add util::Aligned_memory_allocator

diff --git a/src/util/memory.h b/src/util/memory.h
new file mode 100644 (file)
index 0000000..08081a6
--- /dev/null
+++ b/src/util/memory.h
@@ -0,0 +1,107 @@
+/*
+ * Copyright 2017 Jacob Lifshay
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#ifndef UTIL_MEMORY_H_
+#define UTIL_MEMORY_H_
+
+#include <cstddef>
+#include <new>
+#include <cstdint>
+
+namespace vulkan_cpu
+{
+namespace util
+{
+namespace detail
+{
+constexpr std::size_t get_max_align_alignment() noexcept
+{
+    using namespace std;
+    // not all standard libraries properly put max_align_t in std
+    return alignof(max_align_t);
+}
+
+template <std::size_t Alignment, bool Needs_adjusting = (Alignment > get_max_align_alignment())>
+struct Aligned_memory_allocator_base
+{
+    static_assert(Alignment != 0 && (Alignment & (Alignment - 1)) == 0, "non-power-of-2 Alignment");
+    static void *allocate(std::size_t size)
+    {
+        return new unsigned char[size];
+    }
+    static void deallocate(void *p) noexcept
+    {
+        delete[] static_cast<unsigned char *>(p);
+    }
+};
+
+template <std::size_t Alignment>
+struct Aligned_memory_allocator_base<Alignment, true>
+{
+    static_assert(Alignment != 0 && (Alignment & (Alignment - 1)) == 0, "non-power-of-2 Alignment");
+    typedef unsigned char *Base_pointer;
+    static constexpr std::size_t extra_size = Alignment + sizeof(Base_pointer);
+    static void *allocate(std::size_t size)
+    {
+        size += extra_size;
+        Base_pointer base = new unsigned char[size];
+        auto alignment_start = reinterpret_cast<std::uintptr_t>(base + sizeof(Base_pointer));
+        auto retval =
+            reinterpret_cast<unsigned char *>((alignment_start + Alignment - 1) & (Alignment - 1));
+        auto base_location = reinterpret_cast<Base_pointer *>(retval) - 1;
+        *base_location = base;
+        return retval;
+    }
+    static void deallocate(void *p) noexcept
+    {
+        if(p != nullptr)
+        {
+            auto base_location = reinterpret_cast<Base_pointer *>(p) - 1;
+            delete[] * base_location;
+        }
+    }
+};
+}
+
+template <std::size_t Alignment>
+struct Aligned_memory_allocator
+{
+    static void *allocate(std::size_t size)
+    {
+        return detail::Aligned_memory_allocator_base<Alignment>::allocate(size);
+    }
+    static void deallocate(void *p) noexcept
+    {
+        return detail::Aligned_memory_allocator_base<Alignment>::deallocate(p);
+    }
+    struct Deleter
+    {
+        void operator()(void *p) const noexcept
+        {
+            deallocate(p);
+        }
+    };
+};
+}
+}
+
+#endif // UTIL_MEMORY_H_