private static ulong ExtractUInt64_Hybrid1(ReadOnlySpan <byte> span, int bitOffset)
{
int ix = bitOffset >> 3; // div 8
var len = Math.Max(0, span.Length - ix);
int shft = bitOffset & 7; // mod 8
var blit = new Blit64();
ulong val = 0;
switch (len)
{
case 0: throw new ArgumentOutOfRangeException(nameof(bitOffset));
// Need at least 8+1 bytes
default:
val = (ulong)span[ix + 8] << (64 - shft);
goto case 8;
case 8: blit.u64 = MemoryMarshal.Cast <byte, ulong>(span.Slice(ix, 8))[0]; break;
case 7: blit.b6 = span[ix + 6]; goto case 6;
case 6: blit.b5 = span[ix + 5]; goto case 5;
case 5: blit.b4 = span[ix + 4]; goto case 4;
case 4: blit.i0 = MemoryMarshal.Cast <byte, uint>(span.Slice(ix, 4))[0]; break;
case 3: blit.b2 = span[ix + 2]; goto case 2;
case 2: blit.s0 = MemoryMarshal.Cast <byte, ushort>(span.Slice(ix, 2))[0]; break;
case 1: blit.b0 = span[ix + 0]; break;
}
val |= blit.u64 >> shft;
return(val);
}
private static ulong ExtractUInt64_Blit(ReadOnlySpan <byte> span, int bitOffset)
{
int ix = bitOffset >> 3; // div 8
var len = Math.Max(0, span.Length - ix);
int shft = bitOffset & 7; // mod 8
var blit = new Blit64();
ulong val = 0;
switch (len)
{
case 0: throw new ArgumentOutOfRangeException(nameof(bitOffset));
// Need at least 8+1 bytes
default:
val = (ulong)span[ix + 8] << (64 - shft);
goto case 8;
case 8: blit.b7 = span[ix + 7]; goto case 7;
case 7: blit.b6 = span[ix + 6]; goto case 6;
case 6: blit.b5 = span[ix + 5]; goto case 5;
case 5: blit.b4 = span[ix + 4]; goto case 4;
case 4: blit.b3 = span[ix + 3]; goto case 3;
case 3: blit.b2 = span[ix + 2]; goto case 2;
case 2: blit.b1 = span[ix + 1]; goto case 1;
case 1: blit.b0 = span[ix + 0]; break;
}
val |= blit.u64 >> shft;
return(val);
}
