Pica: Use some template magic to define register structures efficiently.

3 files changed, 166 insertions, 3 deletions

diff --git a/src/common/common.vcxproj b/src/common/common.vcxproj
index 86295a480..1f5c714c3 100644
--- a/src/common/common.vcxproj
+++ b/src/common/common.vcxproj
@@ -182,6 +182,7 @@
     <ClInclude Include="mem_arena.h" />
     <ClInclude Include="msg_handler.h" />
     <ClInclude Include="platform.h" />
+    <ClInclude Include="register_set.h" />
     <ClInclude Include="scm_rev.h" />
     <ClInclude Include="std_condition_variable.h" />
     <ClInclude Include="std_mutex.h" />
@@ -221,4 +222,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/common/common.vcxproj.filters b/src/common/common.vcxproj.filters
index 84cfa8837..e8c4ce360 100644
--- a/src/common/common.vcxproj.filters
+++ b/src/common/common.vcxproj.filters
@@ -4,6 +4,7 @@
     <ClInclude Include="atomic.h" />
     <ClInclude Include="atomic_gcc.h" />
     <ClInclude Include="atomic_win32.h" />
+    <ClInclude Include="bit_field.h" />
     <ClInclude Include="break_points.h" />
     <ClInclude Include="chunk_file.h" />
     <ClInclude Include="common.h" />
@@ -28,6 +29,7 @@
     <ClInclude Include="memory_util.h" />
     <ClInclude Include="msg_handler.h" />
     <ClInclude Include="platform.h" />
+    <ClInclude Include="register_set.h" />
     <ClInclude Include="std_condition_variable.h" />
     <ClInclude Include="std_mutex.h" />
     <ClInclude Include="std_thread.h" />
@@ -39,7 +41,6 @@
     <ClInclude Include="utf8.h" />
     <ClInclude Include="symbols.h" />
     <ClInclude Include="scm_rev.h" />
-    <ClInclude Include="bit_field.h" />
     <ClInclude Include="thread_queue_list.h" />
   </ItemGroup>
   <ItemGroup>
@@ -65,4 +66,4 @@
   <ItemGroup>
     <Text Include="CMakeLists.txt" />
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/common/register_set.h b/src/common/register_set.h
new file mode 100644
index 000000000..0418551b3
--- /dev/null
+++ b/src/common/register_set.h
@@ -0,0 +1,161 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+#pragma once
+
+// Copyright 2014 Tony Wasserka
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above copyright
+//       notice, this list of conditions and the following disclaimer in the
+//       documentation and/or other materials provided with the distribution.
+//     * Neither the name of the owner nor the names of its contributors may
+//       be used to endorse or promote products derived from this software
+//       without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/*
+ * Standardized way to define a group of registers and corresponding data structures. To define
+ * a new register set, first define struct containing an enumeration called "Id" containing
+ * all register IDs and a template union called "Struct". Specialize the Struct union for any
+ * register ID which needs to be accessed in a specialized way. You can then declare the object
+ * containing all register values using the RegisterSet<BaseType, DefiningStruct> type, where
+ * BaseType is the underlying type of each register (e.g. u32).
+ * Of course, you'll usually want to implement the Struct template such that they are of the same
+ * size as BaseType. However, it's also possible to make it larger, e.g. when you want to describe
+ * multiple registers with the same structure.
+ *
+ * Example:
+ *
+ *     struct Regs {
+ *         enum Id : u32 {
+ *             Value1 = 0,
+ *             Value2 = 1,
+ *             Value3 = 2,
+ *             NumIds = 3
+ *         };
+ *
+ *         // declare register definition structures
+ *         template<Id id>
+ *         union Struct;
+ *     };
+ *
+ *     // Define register set object
+ *     RegisterSet<u32, CommandIds> registers;
+ *
+ *     // define register definition structures
+ *     template<>
+ *     union Regs::Struct<Regs::Value1> {
+ *         BitField<0, 4, u32> some_field;
+ *         BitField<4, 3, u32> some_other_field;
+ *     };
+ *
+ * Usage in external code (within SomeNamespace scope):
+ *
+ *     For a register which maps to a single index:
+ *     registers.Get<Regs::Value1>().some_field = some_value;
+ *
+ *      For a register which maps to different indices, e.g. a group of similar registers
+ *     registers.Get<Regs::Value1>(index).some_field = some_value;
+ *
+ *
+ * @tparam BaseType Base type used for storing individual registers, e.g. u32
+ * @tparam RegDefinition Class defining an enumeration called "Id" and a template<Id id> union, as described above.
+ * @note RegDefinition::Id needs to have an enum value called NumIds defining the number of registers to be allocated.
+ */
+template<typename BaseType, typename RegDefinition>
+struct RegisterSet {
+    // Register IDs
+    using Id = typename RegDefinition::Id;
+
+    // type used for *this
+    using ThisType = RegisterSet<BaseType, RegDefinition>;
+
+    // Register definition structs, defined in RegDefinition
+    template<Id id>
+    using Struct = typename RegDefinition::template Struct<id>;
+
+
+    /*
+     * Lookup register with the given id and return it as the corresponding structure type.
+     * @note This just forwards the arguments to Get(Id).
+     */
+    template<Id id>
+    const Struct<id>& Get() const {
+        return Get<id>(id);
+    }
+
+    /*
+     * Lookup register with the given id and return it as the corresponding structure type.
+     * @note This just forwards the arguments to Get(Id).
+     */
+    template<Id id>
+    Struct<id>& Get() {
+        return Get<id>(id);
+    }
+
+    /*
+     * Lookup register with the given index and return it as the corresponding structure type.
+     * @todo Is this portable with regards to structures larger than BaseType?
+     * @note if index==id, you don't need to specify the function parameter.
+     */
+    template<Id id>
+    const Struct<id>& Get(const Id& index) const {
+        const int idx = static_cast<size_t>(index);
+        return *reinterpret_cast<const Struct<id>*>(&raw[idx]);
+    }
+
+    /*
+     * Lookup register with the given index and return it as the corresponding structure type.
+     * @note This just forwards the arguments to the const version of Get(Id).
+     * @note if index==id, you don't need to specify the function parameter.
+     */
+    template<Id id>
+    Struct<id>& Get(const Id& index) {
+        return const_cast<Struct<id>&>(GetThis().Get<id>(index));
+    }
+
+    /*
+     * Plain array access.
+     * @note If you want to have this casted to a register defininition struct, use Get() instead.
+     */
+    const BaseType& operator[] (const Id& id) const {
+        return raw[static_cast<size_t>(id)];
+    }
+
+    /*
+     * Plain array access.
+     * @note If you want to have this casted to a register defininition struct, use Get() instead.
+     * @note This operator just forwards its argument to the const version.
+     */
+    BaseType& operator[] (const Id& id) {
+        return const_cast<BaseType&>(GetThis()[id]);
+    }
+
+private:
+    /*
+     * Returns a const reference to "this".
+     */
+    const ThisType& GetThis() const {
+        return static_cast<const ThisType&>(*this);
+    }
+
+    BaseType raw[Id::NumIds];
+};