add arena allocator

3 files changed, 81 insertions, 27 deletions

diff --git a/src/common/Arena.hpp b/src/common/Arena.hpp
new file mode 100644
index 0000000..b5e1eb7
--- /dev/null
+++ b/src/common/Arena.hpp
@@ -0,0 +1,53 @@
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <cassert>
+
+#include <vector>
+
+
+class Arena {
+public:
+    Arena(size_t size) : buffer(size)
+    {
+    }
+
+    template<typename T>
+    size_t
+    Align() const
+    {
+        size_t alignment = alignof(T);
+        return (offset + alignment - 1) & ~(alignment - 1);
+    }
+
+    template<typename T, typename... Args>
+    T&
+    Allocate(Args&&... args)
+    {
+        offset = Align<T>();
+        assert(offset + sizeof(T) <= buffer.size() && "Arena out of memory");
+
+        T* ptr = new (&buffer[offset]) T(std::forward<Args>(args)...);
+        objects.emplace_back(ptr, [](void* p) { static_cast<T*>(p)->~T(); });
+
+        offset += sizeof(T);
+        return *ptr;
+    }
+
+    void
+    Reset()
+    {
+        for (auto& [ptr, dtor] : objects) {
+            dtor(ptr);
+        }
+        objects.clear();
+        offset = 0;
+    }
+
+
+    size_t offset = 0;
+    std::vector<uint8_t> buffer;
+    std::vector<std::pair<void*, void (*)(void*)>> objects;
+};
+
diff --git a/src/games/tetris/Tetris.cpp b/src/games/tetris/Tetris.cpp
index 2413dd1..b59d1e9 100644
--- a/src/games/tetris/Tetris.cpp
+++ b/src/games/tetris/Tetris.cpp
@@ -9,6 +9,7 @@
 
 #include <fstream>
 #include <iostream>
+#include <string>
 
 
 static 
@@ -25,7 +26,6 @@ Tetris::Tetris()
     , m_active_tetromino{m_board.m_bitmap}
     , m_highscore {ReadHighscore()}
 {
-    m_frame_strings.reserve(s_frame_strings_capacity);
 }
 
 void
@@ -51,18 +51,18 @@ Tetris::Start()
 bool
 Tetris::Update(std::vector<SDL_Event>& events)
 {
-    Color clear_color = {0.2f, 0.2f, 0.2f, 1.0f};
-    g_renderer.SetCameraSize(4.0f, 3.0f);
-    g_renderer.Clear(clear_color);
-
-    m_frame_strings.clear();
-
+    m_frame_arena.Reset();
 
     if (m_game_status == game_starting) {
         Start();
     }
 
 
+    Color clear_color = {0.2f, 0.2f, 0.2f, 1.0f};
+    g_renderer.SetCameraSize(4.0f, 3.0f);
+    g_renderer.Clear(clear_color);
+
+
     float dt = ProcessDt();
 
 
@@ -93,8 +93,6 @@ Tetris::Update(std::vector<SDL_Event>& events)
 
     Draw();
 
-    assert((float)m_frame_strings.size() <= 0.8f * s_frame_strings_capacity);
-
 
     return true;
 }
@@ -272,7 +270,7 @@ Tetris::DrawGameOverMenu()
 void
 Tetris::DrawLineCounter()
 {
-    static std::u32string text = U"Lines: xxx";
+    std::u32string& text = m_frame_arena.Allocate<std::u32string>(U"Lines: xxx");
     V3F32 pos = {0.5f, 2.6f, 4.0f};
     Color color = {0.9f, 0.9f, 0.9f, 1.0f};
 
@@ -296,11 +294,10 @@ Tetris::DrawStatistics()
     V3F32 pos = {0.4f, 0.5f, s_text_z};
 
 
-    static std::u32string title_text = U"Statistics";
+    std::u32string& title_text = m_frame_arena.Allocate<std::u32string>(U"Statistics");
     V3F32 title_pos = {pos.x + 0.02f, pos.y + 1.64f, pos.z};
     g_renderer.PushText(title_text, m_font, title_pos, s_text_color);
 
-
     float yadvance = -0.2f;
     float tetrominoes_x0 = pos.x;
     float tetrominoes_y0 = pos.y - (float)Tetromino::id_count * yadvance;
@@ -328,17 +325,19 @@ Tetris::DrawStatistics()
     tetromino_pos.y += yadvance;
 
