Initialize the frame allocator

Does not actually do anything yet...

src/Kernel.cc

@@ -66,7 +66,7 @@ Kernel::initialize(const StartupInformation& startupInformation)
                           (*it).type == 1 ? "available" : "reserved");
     }
 
-    mMemoryManager.initialize();
+    mMemoryManager.initialize(startupInformation);
 }
 
 

src/SConscript

@@ -24,6 +24,7 @@ files = [
     'kstd/Memory.cc',
     'kstd/PrintFormat.cc',
 
+    'memory/FrameAllocator.cc',
     'memory/Memory.cc',
 ]
 

src/memory/FrameAllocator.cc

@@ -6,10 +6,33 @@
  * An object to tracks and allocate physical page frames.
  */
 
-#include "FrameAllocator.hh"
+#include "Kernel.hh"
+#include "kstd/Memory.hh"
+#include "kstd/PrintFormat.hh"
+#include "memory/FrameAllocator.hh"
 
 namespace kernel {
 
+FrameAllocator::FrameAllocator()
+    : mBitmap(nullptr),
+      mBitmapSize(0)
+{ }
+
+
+void
+FrameAllocator::initialize(const StartupInformation& startupInformation)
+{
+    // Page frame bitmap starts immediately after the kernel.
+    mBitmap = reinterpret_cast<u8*>(startupInformation.kernelEnd);
+
+    const u32 pageSize = startupInformation.pageSize;
+    const u32 numberOfPages = startupInformation.multibootInformation->memoryKB() * 1024 / pageSize;
+    mBitmapSize = numberOfPages / (sizeof(FrameBitmap) * 8);
+
+    kstd::printFormat("Allocated bitmap of %ld bytes for %ld pages at 0x%08lX\n", mBitmapSize, numberOfPages, u32(mBitmap));
+
+    // TODO: Before modifying this memory, maybe make sure none of the multiboot information is hanging out there?
+    kstd::Memory::zero(mBitmap, mBitmapSize);
+}
 
-    
 } /* namespace kernel */

src/memory/FrameAllocator.hh

@@ -9,10 +9,25 @@
 #ifndef __MEMORY_FRAMEALLOCATOR_HH__
 #define __MEMORY_FRAMEALLOCATOR_HH__
 
+#include "StartupInformation.hh"
+#include "kstd/Types.hh"
+
+
 namespace kernel {
 
 struct FrameAllocator
 {
+    FrameAllocator();
+
+    void initialize(const StartupInformation& startupInformation);
+
+private:
+    typedef u8 FrameBitmap;
+
+    /** Starting address of the frame allocation bitmap. */
+    FrameBitmap* mBitmap;
+    /** Size of the bitmap in bytes. */
+    u32 mBitmapSize;
 };
 
 } /* namespace  */

src/memory/Memory.cc

@@ -6,8 +6,8 @@
  * Top-level classes for managing system memory.
  */
 
-#include "Memory.hh"
 #include "kstd/PrintFormat.hh"
+#include "memory/Memory.hh"
 
 namespace kernel {
 
@@ -15,11 +15,16 @@ namespace kernel {
  * Public
  */
 
+MemoryManager::MemoryManager()
+    : mGDT(),
+      mFrameAllocator()
+{ }
+
 void
-MemoryManager::initialize()
+MemoryManager::initialize(const StartupInformation& startupInformation)
 {
     initializeGDT();
-    kstd::printFormat("GDT loaded\n");
+    mFrameAllocator.initialize(startupInformation);
 }
 
 /*
@@ -33,6 +38,7 @@ MemoryManager::initializeGDT()
     mGDT.setDescriptor(1, x86::GDT::DescriptorSpec::kernelSegment(0, 0xFFFFFFFF, x86::GDT::Type::CodeEXR));
     mGDT.setDescriptor(2, x86::GDT::DescriptorSpec::kernelSegment(0, 0xFFFFFFFF, x86::GDT::Type::DataRW));
     mGDT.load();
+    kstd::printFormat("GDT loaded\n");
 }
 
 } /* namespace kernel */

src/memory/Memory.hh

@@ -6,25 +6,30 @@
  * Declaration of top-level classes for managing system memory.
  */
 
-#ifndef __MEMORY_HH__
+#ifndef __MEMORY_MEMORY_HH__
-#define __MEMORY_HH__
+#define __MEMORY_MEMORY_HH__
 
 #include "Console.hh"
 #include "Descriptors.hh"
+#include "StartupInformation.hh"
+#include "memory/FrameAllocator.hh"
 
 
 namespace kernel {
 
 struct MemoryManager
 {
-    void initialize();
+    MemoryManager();
+
+    void initialize(const StartupInformation& startupInformation);
 
 private:
     x86::GDT mGDT;
+    kernel::FrameAllocator mFrameAllocator;
 
     void initializeGDT();
 };
 
 } /* namespace kernel */
 
-#endif /* __MEMORY_HH__ */
+#endif /* __MEMORY_MEMORY_HH__ */