From 2072c8fe534cfad47953ff4886d4a6078a3e6a79 Mon Sep 17 00:00:00 2001
From: Tom-on64 <kubecekt@gmail.com>
Date: Thu, 23 May 2024 17:26:56 +0200
Subject: [PATCH] Began work in Virtual Memory Manager!

---
 include/memory/virtual.h | 54 ++++++++++++++++++++++++++++++++++++++++
 src/kernel.c             |  2 ++
 2 files changed, 56 insertions(+)
 create mode 100644 include/memory/virtual.h

diff --git a/include/memory/virtual.h b/include/memory/virtual.h
new file mode 100644
index 0000000..9cda24c
--- /dev/null
+++ b/include/memory/virtual.h
@@ -0,0 +1,54 @@
+#ifndef VIRTUAL_H
+#define VIRTUAL_H
+
+#include <stdint.h>
+#include <memory/physical.h>
+
+#define PAGES_PER_TABLE 1024
+#define TABLES_PER_DIRECTORY 1024
+#define PAGE_SIZE 4096
+
+#define PD_INDEX(_vAddress) ((_vAddress) >> 22)
+#define PT_INDEX(_vAddress) (((_vAddress) >> 12) & 0x3ff)
+
+typedef uint32_t ptEntry_t;
+typedef uint32_t pdEntry_t;
+
+typedef enum {
+    PTE_PRESENT         = 0x01,
+    PTE_READ_WRITE      = 0x02,
+    PTE_USER            = 0x04,
+    PTE_WRITE_THROUGH   = 0x08,
+    PTE_CACHE_DISABLE   = 0x10,
+    PTE_ACCESSED        = 0x20,
+    PTE_DIRTY           = 0x40,
+    PTE_PAT             = 0x80,
+    PTE_GLOBAL          = 0x100,
+    PTE_FRAME           = 0x7ffff000,
+} PAGE_TABLE_FLAGS;
+
+typedef enum {
+    PDE_PRESENT         = 0x01,
+    PDE_READ_WRITE      = 0x02,
+    PDE_USER            = 0x04,
+    PDE_WRITE_THROUGH   = 0x08,
+    PDE_CACHE_DISABLE   = 0x10,
+    PDE_ACCESSED        = 0x20,
+    PDE_DIRTY           = 0x40, // Only with 4MB pages
+    PDE_PAGE_SIZE       = 0x80, // Is page 4MB
+    PDE_GLOBAL          = 0x100,
+    PDE_PAT             = 0x2000,
+    PDE_FRAME           = 0x7ffff000,
+} PAGE_DIR_FLAGS;
+
+typedef struct {
+    ptEntry_t entries[PAGES_PER_TABLE];
+} pageTable_t;
+
+typedef struct {
+    pdEntry_t entries[TABLES_PER_DIRECTORY];
+} pageDirectory_t;
+
+pageDirectory_t* currentPd = 0;
+
+#endif
diff --git a/src/kernel.c b/src/kernel.c
index 76e5697..0e98048 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -14,6 +14,7 @@
 #include <time.h>
 #include <sound/pcspk.h>
 #include <sound/notes.h>
+#include <memory/virtual.h>
 
 #define PROMPT "#> "
 
@@ -222,6 +223,7 @@ void main() {
                 playNote(F4,  120);
                 playNote(G4,  120);
             }
+            rest(120);
 
             disableSpeaker();
         } else if (strcmp(input, "test") == 0) {