split adler32 code from hash.c to independent program

hash/hash_adler32.c

@@ -0,0 +1,54 @@
+/**
+ * @addtogroup hash Hash algorithms
+ * @{
+ * @file hash_adler32.c
+ * @author [Christian Bender](https://github.com/christianbender)
+ * @author [Krishna Vedala](https://github.com/kvedala)
+ * @brief 32-bit [Adler hash](https://en.wikipedia.org/wiki/Adler-32) algorithm
+ */
+#include <assert.h>
+#include <inttypes.h>
+#include <stdio.h>
+
+/**
+ * @brief 32-bit Adler algorithm implementation
+ *
+ * @param s NULL terminated ASCII string to hash
+ * @return 32-bit hash result
+ */
+uint32_t adler32(const char* s)
+{
+    uint32_t a = 1;
+    uint32_t b = 0;
+    const uint32_t MODADLER = 65521;
+
+    size_t i = 0;
+    while (s[i] != '\0')
+    {
+        a = (a + s[i]) % MODADLER;
+        b = (b + a) % MODADLER;
+        i++;
+    }
+    return (b << 16) | a;
+}
+
+/**
+ * @brief Test function for ::adler32
+ */
+void test_adler32()
+{
+    assert(adler32("Hello World") == 403375133);
+    assert(adler32("Hello World!") == 474547262);
+    assert(adler32("Hello world") == 413860925);
+    assert(adler32("Hello world!") == 487130206);
+    printf("Tests passed\n");
+}
+
+/** @} */
+
+/** Main function */
+int main()
+{
+    test_adler32();
+    return 0;
+}