WDL/xsrand.h

   1 #ifndef _WDL_XSRAND_H_
   2 #define _WDL_XSRAND_H_
   3
   4 #include "wdltypes.h"
   5
   6 class XS64Rand {
   7     WDL_UINT64 st;
   8   public:
   9     XS64Rand(WDL_UINT64 seed) { st=seed; if (!st) st++; }
  10
  11     WDL_UINT64 rand64()
  12     {
  13       WDL_UINT64 x=st;
  14       x ^= x >> 12; // a
  15       x ^= x << 25; // b
  16       x ^= x >> 27; // c
  17       return (st=x) * WDL_UINT64_CONST(2685821657736338717);
  18     }
  19
  20     void add_entropy(WDL_UINT64 value) { st+=value; if (!st) st++; }
  21 };
  22
  23 class XS1024Rand {
  24      WDL_UINT64 st[16];
  25      int p;
  26
  27   public:
  28      XS1024Rand(WDL_UINT64 seed) : p(0)
  29      {
  30        memset(st,0x80,sizeof(st));
  31        add_entropy(seed);
  32      }
  33      XS1024Rand(const void *buf, int bufsz) : p(0)
  34      {
  35        memset(st,0x80,sizeof(st));
  36        add_entropy(buf,bufsz);
  37      }
  38
  39      WDL_UINT64 rand64()
  40      {
  41        WDL_UINT64 s0 = st[ p ], *wr = st + (p = (p+1)&15), s1 = *wr;
  42        s1 ^= s1 << 31; // a
  43        s1 ^= s1 >> 11; // b
  44        s0 ^= s0 >> 30; // c
  45        return ( *wr = s0 ^ s1 ) * WDL_UINT64_CONST(1181783497276652981);
  46      }
  47
  48      void add_entropy(WDL_UINT64 value)
  49      {
  50        XS64Rand r(value);
  51        for (int x=0;x<16;x++) st[x]+=r.rand64();
  52      }
  53      void add_entropy(const void *buf, int bufsz)
  54      {
  55        unsigned char *wr = (unsigned char *)st;
  56        if (bufsz > (int) sizeof(st)) bufsz = (int) sizeof(st);
  57        if (buf)
  58        {
  59          const unsigned char *p = (const unsigned char *)buf;
  60          while (bufsz-->0) *wr++ += *p++;
  61        }
  62      }
  63 };
  64
  65
  66 #endif