Added "strrchr" optimizaion a matching unit test and tiny unit test framework. (Documentation for that will follow later)

testcode/lib/strrchr-test.c

@@ -0,0 +1,38 @@
+#include <unittest.h>
+#include <string.h>
+                                                    
+static char TestString[] = "01234567890123456789";	// two times the same string
+static char Found[256];
+
+TEST
+{
+    unsigned len;
+    unsigned i;
+    char*    p;
+
+    len = strlen(TestString)/2;	// test only one half of the string, to find last appearance
+
+    /* Search for all characters in the string, including the terminator */
+    for (i = 0; i < len; ++i)
+    {
+        /* Search for this char */
+        p = strrchr (TestString, TestString[i]);
+        ASSERT_AreEqual(i+len, p-TestString, "%u", "Unexpected location of character '%c' found!" COMMA TestString[i]);
+
+        /* Mark the char as checked */
+        Found[TestString[i]] = 1;
+    }
+
+    /* Search for all other characters and make sure they aren't found */
+    for (i = 0; i < 256; ++i)
+    {
+        if (!Found[i])
+        {
+            p = strrchr (TestString, i);
+            ASSERT_IsFalse(p, "Unexpected location of character '%c' found!" COMMA TestString[i]);
+        }
+    }
+}
+ENDTEST
+
+