first re-commit.

pigpio-master/EXAMPLES/CPP/IR_RECEIVER/README

@@ -0,0 +1,4 @@
+Class to hash a code from an IR receiver (reading an IR remote control).
+
+Follow the instructions in the test file to build and run.
+

pigpio-master/EXAMPLES/CPP/IR_RECEIVER/ir_hasher.cpp

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+#include <pigpio.h>
+
+#include "ir_hasher.hpp"
+
+void Hasher::_hash(int old_val, int new_val)
+{
+   int val;
+
+   if      (new_val < (old_val * 0.60)) val = 13;
+   else if (old_val < (new_val * 0.60)) val = 23;
+   else                                 val = 2;
+
+   hash_val ^= val;
+   hash_val *= 16777619; /* FNV_PRIME_32 */
+}
+
+void Hasher::_callback(int gpio, int level, uint32_t tick)
+{
+   if (level != PI_TIMEOUT)
+   {
+      if (in_code == 0)
+      {
+         in_code = 1;
+
+         gpioSetWatchdog(mygpio, mytimeout);
+
+         hash_val = 2166136261U; /* FNV_BASIS_32 */
+
+         edges = 1;
+
+         t1 = 0;
+         t2 = 0;
+         t3 = 0;
+         t4 = tick;
+      }
+      else
+      {
+         edges++;
+
+         t1 = t2;
+         t2 = t3;
+         t3 = t4;
+         t4 = tick;
+
+         if (edges > 3) _hash(t2-t1, t4-t3);
+      }
+   }
+   else
+   {
+      if (in_code)
+      {
+         in_code = 0;
+
+         gpioSetWatchdog(mygpio, 0);
+
+         if (edges > 12) /* Anything less is probably noise. */
+         {
+            (mycallback)(hash_val);
+         }
+      }
+   }
+}
+
+void Hasher::_callbackExt(int gpio, int level, uint32_t tick, void *user)
+{
+   /*
+      Need a static callback to link with C.
+   */
+
+   Hasher *mySelf = (Hasher *) user;
+
+   mySelf->_callback(gpio, level, tick); /* Call the instance callback. */
+}
+
+Hasher::Hasher(int gpio, HasherCB_t callback, int timeout)
+{
+   /*
+      Initialises an IR remote hasher on a gpio.  A gap of timeout
+      milliseconds indicates the end of the remote key press.
+   */
+   mygpio     = gpio;
+   mycallback = callback;
+   mytimeout  = timeout;
+
+   in_code = 0;
+
+   gpioSetMode(gpio, PI_INPUT);
+
+   gpioSetAlertFuncEx(gpio, _callbackExt, (void *)this);
+}
+

pigpio-master/EXAMPLES/CPP/IR_RECEIVER/ir_hasher.hpp

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+#ifndef IR_RX_HASHER_HPP
+#define IR_RX_HASHER_HPP
+
+#include <stdint.h>
+
+typedef void (*HasherCB_t)(uint32_t);
+
+class Hasher
+{
+
+   /*
+   This class forms a hash over the IR pulses generated by an
+   IR remote.
+
+   The remote key press is not converted into a code in the manner of
+   the lirc module.  No attempt is made to decode the type of protocol
+   used by the remote.  The hash is likely to be unique for different
+   keys and different remotes but this is not guaranteed.
+
+   This hashing process works for some remotes/protocols but not for
+   others.  The only way to find out if it works for one or more of
+   your remotes is to try it and see.
+   */
+
+   int mygpio, mytimeout;
+   HasherCB_t mycallback;
+   int in_code;
+   uint32_t hash_val;
+   int edges;
+   uint32_t t1, t2, t3, t4;
+
+   void _hash(int old_val, int new_val);
+   void _callback(int gpio, int level, uint32_t tick);
+
+   /* Need a static callback to link with C. */
+   static void _callbackExt(int gpio, int level, uint32_t tick, void *user);
+
+   public:
+
+   Hasher(int gpio, HasherCB_t callback, int timeout=5);
+};
+
+#endif
+

pigpio-master/EXAMPLES/CPP/IR_RECEIVER/test_ir_hasher.cpp

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+#include <iostream>
+
+#include <pigpio.h>
+
+#include "ir_hasher.hpp"
+
+/*
+
+REQUIRES
+
+An IR receiver output pin connected to a Pi gpio.
+
+TO BUILD
+
+g++ -o ir_hash_cpp test_ir_hasher.cpp ir_hasher.cpp -lpigpio -lrt -lpthread
+
+TO RUN
+
+sudo ./ir_hash_cpp
+
+*/
+
+void callback(uint32_t hash)
+{
+   std::cout << "hash=" << hash << std::endl;
+}
+
+int main(int argc, char *argv[])
+{
+   if (gpioInitialise() >= 0)
+   {
+      /* Can't instantiate a Hasher before pigpio is initialised. */
+
+      /* 
+         This assumes the output pin of an IR receiver is
+         connected to gpio 7.
+      */
+
+      Hasher ir(7, callback);
+
+      sleep(300);
+   }
+}
+