1 files changed, 55 insertions, 0 deletions
diff --git a/kernel/mm/pmm.cpp b/kernel/mm/pmm.cpp
new file mode 100644
index 0000000..bd8f12c
--- /dev/null
+++ b/kernel/mm/pmm.cpp
@@ -0,0 +1,55 @@
+#include <mm/pmm.h>
+#include <stdio.h>
+
+PBitmap bitmap;
+
+// Finds the biggest chunk of memory
+static MMEntry find_mem_chunk(limine_memmap_response* memmap) {
+    uint64_t highestmem = 0;
+    size_t highestindex = 0;
+    limine_memmap_entry* entries = memmap->entries[0];
+    for (size_t i = 0; i < memmap->entry_count; i++) {
+        if (entries[i].type == LIMINE_MEMMAP_USABLE && entries[i].length > highestmem) {
+            highestmem = entries[i].length;
+            highestindex = i;
+        }
+    }
+
+    return MMEntry{
+        entries[highestindex].base,
+        entries[highestindex].length,
+        MEM_USABLE
+    };
+}
+
+void pmm_init(limine_memmap_response* memmap, uint64_t hhdm_offset) {
+    MMEntry mem_entry = find_mem_chunk(memmap);
+
+    // Round any numbers needed to 4K boudaries
+    //mem_entry.base += 4096 - (mem_entry.base % 4096);
+    mem_entry.length -= mem_entry.length % 4096;
+
+    // setup bitmap at the beginning of the chunk
+    bitmap.entry = mem_entry;
+    bitmap.addr = (uint64_t*)(bitmap.entry.base + hhdm_offset);
+    // divided by byte size since size is for iterating over the bitmap
+    bitmap.size = mem_entry.length / 4096 / sizeof(uint64_t);
+
+    printf("addr: %lx\nsize: %lx\n", (uint64_t)bitmap.addr, bitmap.size);
+    printf("hhdm offset: %lx\n", hhdm_offset);
+
+    // write test
+    for (size_t i = 0; i < 100; i++) {
+        bitmap.addr[i] = i;
+        //printf("value %d: %lx\n", i, bitmap.addr[i]);
+    }
+
+    // read test
+    for (size_t i = 0; i < bitmap.size; i++) {
+        //printf("value %d: %lx\n");
+    }
+}
+
+uint64_t get_phys_page() {
+
+}
+\ No newline at end of file