Revision: 40898
http://brlcad.svn.sourceforge.net/brlcad/?rev=40898&view=rev
Author: erikgreenwald
Date: 2010-10-04 20:47:47 +0000 (Mon, 04 Oct 2010)
Log Message:
-----------
Begin wiring up the mersenne twister stuff to do multiple states with
serialization capabilities.
Modified Paths:
--------------
brlcad/trunk/src/libbn/randmt.c
Modified: brlcad/trunk/src/libbn/randmt.c
===================================================================
--- brlcad/trunk/src/libbn/randmt.c 2010-10-04 14:48:14 UTC (rev 40897)
+++ brlcad/trunk/src/libbn/randmt.c 2010-10-04 20:47:47 UTC (rev 40898)
@@ -50,64 +50,114 @@
#define TEMPERING_SHIFT_T(y) (y << 15)
#define TEMPERING_SHIFT_L(y) (y >> 18)
+#define MERSENNE_MAGIC 0x4D54524E0A
-/* the array for the state vector */
-static unsigned long mt[N];
-/* mti==N+1 means mt[N] is not initialized */
-static int mti=N+1;
+static struct _internal_state_s {
+ uint32_t magic;
+ int mti; /* state index */
+ uint32_t mt[N]; /* state vector */
+} global_state_static = { MERSENNE_MAGIC, N+1 };
+static struct _internal_state_s *global_state = &global_state_static;
+void *
+bn_randmt_state_create()
+{
+ struct _internal_state_s *is;
+
+ is = bu_malloc(sizeof(struct _internal_state_s), "Mersenne Twister state");
+ if(is == NULL)
+ return NULL;
+ is->magic = MERSENNE_MAGIC;
+ is->mti = N+1;
+ return (void *)is;
+}
+
/* initializing the array with a NONZERO seed */
-void bn_randmt_seed(unsigned long seed) {
+void
+bn_randmt_state_seed(struct _internal_state_s *is, uint32_t seed)
+{
/*
* setting initial seeds to mt[N] using
* the generator Line 25 of Table 1 in
* [KNUTH 1981, The Art of Computer Programming
* Vol. 2 (2nd Ed.), pp102]
*/
- mt[0] = seed & 0xffffffff;
- for (mti = 1; mti<N; mti++)
- mt[mti] = (69069 * mt[mti-1]) & 0xffffffff;
+ is->mt[0] = seed & 0xffffffff;
+ for (is->mti = 1; is->mti<N; is->mti++)
+ is->mt[is->mti] = (69069 * is->mt[is->mti-1]) & 0xffffffff;
}
+double
+bn_randmt_state(struct _internal_state_s *is)
+{
+ uint32_t y;
+ static uint32_t mag01[2]={0x0, MATRIX_A};
-double bn_randmt() {
- unsigned long y;
- static unsigned long mag01[2]={0x0, MATRIX_A};
-
/* generate N words at one time */
- if (mti >= N) {
+ if (is->mti >= N) {
int kk;
/* if sgenrand() has not been called, a default initial seed is used */
- if (mti == N+1)
+ if (is->mti == N+1)
bn_randmt_seed(4357);
for (kk = 0; kk < N-M; kk++) {
- y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
- mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];
+ y = (is->mt[kk]&UPPER_MASK)|(is->mt[kk+1]&LOWER_MASK);
+ is->mt[kk] = is->mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];
}
for (; kk < N-1; kk++) {
- y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
- mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];
+ y = (is->mt[kk]&UPPER_MASK)|(is->mt[kk+1]&LOWER_MASK);
+ is->mt[kk] = is->mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];
}
- y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
- mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];
+ y = (is->mt[N-1]&UPPER_MASK)|(is->mt[0]&LOWER_MASK);
+ is->mt[N-1] = is->mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];
- mti = 0;
+ is->mti = 0;
}
- y = mt[mti++];
+ y = is->mt[is->mti++];
y ^= TEMPERING_SHIFT_U(y);
y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
y ^= TEMPERING_SHIFT_L(y);
- return (double)y / (unsigned long)0xffffffff;
+ return (double)y / (uint32_t)0xffffffff;
}
+/* straight binhex would result in a 8+4992 character encoding. We should be
able
+ * to compress it quite a bit with better encoding? maybe uuencode? */
+void
+bn_randmt_state_serialize(struct _internal_state_s *is, struct bu_vls *s)
+{
+ bu_bomb("Not implemented yet.\n");
+}
+
+void
+bn_randmt_state_deserialize(struct _internal_state_s *is, struct bu_vls *s)
+{
+ bu_bomb("Not implemented yet.\n");
+}
+
+void
+bn_rand_mt_state_set_global(struct _internal_state_s *is)
+{
+ global_state = is;
+}
+
+void
+bn_randmt_seed(unsigned long seed)
+{
+ bn_randmt_state_seed(global_state, (uint32_t)seed);
+}
+
+double bn_randmt()
+{
+ return bn_randmt_state(global_state);
+}
+
/*
* Local Variables:
* mode: C
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