first re-commit.

pigpio-master/EXAMPLES/C/ROTARY_ENCODER/test_rotary_encoder.c

@@ -0,0 +1,47 @@
+#include <stdio.h>
+
+#include <pigpio.h>
+
+#include "rotary_encoder.h"
+
+/*
+
+REQUIRES
+
+A rotary encoder contacts A and B connected to separate gpios and
+the common contact connected to Pi ground.
+
+TO BUILD
+
+gcc -o rot_enc_c test_rotary_encoder.c rotary_encoder.c -lpigpio -lrt
+
+TO RUN
+
+sudo ./rot_enc_c
+
+*/
+
+void callback(int way)
+{
+   static int pos = 0;
+
+   pos += way;
+
+   printf("pos=%d\n", pos);
+}
+
+int main(int argc, char *argv[])
+{
+   Pi_Renc_t * renc;
+
+   if (gpioInitialise() < 0) return 1;
+
+   renc = Pi_Renc(7, 8, callback);
+
+   sleep(300);
+
+   Pi_Renc_cancel(renc);
+
+   gpioTerminate();
+}
+