From cbff7c386a820a5ab9e12c3228957b91959bc6c6 Mon Sep 17 00:00:00 2001
From: FalseHonesty <thefalsehonesty@gmail.com>
Date: Sat, 26 Jun 2021 16:28:25 -0400
Subject: LibVideo/VP9: Refactor how above & left contexts are stored & cleared

These make more sense as Vectors, and it makes it much easier to manage
their sizing.
---
 Userland/Libraries/LibVideo/VP9/Decoder.cpp | 45 +++++++++++------------------
 Userland/Libraries/LibVideo/VP9/Decoder.h   | 17 ++++++-----
 2 files changed, 27 insertions(+), 35 deletions(-)

diff --git a/Userland/Libraries/LibVideo/VP9/Decoder.cpp b/Userland/Libraries/LibVideo/VP9/Decoder.cpp
index 8511dad917..447521ed00 100644
--- a/Userland/Libraries/LibVideo/VP9/Decoder.cpp
+++ b/Userland/Libraries/LibVideo/VP9/Decoder.cpp
@@ -719,20 +719,25 @@ bool Decoder::decode_tiles()
     return true;
 }
 
-template<typename T>
-void clear_context(T* context, size_t size)
+void Decoder::clear_context(Vector<u8>& context, size_t size)
 {
-    if (!(*context))
-        *context = static_cast<T>(malloc(size));
-    else
-        __builtin_memset(*context, 0, size);
+    context.resize_and_keep_capacity(size);
+    __builtin_memset(context.data(), 0, sizeof(u8) * size);
+}
+
+void Decoder::clear_context(Vector<Vector<u8>>& context, size_t outer_size, size_t inner_size)
+{
+    if (context.size() < outer_size)
+        context.resize(outer_size);
+    for (auto& sub_vector : context)
+        clear_context(sub_vector, inner_size);
 }
 
 bool Decoder::clear_above_context()
 {
-    clear_context(&m_above_nonzero_context, sizeof(u8) * 3 * m_mi_cols * 2);
-    clear_context(&m_above_seg_pred_context, sizeof(u8) * m_mi_cols);
-    clear_context(&m_above_partition_context, sizeof(u8) * m_sb64_cols * 8);
+    clear_context(m_above_nonzero_context, 2 * m_mi_cols, 3);
+    clear_context(m_above_seg_pred_context, m_mi_cols);
+    clear_context(m_above_partition_context, m_sb64_cols * 8);
     return true;
 }
 
@@ -758,9 +763,9 @@ bool Decoder::decode_tile()
 
 bool Decoder::clear_left_context()
 {
-    clear_context(&m_left_nonzero_context, sizeof(u8) * 3 * m_mi_rows * 2);
-    clear_context(&m_left_seg_pred_context, sizeof(u8) * m_mi_rows);
-    clear_context(&m_left_partition_context, sizeof(u8) * m_sb64_rows * 8);
+    clear_context(m_left_nonzero_context, 2 * m_mi_rows, 3);
+    clear_context(m_left_seg_pred_context, m_mi_rows);
+    clear_context(m_left_partition_context, m_sb64_rows * 8);
     return true;
 }
 
@@ -1125,20 +1130,4 @@ void Decoder::dump_info()
     dbgln("Interpolation filter: {}", (u8)m_interpolation_filter);
 }
 
-Decoder::~Decoder()
-{
-    if (m_above_nonzero_context)
-        free(m_above_nonzero_context);
-    if (m_left_nonzero_context)
-        free(m_left_nonzero_context);
-    if (m_above_seg_pred_context)
-        free(m_above_seg_pred_context);
-    if (m_left_seg_pred_context)
-        free(m_left_seg_pred_context);
-    if (m_above_partition_context)
-        free(m_above_partition_context);
-    if (m_left_partition_context)
-        free(m_left_partition_context);
-}
-
 }
diff --git a/Userland/Libraries/LibVideo/VP9/Decoder.h b/Userland/Libraries/LibVideo/VP9/Decoder.h
index fa57eed26b..f10709bd21 100644
--- a/Userland/Libraries/LibVideo/VP9/Decoder.h
+++ b/Userland/Libraries/LibVideo/VP9/Decoder.h
@@ -21,7 +21,6 @@ class Decoder {
 
 public:
     Decoder();
-    ~Decoder();
     bool parse_frame(ByteBuffer const&);
     void dump_info();
 
@@ -40,6 +39,10 @@ private:
         return StudioSwing;
     }
 
+    /* Utilities */
+    void clear_context(Vector<u8>& context, size_t size);
+    void clear_context(Vector<Vector<u8>>& context, size_t outer_size, size_t inner_size);
+
     /* (6.2) Uncompressed Header Syntax */
     bool uncompressed_header();
     bool frame_sync_code();
@@ -158,12 +161,12 @@ private:
     i8 m_loop_filter_ref_deltas[MAX_REF_FRAMES];
     i8 m_loop_filter_mode_deltas[2];
 
-    u8** m_above_nonzero_context { nullptr };
-    u8** m_left_nonzero_context { nullptr };
-    u8* m_above_seg_pred_context { nullptr };
-    u8* m_left_seg_pred_context { nullptr };
-    u8* m_above_partition_context { nullptr };
-    u8* m_left_partition_context { nullptr };
+    Vector<Vector<u8>> m_above_nonzero_context;
+    Vector<Vector<u8>> m_left_nonzero_context;
+    Vector<u8> m_above_seg_pred_context;
+    Vector<u8> m_left_seg_pred_context;
+    Vector<u8> m_above_partition_context;
+    Vector<u8> m_left_partition_context;
     u32 m_mi_row_start { 0 };
     u32 m_mi_row_end { 0 };
     u32 m_mi_col_start { 0 };
-- 
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