-#include "rand.h"
+/*
+ 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
-struct frand_state __fio_rand_state;
+ ... 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 "rand.h"
+#include "../hash.h"
static inline int __seed(unsigned int x, unsigned int m)
{
return (x < m) ? x + m : x;
}
+static void __init_rand(struct frand_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--)
+ __rand(state);
+}
+
void init_rand(struct frand_state *state)
{
-#define LCG(x) ((x) * 69069) /* super-duper LCG */
-
- state->s1 = __seed(LCG((2^31) + (2^17) + (2^7)), 1);
- state->s2 = __seed(LCG(state->s1), 7);
- state->s3 = __seed(LCG(state->s2), 15);
-
- __rand(state);
- __rand(state);
- __rand(state);
- __rand(state);
- __rand(state);
- __rand(state);
+ __init_rand(state, 1);
+}
+
+void init_rand_seed(struct frand_state *state, unsigned int seed)
+{
+ __init_rand(state, seed);
+}
+
+void __fill_random_buf(void *buf, unsigned int len, unsigned long seed)
+{
+ long *ptr = buf;
+
+ while ((void *) ptr - buf < len) {
+ *ptr = seed;
+ ptr++;
+ seed *= GOLDEN_RATIO_PRIME;
+ seed >>= 3;
+ }
+}
+
+unsigned long fill_random_buf(struct frand_state *fs, void *buf,
+ unsigned int len)
+{
+ unsigned long r = __rand(fs);
+
+ if (sizeof(int) != sizeof(long *))
+ r *= (unsigned long) __rand(fs);
+
+ __fill_random_buf(buf, len, r);
+ return r;
}