Add base address calculation

src/rvprof_symbols.c

@@ -0,0 +1,28 @@
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <elf.h>
+#include <ctype.h>
+#include "rvprof_internal.h"
+
+// thread-local storage for function names
+__thread char g_tmp_func_name[128];
+
+// base offset for PIE
+static uintptr_t g_base_address_offset = 0;
+static int g_base_address_calculated = 0;
+
+
+// base address calculatiion
+static void calculate_base_address(void* known_runtime_addr, uintptr_t known_elf_addr){
+    if (g_base_address_calculated) return;
+
+    uintptr_t runtime_addr = (uintptr_t)known_runtime_addr;
+    if (runtime_addr > known_elf_addr){
+        g_base_address_offset = runtime_addr - known_elf_addr;
+    }
+    g_base_address_calculated = 1;
+}
+
+// compare function for symbol table quicksort
+// TODO