/******************************************************************************/ #ifdef JEMALLOC_H_TYPES /* * Simple linear congruential pseudo-random number generator: * * prng(y) = (a*x + c) % m * * where the following constants ensure maximal period: * * a == Odd number (relatively prime to 2^n), and (a-1) is a multiple of 4. * c == Odd number (relatively prime to 2^n). * m == 2^32 * * See Knuth's TAOCP 3rd Ed., Vol. 2, pg. 17 for details on these constraints. * * This choice of m has the disadvantage that the quality of the bits is * proportional to bit position. For example. the lowest bit has a cycle of 2, * the next has a cycle of 4, etc. For this reason, we prefer to use the upper * bits. * * Macro parameters: * uint32_t r : Result. * unsigned lg_range : (0..32], number of least significant bits to return. * uint32_t state : Seed value. * const uint32_t a, c : See above discussion. */ #define prng32(r, lg_range, state, a, c) do { \ assert(lg_range > 0); \ assert(lg_range <= 32); \ \ r = (state * (a)) + (c); \ state = r; \ r >>= (32 - lg_range); \ } while (false) /* Same as prng32(), but 64 bits of pseudo-randomness, using uint64_t. */ #define prng64(r, lg_range, state, a, c) do { \ assert(lg_range > 0); \ assert(lg_range <= 64); \ \ r = (state * (a)) + (c); \ state = r; \ r >>= (64 - lg_range); \ } while (false) #endif /* JEMALLOC_H_TYPES */ /******************************************************************************/ #ifdef JEMALLOC_H_STRUCTS #endif /* JEMALLOC_H_STRUCTS */ /******************************************************************************/ #ifdef JEMALLOC_H_EXTERNS #endif /* JEMALLOC_H_EXTERNS */ /******************************************************************************/ #ifdef JEMALLOC_H_INLINES #endif /* JEMALLOC_H_INLINES */ /******************************************************************************/