3 files changed, 214 insertions, 0 deletions
diff --git a/kernel/src/devices/storage/ram_disk/controller.cpp b/kernel/src/devices/storage/ram_disk/controller.cpp
new file mode 100644
index 0000000..30441fa
--- /dev/null
+++ b/kernel/src/devices/storage/ram_disk/controller.cpp
@@ -0,0 +1,27 @@
+#include <kernel/devices/storage/ram_disk/controller.hpp>
+
+#include <kernel/devices/storage/ram_disk/device.hpp>
+
+#include <kapi/boot_module/boot_module_registry.hpp>
+
+#include <kstd/memory>
+
+#include <algorithm>
+#include <cstddef>
+
+namespace kernel::devices::storage::ram_disk
+{
+  controller::controller(kapi::boot_modules::boot_module_registry const * registry)
+      : m_boot_module_registry(registry)
+  {}
+
+  auto controller::probe() -> void
+  {
+    size_t current_device_index = 0;
+
+    std::ranges::for_each(*m_boot_module_registry, [this, &current_device_index](auto const & module) {
+      auto const minor = current_device_index++ * m_minors_per_device;
+      m_devices.push_back(kstd::make_shared<device>(module, m_major, minor));
+    });
+  }
+}  // namespace kernel::devices::storage::ram_disk
+\ No newline at end of file
diff --git a/kernel/src/devices/storage/ram_disk/device.cpp b/kernel/src/devices/storage/ram_disk/device.cpp
new file mode 100644
index 0000000..1557204
--- /dev/null
+++ b/kernel/src/devices/storage/ram_disk/device.cpp
@@ -0,0 +1,71 @@
+#include <kernel/devices/storage/ram_disk/device.hpp>
+
+#include <kernel/devices/block_device.hpp>
+
+#include <kapi/boot_module/boot_module.hpp>
+#include <kapi/system.hpp>
+
+#include <kstd/cstring>
+#include <kstd/string>
+
+#include <cstddef>
+
+namespace kernel::devices::storage::ram_disk
+{
+  namespace
+  {
+    constexpr size_t ram_disk_block_size = 512uz;
+  }  // namespace
+
+  device::device(kapi::boot_modules::boot_module const & module, size_t major, size_t minor)
+      : block_device(major, minor, "ram" + kstd::to_string(minor), ram_disk_block_size)
+      , m_boot_module(module)
+  {}
+
+  auto device::init() -> bool
+  {
+    return m_boot_module.start_address.raw() != 0 && m_boot_module.size > 0;
+  }
+
+  auto device::read_block(size_t block_index, void * buffer) const -> void
+  {
+    if (buffer == nullptr)
+    {
+      kapi::system::panic("[RAM DISK DEVICE] read_block called with null buffer.");
+    }
+
+    auto const info = calculate_transfer(block_index);
+
+    if (info.to_transfer > 0)
+    {
+      auto const src = static_cast<std::byte const *>(m_boot_module.start_address) + info.offset;
+      kstd::libc::memcpy(buffer, src, info.to_transfer);
+    }
+
+    if (info.remainder > 0)
+    {
+      kstd::libc::memset(static_cast<std::byte *>(buffer) + info.to_transfer, 0, info.remainder);
+    }
+  }
+
+  auto device::write_block(size_t block_index, void const * buffer) -> void
+  {
+    if (buffer == nullptr)
+    {
+      kapi::system::panic("[RAM DISK DEVICE] write_block called with null buffer.");
+    }
+
+    auto const info = calculate_transfer(block_index);
+
+    if (info.to_transfer > 0)
+    {
+      auto const dest = static_cast<std::byte *>(m_boot_module.start_address) + info.offset;
+      kstd::libc::memcpy(dest, buffer, info.to_transfer);
+    }
+  }
+
+  auto device::size() const -> size_t
+  {
+    return m_boot_module.size;
+  }
+}  // namespace kernel::devices::storage::ram_disk
+\ No newline at end of file
diff --git a/kernel/src/devices/storage/ram_disk/device.tests.cpp b/kernel/src/devices/storage/ram_disk/device.tests.cpp
new file mode 100644
index 0000000..d0fab76
--- /dev/null
