Работа с деком на основе статических массивов

type
  deque = record
    data: array[1..MAXSIZE] of integer;
    head, tail: integer;
  end;
 
procedure push_front(var d: deque; x: integer);
begin
  if d.head < 1 then d.head += maxsize;
  d.data[(d.head - 1) mod maxsize] := x;
end;
 
procedure push_back(var d: deque; c: integer);
begin
  d.data[(d.tail + 1) mod maxsize] := x;
end;
 
function pop_front(var d: deque): integer;
begin
  result := d.data[(d.head + 1) mod maxsize];
end;
 
function pop_back(var d: deque): integer;
begin
  if d.head < 1 then d.tail += maxsize;
  result := d.data[(d.head - 1) mod maxsize];
end;

type TData = Integer;
function  deqLength(const q: array of TData; h, t: Integer): Integer;
begin
  h:=t-h; if h<0 then Inc(h,High(q)+1); deqLength:=h;
end;
procedure deqClear(const q: array of TData; var h, t: Integer);
begin
  h:=0; t:=0;
end;
procedure deqPushBack(const x: TData; var q: array of TData; var h, t: Integer);
begin
  q[t]:=x; Inc(t); if t>High(q) then Dec(t,High(q)+1);
end;
procedure deqPushFront(x: TData; var q: array of TData; var h, t: Integer);
begin
  Dec(h); if h<0 then Inc(h,High(q)+1); q[h]:=x;
end;
procedure deqPopBack(var x: TData; const q: array of TData; var h, t: Integer);
begin
  Dec(t); if t<0 then Inc(t,High(q)+1); x:=q[t];
end;
procedure deqPopFront(var x: TData; const q: array of TData; var h, t: Integer);
begin
  x:=q[h]; Inc(h); if h>High(q) then Dec(h,High(q)+1);
end;
var
  h, t: Integer;
  q: array [0..99] of TData;
  x: TData;
begin
  for x:=1 to 10 do deqPushBack(x,q,h,t);
  WriteLn(deqLength(q,h,t));
  while h<>t do begin
    deqPopFront(x,q,h,t); Write(' ',x);
  end; WriteLn;
end.