LibVideo/VP9: Begin creating a tree parser to parse syntax elements

Userland/Libraries/LibVideo/VP9/TreeParser.h

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2021, Hunter Salyer <thefalsehonesty@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "BitStream.h"
+#include "Enums.h"
+#include "ProbabilityTables.h"
+#include "SyntaxElementCounter.h"
+
+namespace Video::VP9 {
+
+class TreeParser {
+public:
+    explicit TreeParser(ProbabilityTables& probability_tables)
+        : m_probability_tables(probability_tables)
+    {
+    }
+
+    class TreeSelection {
+    public:
+        union TreeSelectionValue {
+            const int* m_tree;
+            int m_value;
+        };
+
+        TreeSelection(const int* values);
+        TreeSelection(int value);
+
+        bool is_single_value() const { return m_is_single_value; }
+        int get_single_value() const { return m_value.m_value; }
+        const int* get_tree_value() const { return m_value.m_tree; }
+
+    private:
+        bool m_is_single_value;
+        TreeSelectionValue m_value;
+    };
+
+    int parse_tree(SyntaxElementType type);
+    TreeSelection select_tree(SyntaxElementType type);
+    u8 select_tree_probability(SyntaxElementType type, u8 node);
+
+    void set_bit_stream(BitStream* bit_stream) { m_bit_stream = bit_stream; }
+    void set_has_rows(bool has_rows) { m_has_rows = has_rows; }
+    void set_has_cols(bool has_cols) { m_has_cols = has_cols; }
+    void set_max_tx_size(TXSize max_tx_size) { m_max_tx_size = max_tx_size; }
+    void set_use_hp(bool use_hp) { m_use_hp = use_hp; }
+    void set_block_subsize(u8 block_subsize) { m_block_subsize = block_subsize; }
+    void set_num_8x8(u8 num_8x8) { m_num_8x8 = num_8x8; }
+    void set_above_partition_context(u8* above_partition_context) { m_above_partition_context = above_partition_context; }
+    void set_left_partition_context(u8* left_partition_context) { m_left_partition_context = left_partition_context; }
+    void set_col(u32 col) { m_col = col; }
+    void set_row(u32 row) { m_row = row; }
+    void set_frame_is_intra(bool frame_is_intra) { m_frame_is_intra = frame_is_intra; }
+
+private:
+    u8 calculate_partition_probability(u8 node);
+
+    ProbabilityTables& m_probability_tables;
+    BitStream* m_bit_stream { nullptr };
+
+    bool m_has_rows { false };
+    bool m_has_cols { false };
+    TXSize m_max_tx_size { TX_4x4 };
+    bool m_use_hp { false };
+    u8 m_block_subsize { 0 };
+    u8 m_num_8x8 { 0 };
+    u8* m_above_partition_context { nullptr };
+    u8* m_left_partition_context { nullptr };
+    u32 m_col { 0 };
+    u32 m_row { 0 };
+    bool m_frame_is_intra { false };
+};
+
+}