Ada error: invalid use of subtype mark in expression or call - ada

I'm stuck here with an error in my Ada program. There is a lot of code and I don't want to copy all of it here, so I hope that the part that I'm sharing is the part from where the problem comes.
task type Producent is
entry Start(Jedzenie: in Typ_Jedzenia; Czas_Produkcji: in Integer);
end Producent;
task type Buffer is
entry Zamow(Jedzenie: in Typ_Jedzenia; Numer: in Integer; Czy_Zatwierdzono: out Boolean);
entry Dostarcz(Zamowienie: in Typ_Zestawu; Numer: out Integer);
end Buffer;
task body Producent is
package Losowa_Produkcja is new
Ada.Numerics.Discrete_Random(Zakres_Czasu_Produkcji);
Generator: Losowa_Produkcja.Generator;
Index_Jedzenia: Integer;
Nr_Produkcji_Jedzenia: Integer := 1;
Produkcja: Integer;
Zatwierdzono: Boolean := False;
begin
accept Start (Jedzenie : in Typ_Jedzenia; Czas_Produkcji : in Integer) do
Losowa_Produkcja.Reset(Generator);
Index_Jedzenia := Jedzenie;
Produkcja := Czas_Produkcji;
end Start;
loop
delay Duration(Losowa_Produkcja.Random(Generator));
Put_Line("Przygotowano " & Nazwa_Jedzenia(Index_Jedzenia) & " numer " & Integer'Image(Nr_Produkcji_Jedzenia));
loop
Buffer.Zamow(Index_Jedzenia, Nr_Produkcji_Jedzenia, Zatwierdzono); <-------- ERROR
if Zatwierdzono = False then
Put_Line("Brak miejsca w kuchni dla " & Nazwa_Jedzenia(Index_Jedzenia) & ". Wstrzymanie");
delay Duration(3.0);
else
Nr_Produkcji_Jedzenia := Nr_Produkcji_Jedzenia + 1;
end if;
exit;
end loop;
end loop;
end Producent;
task body Buffer is
begin
Put_Line("Jestesmy u Buffera");
loop
select
accept Zamow(Jedzenie: in Typ_Jedzenia; Numer: in Integer; Czy_Zatwierdzono: out Boolean) do
Put_Line("Trwa zamawianie...");
end Zamow;
end select;
end loop;
end Buffer;
From my attempts I understand that when I want to call entry Buffer.Zamow(Index_Jedzenia, Nr_Produkcji_Jedzenia, Zatwierdzono); (which is in task Producent) there is an error with 'Zatwierdzono' argument. When I removed this argument from declarations and definitions Zamow() entry worked.
Full error: invalid use of subtype mark in expression or call
What should I change or where is the problem with this boolean Zatwierdzono variable?
Zatwierdzono means Accepted in this case.
Thanks for any ideas.

You have two problems:
Index_Jedzenia := Jedzenie;
In your Start entry is trying to implicitly convert Jedzenie from its type, Typ_Jedzenia, to Integer, the type of Index_Jedzenia. You need some way to convert this.
Additionally on the line you are seeing the error on, the first parameter of that entry is of type Typ_Jedzenia but you are passing in an Integer (Index_Jedzenia is an integer). Again, you can't implicitly convert types like that.
If Typ_Jedzenia is actually an integer, you can explicitly convert them. Otherwise you need to make a conversion function of some type and use that before passing in or assigning to different types.

Related

Function and procedure subprogram

I need to only use one function and one procedure and unfortunately I didn't manage to solve this problem.
The problem goes as following:
Create a subprogram that has three parameters. One string and two sign.
The subroutine must pick the first and last character in the string. The main program will then print these two characters.
Create a subprogram that retrieves a character, from the keyboard, which represents a truth value (see driving example).
The subprogram must send back the corresponding truth value to the main program.
In the terminal it should look like:
Type a string containing 6 characters: Overfl
First character is: O
Last character is : l
Type F or T (for False or True): T
You typed True
This is how my code looks like:
with Ada.Text_IO; use Ada.Text_IO;
procedure Test is
procedure String_Check(
S : in String;
Char_1, Char_2 : out Character
) is
begin
Char_1 := S(S'First);
Char_2 := S(S'Last);
end String_Check;
function Character_Check return Boolean is
Check : Integer;
begin
Put("Type F or T (For False or True): ");
Get(Check)
if Check = 'T' then
return True;
else
return False;
end if;
end Character_Check;
Char_1, Char_2 : Character;
Check : Character;
S : String(1 .. 6);
begin
Put("Type a string containing 6 characters: ");
Get(S);
String_Check(S, Char_1, Char_2);
Put("First character is: ");
Put(Char_1);
New_Line;
Put("Last character is: ");
Put(Char_2);
Skip_Line;
New_Line(2);
Put("You typed ");
if Character_Check then
Put("True");
else
Put("False");
end if;
end Test;
My code runs but it doesn't fulfill the given requirements. I guess I can't use a function in my second subprogram because the instruction says "create a subprogram that receives a character from the keyboard". How am I supposed to do Get in a function? But if I make my second program to a procedure I have to make my first program to a function. How am I supposed to do return for two values at the same time?

