Added very simple kernel memory allocator

src/Makefile.am

@@ -1,5 +1,5 @@
 noinst_PROGRAMS = quark-kernel
-quark_kernel_SOURCES = kernel.c memorymap.c pageallocator.c priorityqueue.c stdio.c string.c elf.c resource.c
+quark_kernel_SOURCES = kernel.c memorymap.c pageallocator.c priorityqueue.c stdio.c string.c elf.c resource.c allocator.c
 quark_kernel_LDADD = -lgcc
 quark_kernel_CFLAGS = -I$(top_srcdir)/include -ffreestanding -mgeneral-regs-only -O0 -Wall -ggdb
 quark_kernel_LDFLAGS = -nostdlib

src/allocator.c

@@ -0,0 +1,34 @@
+#include "allocator.h"
+
+struct linear_allocator_t
+{
+    void *bottom;
+    void *top;
+} allocator;
+
+void initialize_allocator(void *bottom, void *top)
+{
+    allocator.bottom = bottom;
+    allocator.top = top;
+}
+
+void *allocate_from_bottom(size_t size)
+{
+    if((size_t)allocator.bottom + size <= (size_t)allocator.top)
+    {
+        void *ptr = allocator.bottom;
+        allocator.bottom += size;
+        return ptr;
+    }
+    return (void*)NULL;
+}
+
+void *allocate_from_top(size_t size)
+{
+    if((size_t)allocator.top - size >= (size_t)allocator.bottom)
+    {
+        allocator.top -= size;
+        return allocator.top;
+    }
+    return (void*)NULL;
+}