diff --git a/README.md b/README.md
new file mode 100644
index 0000000..b56b413
--- /dev/null
+++ b/README.md
@@ -0,0 +1,118 @@
+# PHP atomic counter extension
+
+Simple SysV semaphore counter. It will be automatically undone 
+when the process terminates.
+
+## Supported platform
+* Linux (kernel > 2.1) (not Solaris)
+
+## Install
+
+```
+phpize
+./configure
+make
+make install
+```
+
+Add `extension=counterlock.so` to your php.ini configuration
+
+### Install on CentOS and RHEL
+```
+/opt/remi/php71/root/usr/bin/phpize
+./configure --with-php-config=/opt/remi/php71/root/usr/bin/php-config
+make
+make install
+echo "extension=counterlock.so" > /etc/opt/remi/php71/php.d/20-counerlock.ini
+```
+
+## Run test
+
+```
+phpize
+./configure
+make
+make test
+```
+
+## Example Usage
+
+```php
+<?php
+
+$res = counter_create(1863);
+echo counter_value($res) . PHP_EOL;
+counter_increment($res);
+echo counter_value($res) . PHP_EOL;; 
+counter_decrement($res);
+
+/* Result
+0
+1
+```
+
+## Provided function.
+
+```php
+<?php
+
+// Start of counterlock.
+
+/**
+ * Get or create a semaphore counter id
+ * 
+ * @param int $key
+ * @param int $perm [optional] <p>
+ * The semaphore permissions. Actually this value is
+ * set only if the process finds it is the only process currently
+ * attached to the semaphore.
+ * </p>
+ *
+ * @return resource a positive counter identifier on success, or <b>FALSE</b> on
+ * error.
+ */
+function counter_create ($key, $perm = 0666) {}
+
+/**
+ * Increment a counter
+ * @param resource $resource <p>
+ * <i>resource</i> is a resource, obtained from <b>counter_create</b>.
+ * </p>
+ * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
+ */
+function counter_increment ($resource) {}
+
+/**
+ * Increment a counter
+ * @param resource $resource <p>
+ * A resource handle as returned by
+ * <b>counter_create</b>.
+ * </p>
+ * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
+ */
+function counter_decrement ($resource) {}
+
+/**
+ * Get counter value.
+ * 
+ * @param resource $resource <p>
+ * A resource handle as returned by
+ * <b>counter_create</b>.
+ * </p>
+ * @return integer|false <b>FALSE</b> on failure.
+ */
+function counter_value ($resource) {}
+
+/**
+ * Remove a System V semaphore for counter
+ * @param resource $resource <p>
+ * A semaphore resource identifier as returned
+ * by <b>sem_get</b>.
+ * </p>
+ * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
+ */
+function counter_remove ($resource) {}
+
+// End of counterlock.
+
+```
diff --git a/counterlock.php b/counterlock.php
index d7e2cae..83d45c5 100644
--- a/counterlock.php
+++ b/counterlock.php
@@ -1,21 +1,61 @@
 <?php
-$br = (php_sapi_name() == "cli")? "":"<br>";
-
-if(!extension_loaded('counterlock')) {
-	dl('counterlock.' . PHP_SHLIB_SUFFIX);
-}
-$module = 'counterlock';
-$functions = get_extension_funcs($module);
-echo "Functions available in the test extension:$br\n";
-foreach($functions as $func) {
-    echo $func."$br\n";
-}
-echo "$br\n";
-$function = 'confirm_' . $module . '_compiled';
-if (extension_loaded($module)) {
-	$str = $function($module);
-} else {
-	$str = "Module $module is not compiled into PHP";
-}
-echo "$str\n";
-?>
+
+// Start of counterlock.
+
+/**
+ * Get or create a semaphore counter id
+ *
+ * @param int $key
+ * @param int $perm [optional] <p>
+ * The semaphore permissions. Actually this value is
+ * set only if the process finds it is the only process currently
+ * attached to the semaphore.
+ * </p>
+ *
+ * @return resource a positive counter identifier on success, or <b>FALSE</b> on
+ * error.
+ */
+function counter_create ($key, $perm = 0666) {}
+
+/**
+ * Increment a counter
+ * @param resource $resource <p>
+ * <i>resource</i> is a resource, obtained from <b>counter_create</b>.
+ * </p>
+ * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
+ */
+function counter_increment ($resource) {}
+
+/**
+ * Increment a counter
+ * @param resource $resource <p>
+ * A resource handle as returned by
+ * <b>counter_create</b>.
+ * </p>
+ * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
+ */
+function counter_decrement ($resource) {}
+
+/**
+ * Get counter value.
+ *
+ * @param resource $resource <p>
+ * A resource handle as returned by
+ * <b>counter_create</b>.
+ * </p>
+ * @return integer|false <b>FALSE</b> on failure.
+ */
+function counter_value ($resource) {}
+
+/**
+ * Remove a System V semaphore for counter
+ * @param resource $resource <p>
+ * A semaphore resource identifier as returned
+ * by <b>sem_get</b>.
+ * </p>
+ * @return bool <b>TRUE</b> on success or <b>FALSE</b> on failure.
+ */
+function counter_remove ($resource) {}
+
+// End of counterlock.
+
diff --git a/example.php b/example.php
deleted file mode 100644
index 8b6ff39..0000000
--- a/example.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-$res = counter_create(1863);
-echo counter_value($res) . PHP_EOL;
-counter_increment($res);
-echo counter_value($res) . PHP_EOL;; 
-counter_decrement($res);