Amalgamate FileIO and remove duplicate Timer header

Closes #8

common/util/FileUtil.cpp

@@ -108,3 +108,46 @@ std::string file_util::read_text_file(const std::string& path) {
 bool file_util::is_printable_char(char c) {
   return c >= ' ' && c <= '~';
 }
+
+std::string file_util::combine_path(const std::string& parent, const std::string& child) {
+  return parent + "/" + child;
+}
+
+std::string file_util::base_name(const std::string& filename) {
+  size_t pos = 0;
+  assert(!filename.empty());
+  for (size_t i = filename.size() - 1; i-- > 0;) {
+    if (filename.at(i) == '/') {
+      pos = (i + 1);
+      break;
+    }
+  }
+
+  return filename.substr(pos);
+}
+
+static bool sInitCrc = false;
+static uint32_t crc_table[0x100];
+
+void file_util::init_crc() {
+  for (uint32_t i = 0; i < 0x100; i++) {
+    uint32_t n = i << 24u;
+    for (uint32_t j = 0; j < 8; j++)
+      n = n & 0x80000000 ? (n << 1u) ^ 0x04c11db7u : (n << 1u);
+    crc_table[i] = n;
+  }
+  sInitCrc = true;
+}
+
+uint32_t file_util::crc32(const uint8_t* data, size_t size) {
+  assert(sInitCrc);
+  uint32_t crc = 0;
+  for (size_t i = size; i != 0; i--, data++) {
+    crc = crc_table[crc >> 24u] ^ ((crc << 8u) | *data);
+  }
+  return ~crc;
+}
+
+uint32_t file_util::crc32(const std::vector<uint8_t>& data) {
+  return crc32(data.data(), data.size());
+}