How do I enforce that a type hold only be a fixed set of non-contiguous values?

I was expecting this program to raise an error when I feed it 3 as a valid Scale value, but no such luck:
with Ada.Text_IO; use Ada.Text_IO;
procedure predicate is
type Scale is new Integer
with Dynamic_Predicate => Scale in 1 | 2 | 4 | 8;
GivesWarning : Scale := 3; -- gives warning
begin
Put_Line ("Hello World");
loop
Put_Line ("Gimme a value");
declare
AnyValue : Integer := Integer'Value (Get_Line);
S : Scale := Scale (AnyValue); -- no check done!
begin
Put_Line ("okay, that works" & S'Image);
end;
end loop;
end predicate;
I found this related question, but there the requirement is to use an enum., and the solution is to define an array from enum -> value.
I want something that gives me at least a warning at compile time, and allows me to check at runtime as well, and that raises an error if I try to put an invalid value in. Then, if I can use SPARK to prove that no invalid values can occur, I could turn off said checks. I was under the impression that this was how Static_ / Dynamic_ predicates work, so the example above took me by surprise.
You need to enable assertions. Either compile with -gnata or set an appropriate Assertion_Policy
pragma Assertion_Policy(Dynamic_Predicate => Check);

Interfacing Ada to C - getting Wide Strings from wchar_t *

I'm interfacing to a USB device (on Debian Stretch) using hidraw, and I need to process some information supplied by the USB device in the form of wchar_t* which I need to convert into (Ada) Wide_String. This is giving some trouble and I'm not seeing a clean way forward using the facilities in Interfaces.C and Interfaces.C.Strings.
All files are edited down without destroying their consistency. They will build, but without one of these, they won't actually run.
The problem is that device information like Serial Number and Product Name are presented by the Linux device driver as an access stddef_h.wchar_t from which I want to return a Wide_String or even a normal String) and I'm not seeing any good way to get there.
Interfaces.C.Strings has function Value (Item : in chars_ptr) return String; but no equivalent exists for Wide_String that I can see. So I think I need an equivalent Value function for wide characters.
The approach below uses To_Ada (from Interfaces.C) to return a Wide_String given a wchar_array. It fails, of course, because an access wchar_t is not convertible to a wchar_array.
-- helper function to deal with wchar_t * to wide_string
function Value (P : access stddef_h.wchar_t) return Wide_String is
temp : Wide_String(1 .. 256);
count : natural := 0;
-- ugliness to convert pointer types
type sd_wchar_ptr is access all stddef_h.wchar_t;
type wchar_array_ptr is access wchar_array;
Function To_Wchar_Array_Ptr is new Ada.Unchecked_Conversion(sd_wchar_ptr, wchar_array_ptr);
-- this does NOT create the required wchar_array pointer
WCP : wchar_array_ptr := To_Wchar_Array_Ptr(sd_wchar_ptr(P));
begin
Put_Line("Wide string");
To_Ada(WCP.all, temp, count);
Put_Line("Wide string length " & natural'image(count));
return temp(1..count);
end Value;
and the inevitable result
./test_hid
Wide string
Execution terminated by unhandled exception raised STORAGE_ERROR :
stack overflow or erroneous memory access
A similar character by character approach would be possible ... if (and I can't believe I'm saying this!) you could increment access types...
Feels like there's something missing from Interfaces.C here... what am I missing? any ideas to get round this relatively trivial seeming stumbling block?
EDIT : I'm leaning towards some brazen theft from the Interfaces.C.Strings sources with appropriate changes, but I'd welcome alternative suggestions.
The rest of this below is the full story so far (including all code necessary to reproduce)
Step 1 : generate low level Ada bindings automatically using gcc.
