1 files changed, 67 insertions, 0 deletions
diff --git a/src/kernel/paging/paging.c b/src/kernel/paging/paging.c
new file mode 100644
index 0000000..6a482c8
--- /dev/null
+++ b/src/kernel/paging/paging.c
@@ -0,0 +1,67 @@
+#include "paging.h"
+#include "exceptions.h"
+#include <stdint.h>
+extern uint32_t endkernel;
+
+Page_Directory make_pagedir(Page_Table *addr, uint8_t flags) {
+    return ((uint32_t)addr & 0xFFFFF000) | flags;
+}
+
+Page_Table make_pagetable(uint32_t addr, uint8_t flags) {
+    return ((uint32_t)addr & 0xFFFFF000) | flags;
+}
+
+Page_Directory page_dir[1024] __attribute__((aligned(4096)));
+Page_Table pgtable[1024] __attribute__((aligned(4096)));
+
+void idpaging(uint32_t *first_pte, uint32_t from, int size) {
+    for (; size > 0; from += 4096, size -= 4096, first_pte++) {
+        *first_pte = make_pagetable(from, 3); // mark page present.
+    }
+}
+
+void genDirs() {
+    for (int i = 0; i < 1024; i++) {
+        page_dir[i] = make_pagedir(0x0, 2);
+        for (int j = 0; j < 1024; j++)
+            ((uint32_t *)(page_dir[i] & 0xFFFFF000))[j] &= 0xFFFFFFFE;
+    }
+
+    page_dir[1023] = make_pagetable((uint32_t)page_dir, 3);
+
+    idpaging(&pgtable[0], 0x0, 1024 * 0x800);
+    page_dir[0] = make_pagedir(pgtable, 3);
+}
+
+void *get_physaddr(void *virtualaddr) {
+    unsigned long pdindex = (unsigned long)virtualaddr >> 22;
+    unsigned long ptindex = (unsigned long)virtualaddr >> 12 & 0x03FF;
+
+    unsigned long *pd = (unsigned long *)page_dir;
+    if (!(pd[pdindex] & 1))
+        panic("Unimplemented - getphysaddr - pd[%d]", pdindex);
+
+    unsigned long *pt = ((unsigned long *)0xFFC00000) + (0x400 * pdindex);
+    if (!(pt[ptindex] & 1))
+        panic("Unimplemented - getphysaddr - pt[%d]", ptindex);
+
+    return (void *)((pt[ptindex] & ~0xFFF) +
+                    ((unsigned long)virtualaddr & 0xFFF));
+}
+
+void map_page(void *physaddr, void *virtualaddr, uint8_t flags) {
+    unsigned long pdindex = (unsigned long)virtualaddr >> 22;
+    unsigned long ptindex = (unsigned long)virtualaddr >> 12 & 0x03FF;
+
+    unsigned long *pd = (unsigned long *)page_dir;
+    if (!(pd[pdindex] & 1)) {
+        pd[pdindex] =
+            make_pagedir((uint32_t *)0xFFC00000 + (0x400 * pdindex), 3);
+    }
+
+    unsigned long *pt = ((unsigned long *)0xFFC00000) + (0x400 * pdindex);
+    if (pt[ptindex] & 1)
+        panic("Unimplemented - map_page - pt[%d]", ptindex);
+
+    pt[ptindex] = ((unsigned long)physaddr) | (flags & 0xFFF) | 0x01; // Present
+}