From 93b11307fa90a704d46a22129dce49dca258ff40 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 13 Apr 2016 00:21:28 -0400
Subject: [PATCH] Add memory::pageAlignUp/Down functions

---
 src/memory/Memory.cc |  7 +++++++
 src/memory/Memory.hh | 24 ++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/memory/Memory.cc b/src/memory/Memory.cc
index b924cd8..1513ba9 100644
--- a/src/memory/Memory.cc
+++ b/src/memory/Memory.cc
@@ -41,4 +41,11 @@ MemoryManager::initializeGDT()
     kstd::printFormat("GDT loaded\n");
 }
 
+namespace memory {
+
+const u32 pageSize = 4096;
+const u32 pageMask = pageSize - 1;
+
+} /* namespace memory */
+
 } /* namespace kernel */
diff --git a/src/memory/Memory.hh b/src/memory/Memory.hh
index b5fb4c5..f012f67 100644
--- a/src/memory/Memory.hh
+++ b/src/memory/Memory.hh
@@ -30,6 +30,30 @@ private:
     void initializeGDT();
 };
 
+namespace memory {
+
+extern const u32 pageSize;
+extern const u32 pageMask;
+
+/** Align to the nearest page boundary below `addr`. */
+inline u32
+pageAlignDown(u32 addr)
+{
+    return addr & ~pageMask;
+}
+
+/** Align to the nearest page boundary above `addr`. */
+inline u32
+pageAlignUp(u32 addr)
+{
+    if (pageAlignDown(addr) == addr) {
+        return addr;
+    }
+    return (addr + pageSize) & ~pageMask;
+}
+
+} /* namespace memory */
+
 } /* namespace kernel */
 
 #endif /* __MEMORY_MEMORY_HH__ */