gcc -c -fdump-ada-spec-slim /usr/include/hidapi/hidapi.h
producing the low level binding package hidapi_hidapi_h
pragma Ada_2005;
pragma Style_Checks (Off);
with Interfaces.C; use Interfaces.C;
with Interfaces.C.Strings;
with stddef_h;
with System;
package hidapi_hidapi_h is
-- see source file /usr/include/hidapi/hidapi.h
type hid_device_info is record
path : Interfaces.C.Strings.chars_ptr; -- /usr/include/hidapi/hidapi.h:51
vendor_id : aliased unsigned_short; -- /usr/include/hidapi/hidapi.h:53
product_id : aliased unsigned_short; -- /usr/include/hidapi/hidapi.h:55
serial_number : access stddef_h.wchar_t; -- /usr/include/hidapi/hidapi.h:57
release_number : aliased unsigned_short; -- /usr/include/hidapi/hidapi.h:60
manufacturer_string : access stddef_h.wchar_t; -- /usr/include/hidapi/hidapi.h:62
product_string : access stddef_h.wchar_t; -- /usr/include/hidapi/hidapi.h:64
usage_page : aliased unsigned_short; -- /usr/include/hidapi/hidapi.h:67
usage : aliased unsigned_short; -- /usr/include/hidapi/hidapi.h:70
interface_number : aliased int; -- /usr/include/hidapi/hidapi.h:75
next : access hid_device_info; -- /usr/include/hidapi/hidapi.h:78
end record;
pragma Convention (C_Pass_By_Copy, hid_device_info); -- /usr/include/hidapi/hidapi.h:49
function hid_enumerate (arg1 : unsigned_short; arg2 : unsigned_short) return access hid_device_info; -- /usr/include/hidapi/hidapi.h:132
pragma Import (C, hid_enumerate, "hid_enumerate");
end hidapi_hidapi_h;
This is a low level binding, exposing C types (and the binding generator has decided that the wchar_t in Interfaces.C isn't good enough, it wants one from stddef.h too, so...
pragma Ada_2005;
pragma Style_Checks (Off);
with Interfaces.C; use Interfaces.C;
package stddef_h is
-- unsupported macro: NULL ((void *)0)
subtype size_t is unsigned_long; -- /usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:216
subtype wchar_t is int; -- /usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:328
end stddef_h;
Because it is a low level binding; we want to hide it (and implement RAII etc) behind a simpler and more usable high level binding, so ... (below)
with Ada.Finalization; use Ada.Finalization;
private with hidapi_hidapi_h;
private with System;
package hidapi is
type id is new natural range 0 .. 2**16 - 1;
type hid_device is new Limited_Controlled with private;
-- find first matching devices by enumeration : the RA part of RAII.
function enumerate (vendor_id, product_id : id) return hid_device;
-- accessors for device characteristics on enumerated device
function Serial_No (D : hid_device) return Wide_String;
function Product_String (D : hid_device) return Wide_String;
private
type hid_device is new Limited_Controlled with record
member : access hidapi_hidapi_h.hid_device_info;
addr : System.Address;
end record;
end hidapi;
and its implementation, containing the problem function value to return a Wide_String.
with hidapi_hidapi_h;
with Interfaces.C; use Interfaces.C;
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Unchecked_Conversion;
with stddef_h;
package body hidapi is
function enumerate (vendor_id, product_id : id) return hid_device is
use hidapi_hidapi_h;
first : access hid_device_info;
begin
first := hid_enumerate(unsigned_short(vendor_id), unsigned_short(product_id));
if first /= null then
return H : hid_device do
H.member := first;
H.addr := System.Null_Address;
end return;
else raise Program_Error;
end if;
end enumerate;
-- helper function to deal with wchar_t * to wide_string
function Value (P : access stddef_h.wchar_t) return Wide_String is
temp : Wide_String(1 .. 256);
count : natural := 0;
type sd_wchar_ptr is access all stddef_h.wchar_t;
type wchar_array_ptr is access wchar_array;
Function To_Wchar_Array_Ptr is new Ada.Unchecked_Conversion(sd_wchar_ptr, wchar_array_ptr);
WCP : wchar_array_ptr := To_Wchar_Array_Ptr(sd_wchar_ptr(P));
