From 9654487b5b6f5402f1350d3fe75ad35d722a85ef Mon Sep 17 00:00:00 2001
From: pjht <terppa05@gmail.com>
Date: Tue, 28 May 2019 16:05:51 -0500
Subject: [PATCH] add unmap_pages

---
 kernel/cpu/i386/paging.c | 16 ++++++++++++++++
 kernel/cpu/i386/paging.h |  1 +
 2 files changed, 17 insertions(+)

diff --git a/kernel/cpu/i386/paging.c b/kernel/cpu/i386/paging.c
index 80c9f82..d0331a1 100644
--- a/kernel/cpu/i386/paging.c
+++ b/kernel/cpu/i386/paging.c
@@ -153,6 +153,22 @@ void load_smap(uint32_t cr3) {
   }
 }
 
+void unmap_pages(void* start_virt,uint32_t num_pages) {
+  uint32_t virt_addr=(uint32_t)start_virt;
+  int dir_entry=(virt_addr&0xFFC00000)>>22;
+  int table_entry=(virt_addr&0x3FF000)>>12;
+  for (int i=0;i<=num_pages;i++) {
+    if (smap[dir_entry]&0x1) {
+      smap_page_tables[dir_entry+1]=(smap[dir_entry]&0xFFFFFC00)|0x3;
+      smap[(1024+(1024*dir_entry))+table_entry]=0;
+      table_entry++;
+      if (table_entry==1024) {
+        dir_entry++;
+        table_entry=0;
+      }
+    }
+  }
+}
 
 void paging_init() {
   for (uint32_t i=0;i<NUM_KERN_DIRS*1024;i++) {
diff --git a/kernel/cpu/i386/paging.h b/kernel/cpu/i386/paging.h
index 655f951..790a3a3 100644
--- a/kernel/cpu/i386/paging.h
+++ b/kernel/cpu/i386/paging.h
@@ -7,6 +7,7 @@
 #define NUM_KERN_DIRS 1
 
 void map_pages(void* virt_addr_ptr,void* phys_addr_ptr,int num_pages,char usr,char wr);
+void unmap_pages(void* start_virt,uint32_t num_pages);
 void* alloc_pages(int num_pages);
 void alloc_pages_virt(int num_pages,void* addr);
 void paging_init();