sdvxio-kfca: add some docs and address some comments

Module.mk

@@ -472,6 +472,7 @@ $(zipdir)/bst.zip: \
 
 $(zipdir)/doc.zip: \
 		doc/iidxhook \
+		doc/sdvxhook \
 		doc/jbhook \
 		doc/tools \
 		| $(zipdir)/

doc/sdvxhook/sdvxio-kfca.md

@@ -0,0 +1,14 @@
+This library talks to a KFCA node through ACIO and implements the sdvxio API of BT5.
+Thus, it allows you to use a KFCA device board with *any* version of SDVX that is supported by BT5.
+
+# Setup
+* Rename sdvxio-kfca.dll to sdvxio.dll.
+* Ensure that your gamestart.bat actually injects the appropriate sdvxhook dll,
+for example:
+```
+launcher -K iidxhook2.dll soundvoltex.dll ...*
+```
+* sdvxio-kfca expects a KFCA device on COM3 by default
+* You can change the port by settings the SDVXIO_KFCA_PORT envvar
+* If there is also an ICCA device on the same ACIO bus, it cannot be used with eamio-icca at this time
+* Please connect any additional acio devices to their own port (ex: SDVX5 expects an ICCA by itself on COM2)

src/main/sdvxio-kfca/sdvxio.c

@@ -72,25 +72,31 @@ bool sdvx_io_init(
         aciodrv_device_get_node_product_ident(i, product);
         log_info(
             "> %d: %c%c%c%c\n",
-            i + 1,
+            i,
             product[0],
             product[1],
             product[2],
             product[3]);
 
         if (!memcmp(product, "KFCA", 4)) {
+            if (kfca_node_id != -1) {
+                log_warning("Multiple KFCA found! Using highest node id.");
+            }
             kfca_node_id = i;
         }
     }
 
     if (kfca_node_id != -1) {
+        log_warning("Using KFCA on node: %d", kfca_node_id);
         aciodrv_kfca_init(kfca_node_id);
+
         running = true;
+        log_warning("sdvxio-kfca now running");
     } else {
         log_warning("No KFCA device found");
     }
 
-    return true;
+    return running;
 }
 
 void sdvx_io_fini(void)