README.scrypt: Document psw kernel

README.scrypt

@@ -103,10 +103,11 @@ kernel, threads, thread-concurrency, lookup-gap
 
 kernel:
 This selects the OpenCL code to use. By default, the kernel named "scrypt" will
-be used. BFGMiner also includes Zuikkis's optimised version, which you can use
-with:
+be used. BFGMiner also includes optimised versions from Zuikkis and Pavel
+Semjanov, which you can specify by filename:
     --set-device OCL:kernel=zuikkis
-Note that this version requires lookup-gap set to 2 (which is default).
+    --set-device OCL:kernel=psw
+Note that Zuikkis' version requires the default lookup-gap of 2.
 
 thread-concurrency:
 This tunes the optimal size of work that scrypt can do. It is internally tuned

opencl/psw.cl

@@ -29,6 +29,8 @@
  * online backup system.
  */
 
+// kernel-interface: scrypt
+
 __constant uint ES[2] = { 0x00FF00FF, 0xFF00FF00 };
 __constant uint K[] = {
 	0x428a2f98U,