Added memory arena

Fixed frames in flight validation error in vulkan
Added some utility macros
Added function decorator macros
Added some consolidation headers/code include files

code/os/core.c

@@ -0,0 +1,3 @@
+#if OS_WINDOWS
+	#include "impl/windows/core.c"
+#endif

code/os/core.h

@@ -0,0 +1,14 @@
+#if !defined(LD_OS_CORE_H_)
+#define LD_OS_CORE_H_
+
+// Virtual memory
+
+function U64 VM_PageSize();
+function U64 VM_AllocationGranularity();
+
+function void *VM_Reserve(U64 size);
+function B32   VM_Commit(void *base, U64 size);
+function void  VM_Decommit(void *base, U64 size);
+function void  VM_Release(void *base, U64 size);
+
+#endif  // LD_OS_CORE_H_

code/os/impl/windows/core.c

@@ -0,0 +1,38 @@
+// Virtual memory
+
+U64 VM_PageSize() {
+	SYSTEM_INFO info;
+	GetSystemInfo(&info);
+
+	U64 result = info.dwPageSize;
+	return result;
+}
+
+U64 VM_AllocationGranularity() {
+	SYSTEM_INFO info;
+	GetSystemInfo(&info);
+
+	U64 result = info.dwAllocationGranularity;
+	return result;
+}
+
+void *VM_Reserve(U64 size) {
+	void *result = VirtualAlloc(0, size, MEM_RESERVE, PAGE_NOACCESS);
+	return result;
+}
+
+B32 VM_Commit(void *base, U64 size) {
+	B32 result = VirtualAlloc(base, size, MEM_COMMIT, PAGE_READWRITE) != 0;
+	return result;
+}
+
+void VM_Decommit(void *base, U64 size) {
+	VirtualFree(base, size, MEM_DECOMMIT);
+}
+
+void VM_Release(void *base, U64 size) {
+	(void) size;
+
+	VirtualFree(base, 0, MEM_RELEASE);
+}
+