Added minimalistic terminal program.

So far there was no sample code at all making use of the serial drivers.

samples/terminal.c

@@ -0,0 +1,76 @@
+/*
+** Minimalistic terminal program.
+**
+** Makes use of the serial drivers.
+**
+** 2022-12-23, Oliver Schmidt (ol.sc@web.de)
+**
+*/
+
+
+
+#include <cc65.h>
+#include <conio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <serial.h>
+
+
+static void check (const char* msg, unsigned char err)
+{
+    if (err == SER_ERR_OK) {
+        return;
+    }
+
+    printf ("%s:0x%02x\n", msg, err);
+    if (doesclrscrafterexit ()) {
+        cgetc ();
+    }
+    exit (1);
+}
+
+
+void main (void)
+{
+    const struct ser_params par = {
+        SER_BAUD_9600,
+        SER_BITS_8,
+        SER_STOP_1,
+        SER_PAR_NONE,
+        SER_HS_HW
+    };
+
+    check ("ser_install", ser_install (ser_static_stddrv));
+
+    check ("ser_open", ser_open (&par));
+
+    atexit ((void (*)) ser_close);
+
+    printf ("Serial Port: 9600-8-1-N RTS/CTS\n"
+            "Simple Term: Press ESC for exit\n");
+
+    while (1)
+    {
+        char chr;
+
+        if (kbhit ())
+        {
+            chr = cgetc ();
+
+            if (chr == CH_ESC) {
+                putchar ('\n');
+                return;
+            }
+
+            if (ser_put (chr) == SER_ERR_OK) {
+                putchar (chr);
+            } else {
+                putchar ('\a');
+            }
+        }
+
+        if (ser_get (&chr) == SER_ERR_OK) {
+            putchar (chr);
+        }
+    }
+}