Tools:HAL_Linux_Essentials:add rcinput test code

the test code performs continuous reads from ring buffer shared with PRU0

Tools/Linux_HAL_Essentials/test_codes/rcin_test.c

@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <sys/time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <stdint.h>
+    
+#define PRUSS_SHAREDRAM_BASE     0x4a312000
+#define NUM_RING_ENTRIES 200
+
+struct ring_buffer {
+    volatile uint16_t ring_head;
+    volatile uint16_t ring_tail;
+    struct __attribute__((__packed__)) {
+           uint16_t pin_value;
+           uint16_t delta_t;
+    } buffer[NUM_RING_ENTRIES];
+};
+
+static volatile struct ring_buffer *ring_buffer;
+static FILE *logf;
+
+
+void startup(void)
+{
+    logf = fopen("/tmp/pintiming.dat", "w");
+}
+
+void check_for_rcin(void)
+{
+    while (ring_buffer->ring_head != ring_buffer->ring_tail) {
+        fprintf(logf,"%u %u\n",
+                (unsigned int)ring_buffer->buffer[ring_buffer->ring_head].pin_value,
+                (unsigned int)ring_buffer->buffer[ring_buffer->ring_head].delta_t);
+            ring_buffer->ring_head = (ring_buffer->ring_head + 1) % NUM_RING_ENTRIES;
+    }
+}
+
+void main(){
+	
+	int mem_fd = open("/dev/mem", O_RDWR|O_SYNC);
+    ring_buffer = (volatile struct ring_buffer*) mmap(0, 0x1000, PROT_READ|PROT_WRITE, MAP_SHARED, mem_fd, PRUSS_SHAREDRAM_BASE);
+    close(mem_fd);
+    ring_buffer->ring_head = 0;
+    startup();
+    while(1){
+        check_for_rcin();
+    }
+}