 
+    // Todo: reorder tetrominoes' bitmaps and just for-loop this?
+
     float counters_x0 = pos.x + 0.4f;
     float counters_y0 = pos.y + 0.05f - yadvance * (float)Tetromino::id_count;
     V3F32 counters_pos = {counters_x0, counters_y0, s_text_z};
 
-    std::u32string& t_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::t_piece]));
-    std::u32string& j_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::j_piece]));
-    std::u32string& z_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::z_piece]));
-    std::u32string& o_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::o_piece]));
-    std::u32string& s_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::s_piece]));
-    std::u32string& l_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::l_piece]));
-    std::u32string& i_count = m_frame_strings.emplace_back(int32_to_u32string(m_tetromino_counters[Tetromino::i_piece]));
+    std::u32string& t_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::t_piece]));
+    std::u32string& j_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::j_piece]));
+    std::u32string& z_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::z_piece]));
+    std::u32string& o_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::o_piece]));
+    std::u32string& s_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::s_piece]));
+    std::u32string& l_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::l_piece]));
+    std::u32string& i_count = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_tetromino_counters[Tetromino::i_piece]));
 
     g_renderer.PushText(t_count, m_font, counters_pos, s_text_color);
     counters_pos.y += yadvance;
@@ -361,11 +360,11 @@ Tetris::DrawScore()
     V3F32 pos = {3.0f, 2.6f, s_text_z};
 
 
-    std::u32string& top_label = m_frame_strings.emplace_back(U"Top");
-    std::u32string& top_value = m_frame_strings.emplace_back(int32_to_u32string(m_highscore));
+    std::u32string& top_label = m_frame_arena.Allocate<std::u32string>(U"Top");
+    std::u32string& top_value = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_highscore));
 
-    std::u32string& score_label = m_frame_strings.emplace_back(U"Score");
-    std::u32string& score_value = m_frame_strings.emplace_back(int32_to_u32string(m_score));
+    std::u32string& score_label = m_frame_arena.Allocate<std::u32string>(U"Score");
+    std::u32string& score_value = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_score));
 
 
     g_renderer.PushText(top_label, m_font, pos, s_text_color);
@@ -385,7 +384,7 @@ Tetris::DrawNextTetromino()
 
 
     V3F32 label_pos = {pos.x, pos.y + 0.4f, pos.z};
-    std::u32string& label_text = m_frame_strings.emplace_back(U"Next:");
+    std::u32string& label_text = m_frame_arena.Allocate<std::u32string>(U"Next:");
     g_renderer.PushText(label_text, m_font, label_pos, s_text_color);
 
 
@@ -398,11 +397,11 @@ Tetris::DrawLevel()
 {
     V3F32 pos = {3.0f, 1.1f};
 
-    std::u32string& label = m_frame_strings.emplace_back(U"Level");
+    std::u32string& label = m_frame_arena.Allocate<std::u32string>(U"Level");
     g_renderer.PushText(label, m_font, pos, s_text_color);
     pos.y -= 0.1f;
 
-    std::u32string& level = m_frame_strings.emplace_back(int32_to_u32string(m_level));
+    std::u32string& level = m_frame_arena.Allocate<std::u32string>(int32_to_u32string(m_level));
     g_renderer.PushText(level, m_font, pos, s_text_color);
 }
 
diff --git a/src/games/tetris/Tetris.hpp b/src/games/tetris/Tetris.hpp
index 2d1dfba..1c60a98 100644
--- a/src/games/tetris/Tetris.hpp
+++ b/src/games/tetris/Tetris.hpp
@@ -1,9 +1,11 @@
 #pragma once
 
+#include <common/defs.hpp>
 #include <games/Game.hpp>
 #include <games/tetris/Tetromino.hpp>
 #include <games/tetris/Board.hpp>
 #include <common/Font.hpp>
+#include <common/Arena.hpp>
 
 
 class Tetris : public Game {
@@ -51,7 +53,7 @@ private:
     int32_t m_softdrop_counter = 0;
     int32_t m_highscore = 0;
 
-    std::vector<std::u32string> m_frame_strings;
+    Arena m_frame_arena {KIBIBYTES(2)};
 };