From f447e5e6b43326645a4990f2039ba728581c6f06 Mon Sep 17 00:00:00 2001
From: rexim <reximkut@gmail.com>
Date: Sun, 17 Mar 2024 00:07:38 +0700
Subject: Implement custom ring buffer style queue

---
 build.sh  |  2 +-
 queue.adb | 43 +++++++++++++++++++++++++++++++++++++++++++
 queue.ads | 18 ++++++++++++++++++
 test.adb  | 31 +++++++++++++++++--------------
 4 files changed, 79 insertions(+), 15 deletions(-)
 create mode 100644 queue.adb
 create mode 100644 queue.ads

diff --git a/build.sh b/build.sh
index fe10404..e276754 100755
--- a/build.sh
+++ b/build.sh
@@ -2,7 +2,7 @@
 
 set -xe
 
-gnatmake -O3 -Wall -Wextra -gnat2022 game.adb -largs -L./raylib/raylib-5.0_linux_amd64/lib/ -l:libraylib.a -lm
+gnatmake -Wall -Wextra -gnat2022 game.adb -largs -L./raylib/raylib-5.0_linux_amd64/lib/ -l:libraylib.a -lm
 ./game
 
 # gnatmake -gnat2022 test.adb
diff --git a/queue.adb b/queue.adb
new file mode 100644
index 0000000..a758224
--- /dev/null
+++ b/queue.adb
@@ -0,0 +1,43 @@
+with Ada.Unchecked_Deallocation;
+
+package body Queue is
+    procedure Delete_Items_Array is new Ada.Unchecked_Deallocation(Items_Array, Items_Array_Access);
+
+    procedure Grow(Q: in out Queue) is
+        New_Items: Items_Array_Access := new Items_Array(0..Q.Items'Length*2-1);
+    begin
+        for Offset in Q.Items'Range loop
+            New_Items(Offset) := Q.Items((Q.Start + Offset) mod Q.Items'Length);
+        end loop;
+        Delete_Items_Array(Q.Items);
+        Q.Items := New_Items;
+        Q.Start := 0;
+    end;
+
+    procedure Enqueue(Q: in out Queue; X: Item) is
+    begin
+        if Q.Items = null then
+            Q.Items := new Items_Array(0..INIT_CAPACITY-1);
+        end if;
+
+        if Q.Count >= Q.Items'Length then
+            Grow(Q);
+        end if;
+
+        Q.Items((Q.Start + Q.Count) mod Q.Items'Length) := X;
+        Q.Count := Q.Count + 1;
+    end;
+
+    function Dequeue(Q: in out Queue; X: out Item) return Boolean is
+    begin
+        if Q.Count <= 0 then
+            return False;
+        end if;
+
+        X := Q.Items(Q.Start);
+        Q.Start := (Q.Start + 1) mod Q.Items'Length;
+        Q.Count := Q.Count - 1;
+
+        return True;
+    end;
+end Queue;
diff --git a/queue.ads b/queue.ads
new file mode 100644
index 0000000..fdfa484
--- /dev/null
+++ b/queue.ads
@@ -0,0 +1,18 @@
+generic
+    type Item is private;
+package Queue is
+    INIT_CAPACITY: constant Integer := 256;
+
+    type Items_Array is array (Natural range <>) of Item;
+    type Items_Array_Access is access Items_Array;
+
+    type Queue is record
+        Items: Items_Array_Access := null;
+        Start: Integer := 0;
+        Count: Integer := 0;
+    end record;
+
+    procedure Grow(Q: in out Queue);
+    procedure Enqueue(Q: in out Queue; X: Item);
+    function Dequeue(Q: in out Queue; X: out Item) return Boolean;
+end Queue;
diff --git a/test.adb b/test.adb
index 115d24e..c74e193 100644
--- a/test.adb
+++ b/test.adb
@@ -4,21 +4,24 @@ with Ada.Strings.Fixed; use Ada.Strings.Fixed;
 with Ada.Strings; use Ada.Strings;
 with Ada.Containers.Vectors;
 with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
+with Queue;
 
 procedure Test is
-    type State is record
-        X: Integer;
-        Y: Integer;
-    end record;
-
-    procedure Foo(S: in State; V: out Integer) is
-    begin
-        V := S.X*2;
-    end;
-
-    S: State := (X => 69, Y => 420);
+    package String_Queue is new Queue(Item => Unbounded_String);
+    use String_Queue;
+    Q: String_Queue.Queue;
+    X: Unbounded_String;
 begin
-    Put_Line(S'Image);
-    Foo(S, S.Y);
-    Put_Line(S'Image);
+    for Index in 1..16 loop
+        Enqueue(Q, To_Unbounded_String(Index'Image));
+    end loop;
+    while Dequeue(Q, X) loop
+        null;
+    end loop;
+    for Index in 32..42 loop
+        Enqueue(Q, To_Unbounded_String(Index'Image));
+    end loop;
+    while Dequeue(Q, X) loop
+        Put_Line(To_String(X));
+    end loop;
 end;
-- 
cgit v1.2.3