| 445 | } |
| 446 | |
| 447 | unsigned long rk_interval(unsigned long max, rk_state *state) { |
| 448 | unsigned long mask = max, value; |
| 449 | |
| 450 | if (max == 0) { |
| 451 | return 0; |
| 452 | } |
| 453 | /* Smallest bit mask >= max */ |
| 454 | mask |= mask >> 1; |
| 455 | mask |= mask >> 2; |
| 456 | mask |= mask >> 4; |
| 457 | mask |= mask >> 8; |
| 458 | mask |= mask >> 16; |
| 459 | #if ULONG_MAX > 0xffffffffUL |
| 460 | mask |= mask >> 32; |
| 461 | #endif |
| 462 | |
| 463 | /* Search a random value in [0..mask] <= max */ |
| 464 | #if ULONG_MAX > 0xffffffffUL |
| 465 | if (max <= 0xffffffffUL) { |
| 466 | while ((value = (rk_random(state) & mask)) > max) |
| 467 | ; |
| 468 | } else { |
| 469 | while ((value = (rk_ulong(state) & mask)) > max) |
| 470 | ; |
| 471 | } |
| 472 | #else |
| 473 | while ((value = (rk_ulong(state) & mask)) > max) |
| 474 | ; |
| 475 | #endif |
| 476 | return value; |
| 477 | } |
| 478 | |
| 479 | double rk_double(rk_state *state) { |
| 480 | /* shifts : 67108864 = 0x4000000, 9007199254740992 = 0x20000000000000 */ |