1 files changed, 70 insertions, 0 deletions
diff --git a/kernel/src/test_support/page_mapper.cpp b/kernel/src/test_support/page_mapper.cpp
new file mode 100644
index 0000000..3d50ff1
--- /dev/null
+++ b/kernel/src/test_support/page_mapper.cpp
@@ -0,0 +1,70 @@
+#include <kernel/test_support/page_mapper.hpp>
+
+#include <kapi/memory.hpp>
+
+#include <kstd/units>
+
+#include <cstddef>
+#include <format>
+#include <stdexcept>
+
+namespace kernel::tests
+{
+
+  page_mapper::page_mapper(kstd::units::bytes physical_size, kstd::units::bytes virtual_size)
+      : memory{physical_size, virtual_size}
+  {}
+
+  auto page_mapper::map(kapi::memory::page page, kapi::memory::frame frame, flags) -> std::byte *
+  {
+    auto result = page_mappings.insert({page.number(), frame});
+    if (!result.second)
+    {
+      auto error = std::format("Page {} was already mapped!", page.number());
+      throw std::invalid_argument{error};
+    }
+
+    auto page_address = page.start_address();
+    auto virtual_base = memory.virtual_base();
+    auto virtual_end = virtual_base + memory.virtual_size();
+
+    if (page_address >= virtual_base && page_address < virtual_end)
+    {
+      auto virtual_target = static_cast<std::byte *>(page_address);
+      auto physical_offset = frame.number() * kapi::memory::frame::size;
+      return memory.map(kapi::memory::page::size, virtual_target, physical_offset.value);
+    }
+    else if (page_address >= kapi::memory::mmio_base)
+    {
+      throw std::runtime_error("MMIO mapping not yet supported in testing!");
+    }
+    else if (page_address >= kapi::memory::higher_half_direct_map_base)
+    {
+      auto offset = frame.number() * kapi::memory::frame::size;
+      return memory.physical_base() + offset;
+    }
+
+    return nullptr;
+  }
+
+  auto page_mapper::unmap(kapi::memory::page page) -> void
+  {
+    if (!try_unmap(page))
+    {
+      auto error = std::format("Page {} was never mapped!", page.number());
+      throw std::invalid_argument{error};
+    }
+  }
+
+  auto page_mapper::try_unmap(kapi::memory::page page) noexcept -> bool
+  {
+    if (page_mappings.contains(page.number()))
+    {
+      page_mappings.erase(page.number());
+      return true;
+    }
+
+    return false;
+  }
+
+}  // namespace kernel::tests
+\ No newline at end of file