| … | |
… | |
| 481 | }; |
481 | }; |
| 482 | |
482 | |
| 483 | template<class generator> |
483 | template<class generator> |
| 484 | struct random_number_generator : generator |
484 | struct random_number_generator : generator |
| 485 | { |
485 | { |
| 486 | // uniform distribution, 0 .. max (0, num - 1) |
486 | // uniform distribution, [0 .. num - 1] |
| 487 | uint32_t operator ()(uint32_t num) |
487 | uint32_t operator ()(uint32_t num) |
| 488 | { |
488 | { |
| 489 | return !is_constant (num) ? get_range (num) // non-constant |
489 | return !is_constant (num) ? get_range (num) // non-constant |
| 490 | : num & (num - 1) ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two |
490 | : num & (num - 1) ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two |
| 491 | : this->next () & (num - 1); // constant, power-of-two |
491 | : this->next () & (num - 1); // constant, power-of-two |
| … | |
… | |
| 497 | return is_constant (r_min <= r_max) && r_min <= r_max |
497 | return is_constant (r_min <= r_max) && r_min <= r_max |
| 498 | ? r_min + operator ()(r_max - r_min + 1) |
498 | ? r_min + operator ()(r_max - r_min + 1) |
| 499 | : get_range (r_min, r_max); |
499 | : get_range (r_min, r_max); |
| 500 | } |
500 | } |
| 501 | |
501 | |
| 502 | // return a number within the closed interval [0..1] |
502 | // return a number within the half-open interval [0..1[ |
| 503 | double operator ()() |
503 | double operator ()() |
| 504 | { |
504 | { |
| 505 | return this->next () / (double)0xFFFFFFFFU; |
505 | return this->next () / 0x100000000; |
| 506 | } |
506 | } |
| 507 | |
507 | |
| 508 | protected: |
508 | protected: |
| 509 | uint32_t get_range (uint32_t r_max); |
509 | uint32_t get_range (uint32_t r_max); |
| 510 | int get_range (int r_min, int r_max); |
510 | int get_range (int r_min, int r_max); |
