__int64 __fastcall RawComputeFileSystemInformationChecksum(__int64 a1){
unsigned __int16 v1;
unsigned __int16 i;
v1 = 0;
for( i = 3; i < *(_WORD *)(a1 + 20); ++i )
{
if( (unsigned __int16)(i - 22) > 1u )
v1 = (v1 << 15) + *(unsigned __int8 *)(i + a1) + (v1 >> 1);
}
return v1;
}