diff --git a/LICENSE b/LICENSE
index 9c31dda..2504d2b 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,14 +1,13 @@
-DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+Copyright 2019 Denis "ftc" Denisov
 
-Version 2, December 2004
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
 
-Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+    http://www.apache.org/licenses/LICENSE-2.0
 
-Everyone is permitted to copy and distribute verbatim or modified copies of
-this license document, and changing it is allowed as long as the name is changed.
-
-DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
-
-TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-
-   0. You just DO WHAT THE FUCK YOU WANT TO.
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
\ No newline at end of file
diff --git a/README.md b/README.md
index 5e4f41a..39b3901 100755
--- a/README.md
+++ b/README.md
@@ -69,10 +69,64 @@ Returns `true` on success, `false` otherwise.
 
 ### posix_sem_post($semaphore)
 
+Unlocks semaphore. If the semaphore's value consequently becomes greater than zero, then
+another process or thread blocked in a sem_wait call will be woken
+up and proceed to lock the semaphore.
+
+Parameters:
+* $semaphore - semaphore resource to unlock (acquired via `posix_sem_open`).
+
+Returns `true` on success, `false` otherwise.
+
+
 ### posix_sem_wait($semaphore)
 
+Locks a semaphore. If
+the semaphore's value is greater than zero, then the decrement
+proceeds, and the function returns, immediately.  If the semaphore
+currently has the value zero, then the call blocks until either it
+becomes possible to perform the decrement (i.e., the semaphore value
+rises above zero), or a signal handler interrupts the call.
+
+Parameters:
+* $semaphore - semaphore resource to unlock (acquired via `posix_sem_open`).
+
+Returns `true` on success, `false` otherwise.
+
+### posix_sem_trywait($semaphore)
+
+The same as `posix_sem_wait`, except that if the decrement
+cannot be immediately performed, then call returns an error (last error
+set to EAGAIN) instead of blocking.
+
+### posix_sem_timedwait($semaphore, $timeout_sec, $timeout_nsec = 0)
+
+Tries to lock a semaphore (as `posix_sem_wait`), but if lock could not 
+be performed in a specified timeout, returns and sets last error to ETIMEDOUT.
+
+Parameters:
+* $semaphore - semaphore resource to unlock (acquired via `posix_sem_open`).
+* $timeout_sec - part of the timeout in seconds.
+* $timeout_nsec - part of the timeout in nanoseconds.
+
+Total timeout is computed as `$timeout_sec * 1000000000 + $timeout_nsec` and is
+measured in nanoseconds.
+
 ### posix_sem_getvalue($semaphore)
 
+Gets value of specified semaphore.
+
+Parameters:
+* $semaphore - semaphore resource which value to get (acquired via `posix_sem_open`).
+
+Returns semaphore value on success and `null` on error.
+
+Please note that underlying function `sem_getvalue` can behave differently according to
+POSIX specification, so please read your OS documentation on that.
+
+### posix_sem_error()
+
+Returns value of last error occured during call of another semaphore-related function.
 
 ## Notes for PHP users