[idxof(mid)] 
	      ^ psfmt32[idxof(((MEXP / 128 + 1) * 4) - 1)]);
    psfmt32[idxof(mid)] += r;
    r += key_length;
    psfmt32[idxof(mid + lag)] += r;
    psfmt32[idxof(0)] = r;

    count--;
    for (i = 1, j = 0; (j < count) && (j < key_length); j++) {
	r = func1(psfmt32[idxof(i)] ^ psfmt32[idxof((i + mid) % ((MEXP / 128 + 1) * 4))] 
		  ^ psfmt32[idxof((i + ((MEXP / 128 + 1) * 4) - 1) % ((MEXP / 128 + 1) * 4))]);
	psfmt32[idxof((i + mid) % ((MEXP / 128 + 1) * 4))] += r;
	r += init_key[j] + i;
	psfmt32[idxof((i + mid + lag) % ((MEXP / 128 + 1) * 4))] += r;
	psfmt32[idxof(i)] = r;
	i = (i + 1) % ((MEXP / 128 + 1) * 4);
    }
    for (; j < count; j++) {
	r = func1(psfmt32[idxof(i)] ^ psfmt32[idxof((i + mid) % ((MEXP / 128 + 1) * 4))] 
		  ^ psfmt32[idxof((i + ((MEXP / 128 + 1) * 4) - 1) % ((MEXP / 128 + 1) * 4))]);
	psfmt32[idxof((i + mid) % ((MEXP / 128 + 1) * 4))] += r;
	r += i;
	psfmt32[idxof((i + mid + lag) % ((MEXP / 128 + 1) * 4))] += r;
	psfmt32[idxof(i)] = r;
	i = (i + 1) % ((MEXP / 128 + 1) * 4);
    }
    for (j = 0; j < ((MEXP / 128 + 1) * 4); j++) {
	r = func2(psfmt32[idxof(i)] + psfmt32[idxof((i + mid) % ((MEXP / 128 + 1) * 4))] 
		  + psfmt32[idxof((i + ((MEXP / 128 + 1) * 4) - 1) % ((MEXP / 128 + 1) * 4))]);
	psfmt32[idxof((i + mid) % ((MEXP / 128 + 1) * 4))] ^= r;
	r -= i;
	psfmt32[idxof((i + mid + lag) % ((MEXP / 128 + 1) * 4))] ^= r;
	psfmt32[idxof(i)] = r;
	i = (i + 1) % ((MEXP / 128 + 1) * 4);
    }

    idx = ((MEXP / 128 + 1) * 4);
    period_certification();
    initialized = 1;
}

/* Portable time seed */
uint32_t jsw_time_seed()
{
  time_t now = time ( null );
  ubyte* p = cast(ubyte*)&now;
  uint32_t seed = 0;
  size_t i;
  
  for ( i = 0; i < now.sizeof; i++ )
    seed = seed * ( ubyte.max + 2U ) + p[i];
    
  return seed;
}