#endif /*! _MSC_VER */
-/*
- * Implementation of the Mersenne twister PRNG (pseudo random numer
- * generator). Implementation of MT19937. Has a period of 2^19937-1
- * which is a Mersenne Prime (hence the name).
- *
- * Implemented from specification and original paper:
- * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/ARTICLES/mt.pdf
- *
- * This code is placed in the public domain by me personally
- * (Dale Weiler, a.k.a graphitemaster).
- */
-
-#define MT_SIZE 624
-#define MT_PERIOD 397
-#define MT_SPACE (MT_SIZE - MT_PERIOD)
-
-static uint32_t mt_state[MT_SIZE];
-static size_t mt_index = 0;
-
-static GMQCC_INLINE void mt_generate(void) {
- /*
- * The loop has been unrolled here: the original paper and implemenation
- * Called for the following code:
- * for (register unsigned i = 0; i < MT_SIZE; ++i) {
- * register uint32_t load;
- * load = (0x80000000 & mt_state[i]) // most significant 32nd bit
- * load |= (0x7FFFFFFF & mt_state[(i + 1) % MT_SIZE]) // least significant 31nd bit
- *
- * mt_state[i] = mt_state[(i + MT_PERIOD) % MT_SIZE] ^ (load >> 1);
- *
- * if (load & 1) mt_state[i] ^= 0x9908B0DF;
- * }
- *
- * This essentially is a waste: we have two modulus operations, and
- * a branch that is executed every iteration from [0, MT_SIZE).
- *
- * Please see: http://www.quadibloc.com/crypto/co4814.htm for more
- * information on how this clever trick works.
- */
- static const uint32_t matrix[2] = {
- 0x00000000,
- 0x9908B0Df
- };
- /*
- * This register gives up a little more speed by instructing the compiler
- * to force these into CPU registers (they're counters for indexing mt_state
- * which we can force the compiler to generate prefetch instructions for)
- */
- register uint32_t y;
- register uint32_t i;
-
- /*
- * Said loop has been unrolled for MT_SPACE (226 iterations), opposed
- * to [0, MT_SIZE) (634 iterations).
- */
- for (i = 0; i < MT_SPACE-1; ++i) {
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i + MT_PERIOD] ^ (y >> 1) ^ matrix[y & 1];
-
- i ++; /* loop unroll */
-
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i + MT_PERIOD] ^ (y >> 1) ^ matrix[y & 1];
- }
-
- /*
- * collapsing the walls unrolled (evenly dividing 396 [632-227 = 396
- * = 2*2*3*3*11])
- */
- i = MT_SPACE;
- while (i < MT_SIZE-2) {
- /*
- * We expand this 11 times .. manually, no macros are required
- * here. This all fits in the CPU cache.
- */
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
- mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
- ++i;
- }
-
- /* i = mt_state[623] */
- y = (0x80000000 & mt_state[MT_SIZE - 1]) | (0x7FFFFFFF & mt_state[MT_SIZE - 1]);
- mt_state[MT_SIZE - 1] = mt_state[MT_PERIOD - 1] ^ (y >> 1) ^ matrix[y & 1];
-}
void util_seed(uint32_t value) {
- /*
- * We seed the mt_state with a LCG (linear congruential generator)
- * We're operating exactly on exactly m=32, so there is no need to
- * use modulus.
- *
- * The multipler of choice is 0x6C07865, also knows as the Borosh-
- * Niederreiter multipler used for modulus 2^32. More can be read
- * about this in Knuth's TAOCP Volume 2, page 106.
- *
- * If you don't own TAOCP something is wrong with you :-) .. so I
- * also provided a link to the original paper by Borosh and
- * Niederreiter. It's called "Optional Multipliers for PRNG by The
- * Linear Congruential Method" (1983).
- * http://en.wikipedia.org/wiki/Linear_congruential_generator
- *
- * From said page, it says the following:
- * "A common Mersenne twister implementation, interestingly enough
- * used an LCG to generate seed data."
- *
- * Remarks:
- * The data we're operating on is 32-bits for the mt_state array, so
- * there is no masking required with 0xFFFFFFFF
- */
- register size_t i;
-
- mt_state[0] = value;
- for (i = 1; i < MT_SIZE; ++i)
- mt_state[i] = 0x6C078965 * (mt_state[i - 1] ^ mt_state[i - 1] >> 30) + i;
+ srand((int)value);
}
-
uint32_t util_rand() {
- register uint32_t y;
-
- /*
- * This is inlined with any sane compiler (I checked)
- * for some reason though, SubC seems to be generating invalid
- * code when it inlines this.
- */
- if (!mt_index)
- mt_generate();
-
- y = mt_state[mt_index];
-
- /* Standard tempering */
- y ^= y >> 11; /* +7 */
- y ^= y << 7 & 0x9D2C5680; /* +4 */
- y ^= y << 15 & 0xEFC60000; /* -4 */
- y ^= y >> 18; /* -7 */
-
- if(++mt_index == MT_SIZE)
- mt_index = 0;
-
- return y;
+ return rand();
}
projects / xonotic / gmqcc.git / commitdiff