with Interfaces.C.Strings; use Interfaces.C.Strings;
with System; use System;
with Unchecked_Conversion;
package body Interfaces.C.Pointers is
type Addr is mod Memory_Size;
function To_Pointer is new Unchecked_Conversion (Addr, Pointer);
function To_Addr is new Unchecked_Conversion (Pointer, Addr);
function To_Addr is new Unchecked_Conversion (ptrdiff_t, Addr);
function To_Ptrdiff is new Unchecked_Conversion (Addr, ptrdiff_t);
Elmt_Size : constant ptrdiff_t :=
(Element_Array'Component_Size
+ Storage_Unit - 1) / Storage_Unit;
subtype Index_Base is Index'Base;
function "+" (Left : Pointer; Right : ptrdiff_t) return Pointer is
begin
if Left = null then
raise Pointer_Error;
end if;
return To_Pointer (To_Addr (Left) + To_Addr (Elmt_Size * Right));
end "+";
function "+" (Left : ptrdiff_t; Right : Pointer) return Pointer is
begin
if Right = null then
raise Pointer_Error;
end if;
return To_Pointer (To_Addr (Elmt_Size * Left) + To_Addr (Right));
end "+";
function "-" (Left : Pointer; Right : ptrdiff_t) return Pointer is
begin
if Left = null then
raise Pointer_Error;
end if;
return To_Pointer (To_Addr (Left) - To_Addr (Right * Elmt_Size));
end "-";
function "-" (Left : Pointer; Right : Pointer) return ptrdiff_t is
begin
if Left = null or else Right = null then
raise Pointer_Error;
end if;
return To_Ptrdiff (To_Addr (Left) - To_Addr (Right)) / Elmt_Size;
end "-";
procedure Copy_Array
(Source : Pointer;
Target : Pointer;
Length : ptrdiff_t)
is
T : Pointer := Target;
S : Pointer := Source;
begin
if S = null or else T = null then
raise Dereference_Error;
else
for J in 1 .. Length loop
T.all := S.all;
Increment (T);
Increment (S);
end loop;
end if;
end Copy_Array;
procedure Copy_Terminated_Array
(Source : Pointer;
Target : Pointer;
Limit : ptrdiff_t := ptrdiff_t'Last;
Terminator : Element := Default_Terminator)
is
S : Pointer := Source;
T : Pointer := Target;
L : ptrdiff_t := Limit;
begin
if S = null or else T = null then
raise Dereference_Error;
else
while L > 0 loop
T.all := S.all;
exit when T.all = Terminator;
Increment (T);
Increment (S);
L := L - 1;
end loop;
end if;
end Copy_Terminated_Array;
procedure Decrement (Ref : in out Pointer) is
begin
Ref := Ref - 1;
end Decrement;
procedure Increment (Ref : in out Pointer) is
begin
Ref := Ref + 1;
end Increment;
function Value
(Ref : Pointer;
Terminator : Element := Default_Terminator) return Element_Array
is
P : Pointer;
L : constant Index_Base := Index'First;
H : Index_Base;
begin
if Ref = null then
raise Dereference_Error;
else
H := L;
P := Ref;
loop
exit when P.all = Terminator;
H := Index_Base'Succ (H);
Increment (P);
end loop;
declare
subtype A is Element_Array (L .. H);
type PA is access A;
function To_PA is new Unchecked_Conversion (Pointer, PA);
begin
return To_PA (Ref).all;
end;
end if;
end Value;
function Value
(Ref : Pointer;
Length : ptrdiff_t) return Element_Array
is
L : Index_Base;
H : Index_Base;
begin
if Ref = null then
raise Dereference_Error;
elsif Length <= 0 then
declare
pragma Warnings (Off); X : Element_Array (Index'Succ (Index'First) .. Index'First);
pragma Warnings (On);
begin
return X;
end;
else
L := Index'First;
H := Index'Val (Index'Pos (Index'First) + Length - 1);
declare
subtype A is Element_Array (L .. H);
type PA is access A;
function To_PA is new Unchecked_Conversion (Pointer, PA);
begin
return To_PA (Ref).all;
end;
end if;
end Value;
function Virtual_Length
(Ref : Pointer;
Terminator : Element := Default_Terminator) return ptrdiff_t
is
P : Pointer;
C : ptrdiff_t;
begin
if Ref = null then
raise Dereference_Error;
else
C := 0;
P := Ref;
while P.all /= Terminator loop
C := C + 1;
Increment (P);
end loop;
return C;
end if;
end Virtual_Length;
end Interfaces.C.Pointers;