// [Bat 68] K.E. Batcher: Sorting Networks and their Applications. Proc. AFIPS Spring Joint Comput. Conf., Vol. 32, 307-314 (1968)
// Work inefficient sort, because half the threads are unused.
public static void SeqBitonicSort1(int[] a)
{
uint N = (uint)a.Length;
int term = Bithacks.FloorLog2(N);
for (int kk = 2; kk <= N; kk *= 2)
{
for (int jj = kk >> 1; jj > 0; jj = jj >> 1)
{
int k = kk;
int j = jj;
for (int i = 0; i < N; ++i)
{
int ij = i ^ j;
if (ij > i)
{
if ((i & k) == 0)
{
if (a[i] > a[ij])
{
swap(ref a[i], ref a[ij]);
}
}
else // ((i & k) != 0)
{
if (a[i] < a[ij])
{
swap(ref a[i], ref a[ij]);
}
}
}
}
}
}
}
public static int xFloorLog2(uint x)
{
x |= (x >> 1);
x |= (x >> 2);
x |= (x >> 4);
x |= (x >> 8);
x |= (x >> 16);
return(Bithacks.Ones(x) - 1);
}
public static int CeilingLog2(uint v)
{
int r = Bithacks.FloorLog2(v);
if (r < 0)
{
return(r);
}
if (v != (uint)Bithacks.Power2((uint)r))
{
return(r + 1);
}
else
{
return(r);
}
}
public static void BitonicSort2(int[] a)
{
Parallel.Sticky(a);
uint N = (uint)a.Length;
int log2n = Bithacks.FloorLog2(N);
for (int k = 0; k < log2n; ++k)
{
uint n2 = N / 2;
int twok = Bithacks.Power2(k);
Campy.Parallel.For((int)n2, i =>
{
int imp2 = i % twok;
int cross = imp2 + 2 * twok * (int)(i / twok);
int paired = -1 - imp2 + 2 * twok * (int)((i + twok) / twok);
if (a[cross] > a[paired])
{
int t = a[cross];
a[cross] = a[paired];
a[paired] = t;
}
});
for (int j = k - 1; j >= 0; --j)
{
int twoj = Bithacks.Power2(j);
Campy.Parallel.For((int)n2, i =>
{
int imp2 = i % twoj;
int cross = imp2 + 2 * twoj * (int)(i / twoj);
int paired = cross + twoj;
if (a[cross] > a[paired])
{
int t = a[cross];
a[cross] = a[paired];
a[paired] = t;
}
});
}
}
Parallel.Sync();
}
public static void SeqBitonicSort2(int[] a)
{
uint N = (uint)a.Length;
int log2n = Bithacks.FloorLog2(N);
for (int k = 0; k < log2n; ++k)
{
uint n2 = N / 2;
int twok = Bithacks.Power2(k);
for (int i = 0; i < n2; ++i)
{
int imp2 = i % twok;
int cross = imp2 + 2 * twok * (int)(i / twok);
int paired = -1 - imp2 + 2 * twok * (int)((i + twok) / twok);
if (a[cross] > a[paired])
{
int t = a[cross];
a[cross] = a[paired];
a[paired] = t;
}
}
for (int j = k - 1; j >= 0; --j)
{
int twoj = Bithacks.Power2(j);
for (int i = 0; i < n2; ++i)
{
int imp2 = i % twoj;
int cross = imp2 + 2 * twoj * (int)(i / twoj);
int paired = cross + twoj;
if (a[cross] > a[paired])
{
int t = a[cross];
a[cross] = a[paired];
a[paired] = t;
}
}
}
}
}
public static void BitonicSort1(int[] a)
{
Parallel.Sticky(a);
uint N = (uint)a.Length;
int term = Bithacks.FloorLog2(N);
for (int kk = 2; kk <= N; kk *= 2)
{
for (int jj = kk >> 1; jj > 0; jj = jj >> 1)
{
int k = kk;
int j = jj;
Campy.Parallel.For((int)N, (i) =>
{
int ij = i ^ j;
if (ij > i)
{
if ((i & k) == 0)
{
if (a[i] > a[ij])
{
swap(ref a[i], ref a[ij]);
}
}
else // ((i & k) != 0)
{
if (a[i] < a[ij])
{
swap(ref a[i], ref a[ij]);
}
}
}
});
}
}
Parallel.Sync();
}
