好的 C 随机数生成器
我想将 CMWC4096 代码移植到 Java,但它使用多个无符号数据类型,因此我不确定如何正确地进行操作。这是完整的 C 代码:
/* choose random initial c<809430660 and */
/* 4096 random 32-bit integers for Q[] */
static unsigned long Q[4096],c=362436;
unsigned long CMWC4096(void) {
unsigned long long t, a=18782LL;
static unsigned long i=4095;
unsigned long x,r=0xfffffffe;
i = (i+1) & 4095;
t = a*Q[i] + c;
c = (t>>32);
x = t + c;
if (x < c) {
x++;
c++;
}
return (Q[i] = r - x);
}
有人能将这个移植到Java吗?当你只有有符号数可用时,这个怎么工作呢?
编辑:感谢大家的快速回答!对于前1亿个数字,这段Java代码似乎产生了与C代码相同的结果。它比Java的java.util.Random快3倍。
public class ComplimentaryMultiplyWithCarryRandom {
/**
* Choose 4096 random 32-bit integers
*/
private long[] Q;
/**
* choose random initial c<809430660
*/
private long c = 362436;
private int i;
public ComplimentaryMultiplyWithCarryRandom() {
Random r = new Random(1);
Q = new long[4096];
// TODO initialize with real random 32bit values
for (int i = 0; i < 4096; ++i) {
long v = r.nextInt();
v -= Integer.MIN_VALUE;
Q[i] = v;
}
i = 4095;
}
int next() {
i = (i + 1) & 4095;
long t = 18782 * Q[i] + c;
c = t >>> 32;
long x = (t + c) & 0xffffffffL;
if (x < c) {
++x;
++c;
}
long v = 0xfffffffeL - x;
Q[i] = v;
return (int) v;
}
}