unix의 drand48()와 srand48() windows에서 사용하기

Unix                              ->        windows

srand48( (long)time(NULL) );    ->        srand((long)time(NULL));
drand48();                              ->        double(rand())/RAND_MAX;

 

아래에  drand48();        ->        double(rand())/(RAND_MAX+1.0); 이 맞는 거 같다는 말도 있는데 일단 급하니 쓰고봐야겠다...

 

링크 : https://social.msdn.microsoft.com/Forums/vstudio/en-US/9356f151-51d2-412d-8889-d53230cc6ec9/porting-srand48-and-drand48-of-unix-like-platform-based-source?forum=vclanguage

 

 

아래는 github에서 rand48과 srand48을 opensource로 공개한 소스이다.

링크 : https://gist.github.com/mortennobel/8665258

#define RAND48_SEED_0   (0x330e)
#define RAND48_SEED_1 (0xabcd)
#define RAND48_SEED_2 (0x1234)
#define RAND48_MULT_0 (0xe66d)
#define RAND48_MULT_1 (0xdeec)
#define RAND48_MULT_2 (0x0005)
#define RAND48_ADD (0x000b)
 
unsigned short _rand48_seed[3] = {
        RAND48_SEED_0,
         RAND48_SEED_1,
         RAND48_SEED_2
};
 
unsigned short _rand48_mult[3] = {
         RAND48_MULT_0,
         RAND48_MULT_1,
         RAND48_MULT_2
 };
 
unsigned short _rand48_add = RAND48_ADD;
 
void _dorand48(unsigned short xseed[3])
{
             unsigned long accu;
             unsigned short temp[2];
 
             accu = (unsigned long)_rand48_mult[0] * (unsigned long)xseed[0] +
              (unsigned long)_rand48_add;
             temp[0] = (unsigned short)accu;        /* lower 16 bits */
             accu >>= sizeof(unsigned short)* 8;
             accu += (unsigned long)_rand48_mult[0] * (unsigned long)xseed[1] +
              (unsigned long)_rand48_mult[1] * (unsigned long)xseed[0];
             temp[1] = (unsigned short)accu;        /* middle 16 bits */
             accu >>= sizeof(unsigned short)* 8;
             accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0];
             xseed[0] = temp[0];
             xseed[1] = temp[1];
             xseed[2] = (unsigned short)accu;
}
 
double erand48(unsigned short xseed[3])
{
         _dorand48(xseed);
         return ldexp((double) xseed[0], -48) +
                ldexp((double) xseed[1], -32) +
                ldexp((double) xseed[2], -16);
}
 
double drand48(){
    return erand48(_rand48_seed);
}
 
void srand48(long seed){
    _rand48_seed[0] = RAND48_SEED_0;
    _rand48_seed[1] = (unsigned short)seed;
    _rand48_seed[2] = (unsigned short)(seed >> 16);
    _rand48_mult[0] = RAND48_MULT_0;
    _rand48_mult[1] = RAND48_MULT_1;
    _rand48_mult[2] = RAND48_MULT_2;
    _rand48_add = RAND48_ADD;
}