Added crc32builder

CMakeLists.txt

@@ -1,5 +1,6 @@
 set(headers
     src/cleanuphelper.h
+    src/crc32builder.h
     src/cppflags.h
     src/cppmacros.h
     src/cppoverloadutils.h

src/crc32builder.h

@@ -0,0 +1,38 @@
+#pragma once
+
+namespace cpputils {
+
+class Crc32Builder
+{
+public:
+    std::size_t write(uint8_t c)
+    {
+        return write(&c, 1);
+    }
+
+    std::size_t write(const uint8_t *buf, std::size_t len)
+    {
+        auto lenTemp = len;
+        while (lenTemp--)
+        {
+            uint32_t val = (crc ^ * buf++) & 0xFF;
+            for (uint8_t i = 0; i < 8; i++)
+            {
+                val = val & 1 ? (val>>1)^0xEDB88320 : val>>1;
+            }
+            crc = val^crc>>8;
+        }
+
+        return len;
+    };
+
+    uint32_t hash() const
+    {
+        return crc ^ 0xFFFFFFFF;
+    }
+
+private:
+    uint32_t crc{0xFFFFFFFF};
+};
+
+} // namespace cpputils