public static unsafe int POPCNTUnrolled2(ulong *bits, int bitLength, int offset)
{
long c1, c2, c3, c4;
c1 = c2 = c3 = c4 = 0;
if (HackersDelight.IsBitSet(bits, offset))
{
return(-1);
}
var index = 0L;
// Bits -> longs -> "complete" groups of 4 longs
var n = ((offset / 64) / 4) * 4;
for (var i = 0; i < n; i += 4, bits += 4)
{
c1 += PopCount(bits[0]);
c2 += PopCount(bits[1]);
c3 += PopCount(bits[2]);
c4 += PopCount(bits[3]);
}
index += c1 + c2 + c3 + c4;
offset -= n * 64;
while (offset >= 63)
{
index += PopCount(*(bits++));
offset -= 64;
}
return((int)(index + PopCount(*bits & ((1UL << (offset + 1)) - 1))));
}
public static unsafe int POPCNTUnrolled(ulong *bits, int bitLength, int offset)
{
if (HackersDelight.IsBitSet(bits, offset))
{
return(-1);
}
var index = 0L;
// Bits -> longs -> "complete" groups of 4 longs
var n = ((offset / 64) / 4) * 4;
for (var i = 0; i < n; i += 4, bits += 4)
{
//IACA_START
index += PopCount(bits[0]) + PopCount(bits[1]) + PopCount(bits[2]) + PopCount(bits[3]);
}
//IACA_END
offset -= n * 64;
//bits += n;
while (offset >= 63)
{
index += PopCount(*(bits++));
offset -= 64;
}
return((int)(offset >= 0 ? index + PopCount(*bits & ((1UL << (offset + 1)) - 1)) : index));
}
public static unsafe int NoIntrinsics(ulong *bits, int numBits, int offset)
{
if (HackersDelight.IsBitSet(bits, offset))
{
return(-1);
}
var index = 0;
while (offset >= 63)
{
//IACA_START
index += HackersDelight.PopCount(*(bits++));
offset -= 64;
}
//IACA_END
return(offset >= 0 ? index + HackersDelight.PopCount(*bits & ((1UL << (offset + 1)) - 1)) : index);
}
