解释简单的代码?能详细点么?我太菜,什么位运算都给我弄孟了

function  reduce(arrayTime:array of integer):Integer;
var
  IntDate:Integer;
begin
  //IntDate:=0;
  IntDate:=arrayTime[0]-2000;
  IntDate:=IntDate Shl 4;
  IntDate:=IntDate+arrayTime[1];
  IntDate:=IntDate Shl 5;
  IntDate:=IntDate+arrayTime[2];
  IntDate:=IntDate Shl 5;
  IntDate:=IntDate+arrayTime[3];
  IntDate:=IntDate Shl 6;
  IntDate:=IntDate+arrayTime[4];
  IntDate:=IntDate shl 6;
  IntDate:=IntDate+arrayTime[5];
  Result:=IntDate;
end;procedure ecode(IntDate:Integer;var pTemp:array of integer);
begin
  pTemp[5]:=IntDate and 63;
  IntDate:=IntDate Shr 6;
  pTemp[4]:=IntDate and 63;
  IntDate:=IntDate Shr 6;
  pTemp[3]:=IntDate and 31;
  IntDate:=IntDate Shr 5;
  pTemp[2]:=IntDate and 31;
  IntDate:=IntDate Shr 5;
  pTemp[1]:=IntDate and 15;
  IntDate:=IntDate Shr 4;
  pTemp[0]:=(IntDate and 63)+2000;
end;