CTAOS v4

SysCore/memory/mmngr_vi.c

@@ -0,0 +1,140 @@
+// +==============================================+
+// |    HEADERS                                   |
+// +===================================== cta os =+
+#include "mmngr_vi.h"
+#include "mmngr_ph.h"
+
+// +==============================================+
+// |    DEFINITIONS                               |
+// +===================================== cta os =+
+#define PAGE_SIZE 4096
+#define PTABLE_ADDR_SPACE_SIZE 0x400000
+#define DTABLE_ADDR_SPACE_SIZE 0xffffffff
+
+pdirectory* _current_directory;
+unsigned _current_page_directory_base_register;
+extern unsigned char *memset (unsigned char *dest, unsigned char val, int count);
+extern char getch();
+
+// +==============================================+
+// |    PAGE FUNCTIONS                            |
+// +===================================== cta os =+
+unsigned char vmmngr_alloc_page (pt_entry* entry)
+{
+      void* p = pmmngr_alloc_block ();
+      if (!p) return 0;
+      
+      pt_entry_set_frame(entry, (unsigned)p);
+      pt_entry_add_attrib (entry, _I86_PTE_PRESENT);
+      
+      return 1;
+}
+
+void vmmngr_free_page (pt_entry* entry)
+{
+      void* p = (void*) pt_entry_get_frame(*entry);
+      
+      if (p) pmmngr_free_block (p);
+      
+      pt_entry_del_attrib (entry, _I86_PTE_PRESENT);
+}
+
+
+// +==============================================+
+// |    PAGE TABLE FUNCTIONS                      |
+// +===================================== cta os =+
+inline void vmmngr_ptable_clear(ptable* p)
+{
+      if(p) memset ((unsigned char*)p, 0, sizeof(ptable));
+}
+
+inline unsigned vmmngr_ptable_virt_to_index (unsigned addr)
+{
+      return (addr >= PTABLE_ADDR_SPACE_SIZE) ? 0 : addr/PAGE_SIZE;
+}
+
+inline pt_entry* vmmngr_ptable_lookup_entry (ptable* p, unsigned addr)
+{
+      if (p) return &p->m_entries[vmmngr_ptable_virt_to_index(addr)];
+      return 0;
+}
+
+
+// +==============================================+
+// |    PAGE DIRECTORY FUNCTIONS                  |
+// +===================================== cta os =+
+inline void vmmngr_pdirectory_clear(pdirectory* dir)
+{
+      if(dir) memset ((unsigned char*)dir, 0, sizeof(pdirectory));
+}
+
+inline unsigned vmmngr_pdirectory_virt_to_index (unsigned addr)
+{
+      return (addr > DTABLE_ADDR_SPACE_SIZE) ? 0 : addr/PAGE_SIZE;
+}
+
+inline pd_entry* vmmngr_pdirectory_lookup_entry (pdirectory* dir, unsigned addr)
+{
+      if (dir) return &dir->m_entries[vmmngr_ptable_virt_to_index(addr)];
+      return 0;
+}
+
+// +==============================================+
+// |    VIRTUAL MEMORY MANAGER                    |
+// +===================================== cta os =+
+inline unsigned char vmmngr_switch_pdirectory (pdirectory* dir)
+{
+      if (!dir) return 0;
+      _current_directory = dir;
+      
+      write_cr3 (_current_page_directory_base_register);
+      return 1;
+}
+
+pdirectory* vmmngr_get_directory() {
+    return _current_directory;
+}
+
+void vmmngr_initialize()
+{
+      // Allocate default page table
+      ptable* table = (ptable*) pmmngr_alloc_block();
+      if (!table) return;
+      
+      // Clear page table
+      vmmngr_ptable_clear(table);
+      
+      // Identity map the first page table
+      int i, frame;
+      for (i = 0, frame = 0; i < 1024; i++, frame += 4096)
+      {
+            // Create a new page
+            pt_entry page = 0;
+            pt_entry_add_attrib (&page, _I86_PTE_PRESENT);
+            pt_entry_set_frame (&page, frame);
+            
+            table->m_entries[vmmngr_ptable_virt_to_index(frame)] = page;
+      }
+
+      // Create default directory table
+      pdirectory* dir = (pdirectory*) pmmngr_alloc_blocks(3);
+      if (!dir) return;
+
+      // Clear directory table and set it as current
+      vmmngr_pdirectory_clear(dir);
+
+      // Get first entry in dir table and set it up to point to our table
+      pd_entry* entry = vmmngr_pdirectory_lookup_entry(dir, 0);
+      pd_entry_add_attrib (entry, _I86_PDE_PRESENT);
+      pd_entry_add_attrib (entry, _I86_PDE_WRITABLE);
+      pd_entry_set_frame (entry, (unsigned) table);
+ 
+      // Store current PDBR
+      _current_page_directory_base_register = (unsigned) &dir->m_entries;
+
+      // Switch to our page directory
+      vmmngr_switch_pdirectory (dir);
+      
+      // Enable paging
+      pmmngr_paging_enable (1);
+}