add oversampler

oversampling/WDL/xsrand.h

@@ -0,0 +1,66 @@
+#ifndef _WDL_XSRAND_H_
+#define _WDL_XSRAND_H_
+
+#include "wdltypes.h"
+
+class XS64Rand {
+    WDL_UINT64 st;
+  public:
+    XS64Rand(WDL_UINT64 seed) { st=seed; if (!st) st++; }
+
+    WDL_UINT64 rand64()
+    {
+      WDL_UINT64 x=st;
+      x ^= x >> 12; // a
+      x ^= x << 25; // b
+      x ^= x >> 27; // c
+      return (st=x) * WDL_UINT64_CONST(2685821657736338717);
+    }
+
+    void add_entropy(WDL_UINT64 value) { st+=value; if (!st) st++; }
+};
+
+class XS1024Rand {
+     WDL_UINT64 st[16];
+     int p;
+
+  public:
+     XS1024Rand(WDL_UINT64 seed) : p(0)
+     {
+       memset(st,0x80,sizeof(st));
+       add_entropy(seed);
+     }
+     XS1024Rand(const void *buf, int bufsz) : p(0)
+     {
+       memset(st,0x80,sizeof(st));
+       add_entropy(buf,bufsz);
+     }
+
+     WDL_UINT64 rand64()
+     {
+       WDL_UINT64 s0 = st[ p ], *wr = st + (p = (p+1)&15), s1 = *wr;
+       s1 ^= s1 << 31; // a
+       s1 ^= s1 >> 11; // b
+       s0 ^= s0 >> 30; // c
+       return ( *wr = s0 ^ s1 ) * WDL_UINT64_CONST(1181783497276652981);
+     }
+
+     void add_entropy(WDL_UINT64 value)
+     {
+       XS64Rand r(value);
+       for (int x=0;x<16;x++) st[x]+=r.rand64();
+     }
+     void add_entropy(const void *buf, int bufsz)
+     {
+       unsigned char *wr = (unsigned char *)st;
+       if (bufsz > (int) sizeof(st)) bufsz = (int) sizeof(st);
+       if (buf)
+       {
+         const unsigned char *rd = (const unsigned char *)buf;
+         while (bufsz-->0) *wr++ += *rd++;
+       }
+     }
+};
+
+
+#endif