Logo Search packages:      
Sourcecode: ksh version File versions  Download package

rand48.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#include "FEATURE/uwin"

#if !_UWIN || _lib_srand48

void _STUB_srand48(){}

#else

#define drand48   ______drand48
#define erand48   ______erand48
#define jrand48   ______jrand48
#define lcong48   ______lcong48
#define lrand48   ______lrand48
#define mrand48   ______mrand48
#define nrand48   ______nrand48
#define seed48    ______seed48
#define srand48   ______srand48

#include    <stdlib.h>

#undef      drand48
#undef      erand48
#undef      jrand48
#undef      lcong48
#undef      lrand48
#undef      mrand48
#undef      nrand48
#undef      seed48
#undef      srand48

#if defined(__EXPORT__)
#define extern          __EXPORT__
#endif

#define A   0x5DEECE66D
#define A0  0X5
#define A1  0xDEEC
#define A2  0xE66D
#define C   0xB
#define XINIT     0x330E
#define SCALE     3.55271e-15

static unsigned short oldval[3];
static unsigned short X[3] = { 0, 0, XINIT};
static unsigned short a[3] = { A0, A1, A2};
static unsigned short c = C;

static void multadd(unsigned short x[3], unsigned short a[3], unsigned short c)
{
      register unsigned long r = c;
      unsigned short x2 = x[2];
      unsigned short x1 = x[1];
      r += a[2]*x2;
      x[2] = (unsigned short)r;
      r >>= 16;
      r += a[1]*x2;
      r += a[2]*x1;
      x[1] = (unsigned short)r;
      r >>= 16;
      r += a[2]*x[0];
      r += a[1]*x1;
      r += a[0]*x2;
      x[0] = (unsigned short)r;
}

extern double drand48(void)
{
      double d;
      unsigned long u;
      multadd(X,a,c);
      u = (X[0]<<16) + X[1];
      d = (u*65536.) + X[2];
      return(d*SCALE);
}

extern double erand48(unsigned short xsubi[3])
{
      double d;
      unsigned long u;
      multadd(xsubi,a,c);
      u = (xsubi[0]<<16) + xsubi[1];
      d = (u*65536.) + xsubi[2];
      return(d*SCALE);
}

extern long jrand48(unsigned short xsubi[3])
{
      long u;
      multadd(xsubi,a,c);
      u = (xsubi[0]<<16) | xsubi[1];
      return((long)u);
}

extern void lcong48(unsigned short param[7])
{
      X[0] = param[0];
      X[1] = param[1];
      X[2] = param[2];
      a[0] = param[3];
      a[1] = param[4];
      a[2] = param[5];
      c = param[6];
}

extern long lrand48(void)
{
      long l;
      multadd(X,a,c);
      l = (X[0]<<15)|(X[1]>>1);
      return(l);
}

extern long mrand48(void)
{
      unsigned long u;
      multadd(X,a,c);
      u = (X[0]<<16) | X[1];
      return((long)u);
}

extern long nrand48(unsigned short xsubi[3])
{
      long l;
      multadd(xsubi,a,c);
      l = (xsubi[0]<<15)|(xsubi[1]>>1);
      return(l);
}

extern unsigned short *seed48(unsigned short seed[3])
{
      unsigned short *sp = (unsigned short*)&X;
      a[0] = A0;
      a[1] = A1;
      a[2] = A2;
      c = C;
      oldval[0] = X[2];
      oldval[1] = X[1];
      oldval[2] = X[0];
      X[0] = seed[2];
      X[1] = seed[1];
      X[2] = seed[0];
      return(oldval);
}

extern void srand48(long seedval)
{
      a[0] = A0;
      a[1] = A1;
      a[2] = A2;
      c = C;
      X[0] = (unsigned short)(((unsigned long)seedval) >> 16);
      X[1] = (unsigned short)seedval;
      X[2] = XINIT; 
}

#endif

Generated by  Doxygen 1.6.0   Back to index