1 files changed, 92 insertions, 0 deletions
diff --git a/src/multiboot.cpp b/src/multiboot.cpp
new file mode 100644
index 0000000..46c505b
--- /dev/null
+++ b/src/multiboot.cpp
@@ -0,0 +1,92 @@
+#include "textoutput.hpp"
+
+#include <cstdint>
+
+extern TextOutput& term;
+
+struct multiboot2_tag
+{
+    alignas(8)
+    std::uint16_t id;
+    std::uint16_t flags;
+    std::uint32_t length;
+    std::uint32_t data[1];
+} __attribute__((packed));
+
+template<int N>
+struct multiboot2
+{
+    static constexpr std::uint32_t MAGIC    = 0xE85250D6;
+    static constexpr std::uint32_t FLAGS    = 0;
+    static constexpr std::uint32_t LENGTH   = 16;
+    static constexpr std::uint32_t CHECKSUM = -(MAGIC + FLAGS + LENGTH);
+
+    alignas(8)
+    std::uint32_t magic = MAGIC;
+    std::uint32_t flags = FLAGS;
+    std::uint32_t length = LENGTH;
+    std::uint32_t checksum = CHECKSUM;
+
+    multiboot2_tag tags[N];
+} __attribute__((packed));
+
+__attribute__((section(".multiboot2")))
+multiboot2 multibootHeader = {
+    .tags = {
+        {
+            1, 0, sizeof(multiboot2_tag) + sizeof(std::uint32_t),
+            {4}
+        },
+        {
+            0, 0, 8, {}
+        }
+    }
+};
+
+std::uint32_t multiboot_magic;
+std::uint32_t *multiboot_ptr;
+
+std::uint32_t lowerMem = 0;
+std::uint32_t upperMem = 0;
+std::uint32_t *acpiRsdp = nullptr;
+std::uint32_t *acpiRsdpV2 = nullptr;
+
+bool multiboot_initialize()
+{
+    if (multiboot_magic != 0x36d76289) {
+        term.write("Not multiboot!");
+        return false;
+    }
+
+    term.write("Found multiboot headers: ");
+
+    auto ptr = multiboot_ptr + 2;
+    while (ptr[0] != 0 && ptr[1] != 8) {
+        term.write(ptr[0]);
+        term.write(", ");
+
+        switch (ptr[0]) {
+        case 4:
+            lowerMem = ptr[2] * 1024;
+            upperMem = ptr[3] * 1024;
+            break;
+        case 14:
+            acpiRsdp = ptr + 2;
+            break;
+        case 15:
+            acpiRsdpV2 = ptr + 2;
+            break;
+        default:
+            break;
+        }
+    
+        auto next = reinterpret_cast<std::uintptr_t>(ptr);
+        next += ptr[1];
+        next = (next + 7) & ~7;
+        ptr = reinterpret_cast<std::uint32_t *>(next);
+    }
+
+    term.write('\n');
+    return true;
+}
+