begin
Put_Line("Wide string");
To_Ada(WCP.all, temp, count);
Put_Line("Wide string length " & natural'image(count));
return temp(1..count);
end Value;
function Serial_No (D : hid_device) return Wide_String is
use hidapi_hidapi_h;
begin
return Value(D.member.serial_number);
end Serial_No;
function Product_String (D : hid_device) return Wide_String is
use hidapi_hidapi_h;
begin
return Value(D.member.product_string);
end Product_String;
end hidapi;
And of course a test case to exercise it...
with Hidapi;
with Ada.Wide_Text_IO;
procedure Test_Hid is
usbrelay_vendor_id : constant Hidapi.id := 16#16c0#;
usbrelay_product_id : constant Hidapi.id := 16#05df#;
Device : Hidapi.hid_device := Hidapi.Enumerate(usbrelay_vendor_id, usbrelay_product_id);
begin
Ada.Wide_Text_IO.Put_Line("Serial : " & Device.Serial_No);
Ada.Wide_Text_IO.Put_Line("Product : " & Device.Product_String);
end Test_Hid;
One answer, slavishly copying the approach in the package body for Tnterfaces.C.Strings with necessary changes.
The naughty stuff is in functions "+" and Peek which use Unchecked Conversions on pointers,
to permit address arithmetic. Not pointer increment, but pointer+offset. One change is that the offset has to be scaled for 4 byte characters. I haven't set that scaling in a portable manner, but note that "+" will overload for each different return type so that offsets will be scaled appropriately for different named access types.
to allow the stddef_h.wchar_t to be viewed as a Wide_Wide_Character in the absence of any type conversion function. Whether the representation is correct is another matter (here, it is) but this technique could also be used to fake the input type of a suitable conversion function like To_Ada in Interfaces.C.
The remainder is straightforward character by character handling. One other change (so far) is to return Wide_Wide_Character rather than Wide_Character (because as the stddef_h package above reveals, the stored characters are 32 bit, same size as Interfaces.C.int. I'm happy to change my interface, but Wide_String could be easily handled by Ada.Strings packages.
type sd_wchar_ptr is access all stddef_h.wchar_t;
type w_w_char_ptr is access all char32_t;
-- Two Unchecked_Conversions to allow pointer arithmetic
-- And a third to allow the resulting storage to be interpreted as Wide_Wide_Char
function To_Sd_wchar_ptr is new Ada.Unchecked_Conversion (System.Address, sd_wchar_ptr);
function To_Address is new Ada.Unchecked_Conversion (sd_wchar_ptr, System.Address);
function To_Wchar_Ptr is new Ada.Unchecked_Conversion (sd_wchar_ptr, w_w_char_ptr);
-- pointer + offset arithmetic, with offset scaled for size of stddef_h.wchar_t;
-- TODO: attempted better way of computing word size ran into type errors
function "+" (Left : sd_wchar_ptr; Right : size_t) return sd_wchar_ptr is
begin
return To_Sd_wchar_ptr (To_Address (Left) + Storage_Offset (Right) * 4);
end "+";
function Peek (From : sd_wchar_ptr) return char32_t is
begin
return To_Wchar_Ptr(From).all;
end Peek;
function Strlen (Item : sd_wchar_ptr) return size_t is
Item_Index : size_t := 0;
begin
if Item = Null then
raise Program_Error;
end if;
loop
if Peek (Item + Item_Index) = char32_nul then
return Item_Index;
end if;
Item_Index := Item_Index + 1;
end loop;
end Strlen;
function Value (Item : sd_wchar_ptr) return char32_array is
Result : char32_array (0 .. Strlen (Item));
begin
if Item = Null then
raise Program_Error;
end if;
Put_Line("String length " & size_t'image(Strlen(Item)));
-- Note that the following loop will also copy the terminating Nul
for J in Result'Range loop
Result (J) := Peek (Item + J);
end loop;
return Result;
end Value;
-- helper function to deal with wchar_t * to wide_wide_string
function Value (Item : access stddef_h.wchar_t) return Wide_Wide_String is
begin
return To_Ada (Value (sd_wchar_ptr(Item)));
end Value;

