HexPosition?FindCore(SearchState state, HexPosition start, HexPosition upperBounds)
{
var patternLocal = pattern;
var maskLocal = mask;
var pos = start;
if (pos + patternLocal.LongLength > upperBounds)
{
return(null);
}
var endPos = upperBounds - patternLocal.LongLength + 1;
state.SetPosition(pos);
var patternLocal0 = patternLocal[0];
var maskLocal0 = maskLocal[0];
var patternLocal1 = patternLocal.Length <= 1 ? 0 : patternLocal[1];
var maskLocal1 = maskLocal.Length <= 1 ? 0 : maskLocal[1];
var maskLocalLengthIsAtLeast2 = maskLocal.Length >= 2;
loop:
// This loop doesn't check the cancellation token because SearchState does that
// every time it reads new memory from the buffer.
if (pos >= endPos)
{
return(null);
}
int skip;
HexPosition?afterPos;
if (maskLocalLengthIsAtLeast2)
{
skip = 2;
afterPos = maskLocal0 == 0xFF ?
state.PositionAfter2(patternLocal0, patternLocal1, maskLocal1, endPos) :
state.PositionAfterWithMask2(patternLocal0, patternLocal1, maskLocal0, maskLocal1, endPos);
}
else if (maskLocal0 == 0xFF)
{
skip = 1;
afterPos = state.PositionAfter1(patternLocal0, endPos);
}
else
{
skip = 1;
afterPos = state.PositionAfterWithMask1(patternLocal0, maskLocal0, endPos);
}
if (afterPos == null)
{
return(null);
}
pos = afterPos.Value;
for (int i = skip; i < patternLocal.Length; i++)
{
var b = state.GetNextByte();
var m = maskLocal[i];
if ((b & m) != patternLocal[i])
{
pos = pos - (skip - 1);
state.SetPosition(pos);
goto loop;
}
}
return(pos - skip);
}