add code in README

README.md

@@ -133,6 +133,67 @@ replaying tests, it is highly recommended to add the `--no_fork`
 option on mac OS, unless you need the added crash handling (that is,
 things aren't working without that option).
 
+## Example Code
+
+```
+#include <deepstate/DeepState.hpp>
+
+using namespace deepstate;
+
+/* Simple, buggy, run-length encoding that creates "human readable"
+ * encodings by adding 'A'-1 to the count, and splitting at 26 */
+
+char* encode(const char* input) {
+  unsigned int len = strlen(input);
+  char* encoded = (char*)malloc((len*2)+1);
+  int pos = 0;
+  if (len > 0) {
+    unsigned char last = input[0];
+    int count = 1;
+    for (int i = 1; i < len; i++) {
+      if (((unsigned char)input[i] == last) && (count < 26))
+	count++;
+      else {
+	encoded[pos++] = last;
+	encoded[pos++] = 64 + count;
+	last = (unsigned char)input[i];
+	count = 1;
+      }
+    }
+    encoded[pos++] = last;
+    encoded[pos++] = 65; // Should be 64 + count
+  }
+  encoded[pos] = '\0';
+  return encoded;
+}
+
+char* decode(const char* output) {
+  unsigned int len = strlen(output);
+  char* decoded = (char*)malloc((len/2)*26);
+  int pos = 0;
+  for (int i = 0; i < len; i += 2) {
+    for (int j = 0; j < (output[i+1] - 64); j++) {
+      decoded[pos++] = output[i];
+    }
+  }
+  decoded[pos] = '\0';
+  return decoded;
+}
+
+// Can be (much) higher (e.g., > 1024) if we're using fuzzing, not symbolic execution
+#define MAX_STR_LEN 6
+
+TEST(Runlength, EncodeDecode) {
+  char* original = DeepState_CStrUpToLen(MAX_STR_LEN, "abcdef0123456789");
+  char* encoded = encode(original);
+  ASSERT_LE(strlen(encoded), strlen(original)*2) << "Encoding is > length*2!";
+  char* roundtrip = decode(encoded);
+  ASSERT_EQ(strncmp(roundtrip, original, MAX_STR_LEN), 0) <<
+    "ORIGINAL: '" << original << "', ENCODED: '" << encoded <<
+    "', ROUNDTRIP: '" << roundtrip << "'";
+}
+```
+
 ## Built-In Fuzzer
 
 Every DeepState executable provides a simple built-in fuzzer that