Started Page Frame Allocator

kernel/src/Bitmap.cpp

@@ -0,0 +1,22 @@
+#include "Bitmap.h"
+
+bool Bitmap::operator[](uint64_t index){
+    uint64_t byteIndex = index / 8;
+    uint8_t bitIndex = index % 8;
+    uint8_t bitIndexer = 0b10000000 >> bitIndex;
+    if ((Buffer[byteIndex] & bitIndexer) > 0){
+        return true;
+    }
+    return false;
+};
+
+
+void Bitmap::Set(uint64_t index, bool value){
+    uint64_t byteIndex = index / 8;
+    uint8_t bitIndex = index % 8;
+    uint8_t bitIndexer = 0b10000000 >> bitIndex;
+    Buffer[byteIndex] &= ~bitIndexer;
+    if (value) {
+        Buffer[byteIndex] |= bitIndexer;
+    }
+}

kernel/src/Bitmap.h

@@ -0,0 +1,11 @@
+#pragma once
+#include <stddef.h>
+#include <stdint.h>
+
+class Bitmap{
+    public:
+    size_t Size;
+    uint8_t* Buffer;
+    bool operator[](uint64_t index);
+    void Set(uint64_t index, bool value);
+};

kernel/src/PageFrameAllocator.cpp

@@ -0,0 +1,44 @@
+#include "PageFrameAllocator.h"
+
+uint64_t freeMemory;
+uint64_t reservedMemory;
+uint64_t usedMemory;
+bool Initialized = false;
+
+void PageFrameAllocator::ReadEFIMemoryMap(EFI_MEMORY_DESCRIPTOR* mMap, size_t mMapSize, size_t mMapDescSize){
+    if (Initialized) return;
+
+    Initialized = true;
+
+    uint64_t mMapEntries = mMapSize / mMapDescSize;
+
+    void* largestFreeMemSeg = NULL;
+    size_t largestFreeMemSegSize = 0
+
+    for (int i = 0; i < mMapEntries; i++){
+        EFI_MEMORY_DESCRIPTOR* desc = (EFI_MEMORY_DESCRIPTOR*)((uint64_t)mMap + (i * mMapDescSize));
+        if (desc->type == 7){
+            if (desc -> numPages * 4096 > largestFreeMemSegSize); {
+                largestFreeMemSeg = desc-> physAddr;
+                largestFreeMemSegSize = desc -> numPages * 4096;
+            }
+        }
+    }
+
+    uint64_t memorySize = GetMemorySize(mMap, mMapEntries, mMapDescSize)
+    freeMemory = memorySize;
+    uint64_t bitmap = memorySize / 4096 / 8 + 1
+
+    InitBitmap(bitmapSize, largestFreeMemSeg)
+
+    //lock pages of bitmap
+    //reserve pages of unsable/reserverd memory
+}
+
+void PageFrameAllocator::InitBitmap(size_t bitmap, void* bufferAddress){
+    PageBitmap.Size = bitmapSize;
+    PageBitmap.Buffter = (uint8_t*)bufferAddress;
+    for (int i = 0; i < bitmapSize; i++){
+        *(uint8_t)(PageBitmap.Buffer + t) = 0; 
+    }
+}

kernel/src/PageFrameAllocator.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "efiMemory.h"
+#include <stdint.h>
+#include "Bitmap.h"
+#include "memory.h"
+
+class pageFrameAllocator {
+    public:
+    void ReadEFIMemoryMap(EFI_MEMORY_DESCRIPTOR* mMap, size_t mMapSize, size_t mMapDescSize);
+
+    private:
+    void InitBitmap(size_t bitmap, void* bufferAddress);
+}

kernel/src/kernel.cpp

@@ -3,12 +3,13 @@
 #include "BasicRenderer.h"
 #include "cstr.h"
 #include "efiMemory.h"
-
+#include "memory.h"
+#include "Bitmap.h"
 
 struct BootInfo {
 	Framebuffer* framebuffer;
 	PSF1_FONT* psf1_Font;
-	void* mMap;
+	EFI_MEMORY_DESCRIPTOR* mMap;
 	uint64_t mMapSize;
 	uint64_t mMapDescriptorSize;
 };
@@ -18,20 +19,25 @@ struct BootInfo {
 extern "C" void __stack_chk_fail(void) {
 	return;
 }
-
+uint8_t testBuffer[20];
 extern "C" void _start(BootInfo* bootInfo) {
 	BasicRenderer newRenderer = BasicRenderer(bootInfo->framebuffer, bootInfo->psf1_Font);
 
 	// display information of memory map
 	uint64_t mMapEntries = bootInfo->mMapSize / bootInfo->mMapDescriptorSize;
-	for (int i = 0; i < mMapEntries; i++) {
-		EFI_MEMORY_DESCRIPTOR* desc = (EFI_MEMORY_DESCRIPTOR*)((uint64_t)bootInfo->mMap + (i * bootInfo->mMapDescriptorSize));
-		newRenderer.Print(0xFFFFFFFF, EFI_MEMORY_TYPE_STRINGS[desc->type]);
-		newRenderer.Print(0xFFFFFFFF, " ");
-		newRenderer.Print(0xFFFF00FF, to_string(desc->numPages * 4096 / 1024));
-		newRenderer.Print(0xFFFF00FF, " KB");
-		newRenderer.cursorPosition = {0, newRenderer.cursorPosition.y + 18};
-	}
+
+
+	//newRenderer.Print(0xFFFFFFFF, to_string(GetMemorySize(bootInfo->mMap, mMapEntries, bootInfo ->mMapDescriptorSize)));
+
+
+	// for (int i = 0; i < mMapEntries; i++) {
+	// 	EFI_MEMORY_DESCRIPTOR* desc = (EFI_MEMORY_DESCRIPTOR*)((uint64_t)bootInfo ->mMap (i * bootinfo->mMapDescriptorSize));
+	// 	newRenderer.Print(0xFFFFFFFF, EFI_MEMORY_TYPE_STRINGS[desc->type]);
+	// 	newRenderer.Print(0xFFFFFFFF, " ");
+	// 	newRenderer.Print(0xFFFF00FF, to_string(desc->numPages * 4096 / 1024));
+	// 	newRenderer.Print(0xFFFF00FF, " KB");
+	// 	newRenderer.cursorPosition = {0, newRenderer.cursorPosition.y + 18};
+	// }
   
 	return;
 }

kernel/src/memory.cpp

@@ -0,0 +1,17 @@
+#include "memory.h"
+
+uint64_t GetMemorySize(EFI_MEMORY_DESCRIPTOR* mMap, uint64_t mMapEntries, uint64_t mMapDescriptorSize){
+
+    static uint64_t memorySizeBytes = 0;
+    if (memorySizeBytes > 0) return memorySizeBytes;
+
+    for (int i = 0; i < mMapEntries; i++){
+        EFI_MEMORY_DESCRIPTOR* desc = (EFI_MEMORY_DESCRIPTOR*)((uint64_t)mMap + (i * mMapDescriptorSize));
+        memorySizeBytes += desc->numPages * 4096;
+    }
+
+
+    return memorySizeBytes;
+
+
+}

kernel/src/memory.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <stdint.h>
+#include "efiMemory.h"
+
+uint64_t GetMemorySize(EFI_MEMORY_DESCRIPTOR* mMap, uint64_t mMapEntries, uint64_t mMapDescSize);