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Comparing deliantra/server/include/util.h (file contents):
Revision 1.81 by root, Fri Dec 26 10:36:42 2008 UTC vs.
Revision 1.84 by root, Wed Dec 31 17:35:37 2008 UTC

… …
41#endif 41#endif
42 42
43// put into ifs if you are very sure that the expression 43// put into ifs if you are very sure that the expression
44// is mostly true or mosty false. note that these return 44// is mostly true or mosty false. note that these return
45// booleans, not the expression. 45// booleans, not the expression.
46#define expect_false(expr) expect ((expr) != 0, 0) 46#define expect_false(expr) expect ((expr) ? 1 : 0, 0)
47#define expect_true(expr) expect ((expr) != 0, 1) 47#define expect_true(expr) expect ((expr) ? 1 : 0, 1)
48 48
49#include <pthread.h> 49#include <pthread.h>
50 50
51#include <cstddef> 51#include <cstddef>
52#include <cmath> 52#include <cmath>
… …
389// P. L'Ecuyer, “Maximally Equidistributed Combined Tausworthe Generators”, Mathematics of Computation, 65, 213 (1996), 203–213. 389// P. L'Ecuyer, “Maximally Equidistributed Combined Tausworthe Generators”, Mathematics of Computation, 65, 213 (1996), 203–213.
390// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps 390// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
391// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps 391// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
392struct tausworthe_random_generator 392struct tausworthe_random_generator
393{ 393{
394 // generator
395 uint32_t state [4]; 394 uint32_t state [4];
396 395
397 void operator =(const tausworthe_random_generator &src) 396 void operator =(const tausworthe_random_generator &src)
398 { 397 {
399 state [0] = src.state [0]; 398 state [0] = src.state [0];
… …
402 state [3] = src.state [3]; 401 state [3] = src.state [3];
403 } 402 }
404 403
405 void seed (uint32_t seed); 404 void seed (uint32_t seed);
406 uint32_t next (); 405 uint32_t next ();
406};
407 407
408// Xorshift RNGs, George Marsaglia
409// http://www.jstatsoft.org/v08/i14/paper
410// this one is about 40% faster than the tausworthe one above (i.e. not much),
411// despite the inlining, and has the issue of only creating 2**32-1 numbers.
412struct xorshift_random_generator
413{
414 uint32_t x, y;
415
416 void operator =(const xorshift_random_generator &src)
417 {
418 x = src.x;
419 y = src.y;
420 }
421
422 void seed (uint32_t seed)
423 {
424 x = seed;
425 y = seed * 69069U;
426 }
427
428 uint32_t next ()
429 {
430 uint32_t t = x ^ (x << 10);
431 x = y;
432 y = y ^ (y >> 13) ^ t ^ (t >> 10);
433 return y;
434 }
435};
436
437template<class generator>
438struct random_number_generator : generator
439{
408 // uniform distribution, 0 .. max (0, num - 1) 440 // uniform distribution, 0 .. max (0, num - 1)
409 uint32_t operator ()(uint32_t num) 441 uint32_t operator ()(uint32_t num)
410 { 442 {
411 return is_constant (num) 443 return !is_constant (num) ? get_range (num) // non-constant
412 ? (next () * (uint64_t)num) >> 32U 444 : num & (num - 1) ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two
413 : get_range (num); 445 : this->next () & (num - 1); // constant, power-of-two
414 } 446 }
415 447
416 // return a number within (min .. max) 448 // return a number within (min .. max)
417 int operator () (int r_min, int r_max) 449 int operator () (int r_min, int r_max)
418 { 450 {
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429protected: 461protected:
430 uint32_t get_range (uint32_t r_max); 462 uint32_t get_range (uint32_t r_max);
431 int get_range (int r_min, int r_max); 463 int get_range (int r_min, int r_max);
432}; 464};
433 465
434typedef tausworthe_random_generator rand_gen; 466typedef random_number_generator<tausworthe_random_generator> rand_gen;
435 467
436extern rand_gen rndm, rmg_rndm; 468extern rand_gen rndm, rmg_rndm;
437 469
438INTERFACE_CLASS (attachable) 470INTERFACE_CLASS (attachable)
439struct refcnt_base 471struct refcnt_base
… …
508 540
509struct str_hash 541struct str_hash
510{ 542{
511 std::size_t operator ()(const char *s) const 543 std::size_t operator ()(const char *s) const
512 { 544 {
513 unsigned long hash = 0; 545#if 0
546 uint32_t hash = 0;
514 547
515 /* use the one-at-a-time hash function, which supposedly is 548 /* use the one-at-a-time hash function, which supposedly is
516 * better than the djb2-like one used by perl5.005, but 549 * better than the djb2-like one used by perl5.005, but
517 * certainly is better then the bug used here before. 550 * certainly is better then the bug used here before.
518 * see http://burtleburtle.net/bob/hash/doobs.html 551 * see http://burtleburtle.net/bob/hash/doobs.html
… …
525 } 558 }
526 559
527 hash += hash << 3; 560 hash += hash << 3;
528 hash ^= hash >> 11; 561 hash ^= hash >> 11;
529 hash += hash << 15; 562 hash += hash << 15;
563#else
564 // use FNV-1a hash (http://isthe.com/chongo/tech/comp/fnv/)
565 // it is about twice as fast as the one-at-a-time one,
566 // with good distribution.
567 // FNV-1a is faster on many cpus because the multiplication
568 // runs concurrent with the looping logic.
569 uint32_t hash = 2166136261;
570
571 while (*s)
572 hash = (hash ^ *s++) * 16777619;
573#endif
530 574
531 return hash; 575 return hash;
532 } 576 }
533}; 577};
534 578

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