raised CONSTRAINT_ERROR : josephus.adb:50 index check failed

I'm trying to run this code, but something is going wrong with the line:
Soldiers (Number_Of_Soldiers) := Soldier_Type'(Name=>new String'(Line(1..Length)), Alive=>True);
Can someone help me, please?
Thank you so much!
--Josephus Problem
with Ada.Text_IO,Ada.Integer_Text_IO;
use Ada;
procedure Josephus is
type String_Pointer is access String;
type Soldier_Type is record
Name : String_Pointer;
Alive : Boolean;
end record;
Max_Number_Of_Soldiers: constant := 10;
Number_Of_Soldiers : Integer range 0..Max_Number_Of_Soldiers := 0;
-- start with 0 to facilitate modular arithmetic
Soldiers: array (0..Max_Number_Of_Soldiers-1) of Soldier_Type;
procedure Next (Index: in out Integer; Interval: Positive) is
begin
for I in 1..Interval loop
loop
Index := (Index + 1) mod Number_Of_Soldiers;
exit when Soldiers(Index).Alive;
end loop;
end loop;
end Next;
Interval : Integer;
Man : Integer := Soldiers'First;
begin
-- get interval from the standard input
Integer_Text_IO.Get (Interval);
Text_IO.Skip_Line;
Text_IO.Put ("Skip every ");
Integer_Text_IO.Put (Interval, Width=>1);
Text_IO.Put_Line (" soldiers.");
-- get names (one per line) from the standard input
declare
Line: String (1..10);
Length: Integer;
begin
while not (Text_IO.End_Of_File) loop
Text_IO.Get_Line (Line, Length);
Soldiers (Number_Of_Soldiers) := Soldier_Type'(Name=>new String'(Line(1..Length)), Alive=>True);
Number_Of_Soldiers := Number_Of_Soldiers + 1;
end loop;
end;
for I in 1..Number_Of_Soldiers-1 loop
Soldiers(Man).Alive := False;
Text_IO.Put (Soldiers(Man).Name.all);
Text_IO.Put_Line (" commits suicide.");
Next (Man, Interval);
end loop;
Text_IO.Put (Soldiers(Man).Name.all);
Text_IO.Put_Line (" is the last.");
end Josephus;
I think your problem is with the line
Max_Number_Of_Soldiers: constant := 10;
Obviously the number specified needs to be more than the maximum possible number of entries in your input!
The problem of unbounded input data sets is one reason to look at using Ada.Containers.Vectors instead of arrays.

Ada 95 Check if enter was pressed

I am new to Ada.
How can I check if enter was pressed?
The while loop should be able to check whether the input character is a white space or an enter key.
Furthermore, how can I check the user input type, like the type() or typeof() function in other languages?
FUNCTION ReadValue RETURN Unbounded_String IS
ValueChar : Character;
Result : Unbounded_String := To_Unbounded_String("NULL");
BEGIN
Get(ValueChar);
Skip_Line;
WHILE ValueChar /= ';'LOOP
Get(ValueChar);
IF IsValidNameInput(ValueChar) THEN
Result := Result & ValueChar;
ELSE
exit;
END IF;
END LOOP;
ValueIntegerFlag := CheckValue(Value);
RETURN Result;
END ReadValue;
Read the characters one-at-a-time without special ENTER handling using Get_Immediate instead of Get - ARM A.10.7(9).
You can do checks on the class of the character you’ve just read using Ada.Characters.Handling - ARM A.3.2 - something like
function Is_Valid_Name_Input (Ch : Character) return Boolean is
begin
return Ada.Characters.Handling.Is_Graphic (Ch)
and then not Ada.Characters.Handling.Is_Space (Ch);
end Is_Valid_Name_Input;
(probably not quite what you want, since it makes &*^$$^ a valid name!)
Ada.Characters.Handling.Is_Line_Terminator detects ENTER (on Unix; probably on Windows too).
You can check whether a string corresponds to an integer by trying the conversion and catching the exception when it fails:
function Check_Integer_Value (Str : Unbounded_String) return Boolean is
Dummy : Integer;
begin
Dummy := Integer'Value (To_String (Str));
return True;
exception
when Constraint_Error =>
return False;
end Check_Integer_Value;
With regard to ReadValue:
Don’t initialize Result - it starts off as the empty string (and you really don’t want to start with the string ”NULL”).
It skips the first character input.
What’s that Skip_Line for?
Try something like
function Read_Value return Unbounded_String is
Value_Char : Character;
Result : Unbounded_String;
begin
loop
Get_Immediate (Value_Char);
exit when Value_Char = ';';
if Is_Valid_Name_Input (Value_Char) then
Result := Result & Value_Char;
end if;
end loop;
return Result;
end Read_Value;

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