1 files changed, 74 insertions, 0 deletions
diff --git a/src/util/pool.cpp b/src/util/pool.cpp
new file mode 100644
index 0000000..c49b8ea
--- /dev/null
+++ b/src/util/pool.cpp
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include "pool.h"
+#include <cstdint>
+#include <cassert>
+
+namespace Inkscape {
+namespace Util {
+
+// Round up x to the next multiple of m.
+static std::byte *roundup(std::byte *x, std::size_t m)
+{
+    auto y = reinterpret_cast<uintptr_t>(x);
+    y = ((y - 1) / m + 1) * m;
+    return reinterpret_cast<std::byte*>(y);
+}
+
+std::byte *Pool::allocate(std::size_t size, std::size_t alignment)
+{
+    auto a = roundup(cur, alignment);
+    auto b = a + size;
+
+    if (b <= end) {
+        cur = b;
+        return a;
+    }
+
+    cursize = std::max(nextsize, size + alignment - 1);
+    buffers.emplace_back(std::make_unique<std::byte[]>(cursize));
+    // buffers.emplace_back(std::make_unique_for_overwrite<std::byte[]>(cursize)); // Todo: C++20.
+    resetblock();
+    nextsize = cursize * 3 / 2;
+
+    a = roundup(cur, alignment);
+    b = a + size;
+
+    assert(b <= end);
+    cur = b;
+    return a;
+};
+
+void Pool::free_all() noexcept
+{
+    if (buffers.empty()) return;
+    if (buffers.size() > 1) {
+        buffers.front() = std::move(buffers.back());
+        buffers.resize(1);
+    }
+    resetblock();
+}
+
+void Pool::movefrom(Pool &other) noexcept
+{
+    buffers = std::move(other.buffers);
+    cur = other.cur;
+    end = other.end;
+    cursize = other.cursize;
+    nextsize = other.nextsize;
+
+    other.buffers.clear();
+    other.cur = nullptr;
+    other.end = nullptr;
+    other.cursize = 0;
+    other.nextsize = 2;
+}
+
+void Pool::resetblock() noexcept
+{
+    assert(!buffers.empty());
+    cur = buffers.back().get();
+    end = cur + cursize;
+}
+
+} // namespace Util
+} // namespace Inkscape