+++ b/kernel/src/devices/storage/ram_disk/device.tests.cpp
@@ -0,0 +1,116 @@
+#include <kernel/devices/storage/ram_disk/device.hpp>
+
+#include <kapi/boot_module/boot_module.hpp>
+#include <kapi/memory.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers.hpp>
+#include <catch2/matchers/catch_matchers_range_equals.hpp>
+
+#include <cstddef>
+#include <ranges>
+#include <stdexcept>
+#include <vector>
+
+SCENARIO("RAM Disk Device Construction and Initialization", "[ram_disk_device]")
+{
+  GIVEN("an empty boot module")
+  {
+    kapi::boot_modules::boot_module boot_module{};
+    boot_module.start_address = kapi::memory::linear_address{nullptr};
+    boot_module.size = 0;
+
+    WHEN("constructing the device")
+    {
+      kernel::devices::storage::ram_disk::device device{boot_module, 0, 0};
+
+      THEN("init return false")
+      {
+        REQUIRE_FALSE(device.init());
+      }
+    }
+  }
+
+  GIVEN("a boot module with a valid start address and size")
+  {
+    kapi::boot_modules::boot_module boot_module{};
+    boot_module.start_address = kapi::memory::linear_address{reinterpret_cast<std::byte *>(0x1000)};
+    boot_module.size = 512;
+
+    WHEN("constructing the device")
+    {
+      kernel::devices::storage::ram_disk::device device{boot_module, 0, 0};
+
+      THEN("init return true")
+      {
+        REQUIRE(device.init());
+      }
+    }
+  }
+}
+
+SCENARIO("RAM Disk Device Read and Write", "[ram_disk_device]")
+{
+  GIVEN("a device initialized with a valid boot module")
+  {
+    auto storage = std::vector{4096, std::byte{0xff}};
+    auto module =
+        kapi::boot_modules::boot_module{"test_module", kapi::memory::linear_address{storage.data()}, storage.size()};
+    auto device = kernel::devices::storage::ram_disk::device{module, 0, 0};
+    REQUIRE(device.init());
+
+    WHEN("reading a full block from the device")
+    {
+      auto buffer = std::vector<std::byte>(device.block_size());
+      device.read_block(0, buffer.data());
+
+      THEN("the buffer is filled with the module data")
+      {
+        REQUIRE_THAT(buffer, Catch::Matchers::RangeEquals(std::views::take(storage, device.block_size())));
+      }
+    }
+
+    WHEN("reading from a block index beyond the module size")
+    {
+      auto buffer = std::vector<std::byte>(device.block_size());
+      device.read_block(10, buffer.data());
+
+      THEN("the buffer is filled with zeros")
+      {
+        REQUIRE_THAT(buffer, Catch::Matchers::RangeEquals(std::vector<std::byte>(device.block_size(), std::byte{0})));
+      }
+    }
+
+    WHEN("reading into a null buffer")
+    {
+      REQUIRE_THROWS_AS(device.read_block(0, nullptr), std::runtime_error);
+    }
+
+    WHEN("writing to a full block")
+    {
+      auto buffer = std::vector<std::byte>(device.block_size(), std::byte{0x01});
+      device.write_block(0, buffer.data());
+
+      THEN("the module data is updated")
+      {
+        REQUIRE_THAT(std::views::take(storage, device.block_size()), Catch::Matchers::RangeEquals(buffer));
+      }
+    }
+
+    WHEN("writing to a block index beyond the module size")
+    {
+      auto buffer = std::vector<std::byte>(device.block_size(), std::byte{0x01});
+      device.write_block(10, buffer.data());
+
+      THEN("the module data is not updated")
+      {
+        REQUIRE_THAT(storage, Catch::Matchers::RangeEquals(std::vector{4096, std::byte{0xff}}));
+      }
+    }
+
+    WHEN("writing from a null buffer")
+    {
+      REQUIRE_THROWS_AS(device.write_block(0, nullptr), std::runtime_error);
+    }
+  }
+}
+\ No newline at end of file