初始版本

external/protothreads/pt-1.4/README

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+Protothreads are extremely lightweight stackless threads designed for
+severely memory constrained systems such as small embedded systems or
+sensor network nodes. Protothreads can be used with or without an
+underlying operating system.
+
+Protothreads provides a blocking context on top of an event-driven
+system, without the overhead of per-thread stacks. The purpose of
+protothreads is to implement sequential flow of control without
+complex state machines or full multi-threading.
+
+Main features:
+
+    * No machine specific code - the protothreads library is pure C
+    * Does not use error-prone functions such as longjmp()
+    * Very small RAM overhead - only two bytes per protothread
+    * Can be used with or without an OS
+    * Provides blocking wait without full multi-threading or
+      stack-switching
+    * Freely available under a BSD-like open source license    
+
+Example applications:
+
+    * Memory constrained systems
+    * Event-driven protocol stacks
+    * Small embedded systems
+    * Sensor network nodes
+
+The protothreads library is released under an open source BSD-style
+license that allows for both non-commercial and commercial usage. The
+only requirement is that credit is given.
+
+The protothreads library was written by Adam Dunkels <adam@sics.se>
+with support from Oliver Schmidt <ol.sc@web.de>.
+
+More information and new versions can be found at the protothreads
+homepage:
+		     http://www.sics.se/~adam/pt/
+
+Documentation can be found in the doc/ subdirectory.
+
+Two example programs illustrating the use of protothreads can be found
+in this directory:
+
+   example-small.c         A small example showing how to use protothreads
+   example-buffer.c        The bounded buffer problem with protothreads
+   example-codelock.c	   A code lock with simulated key input
+
+To compile the examples, simply run "make".
+
+
+Adam Dunkels, 3 June 2006