sam: Select the IO Backend at runtime when a device name is specified

The configure part is more messy than I had hoped for. One can not
just specify @VARIABLE_THAT_HAS_SOURCES@, I need to go through the
every backend and add the sourcecode.

Makefile.am

@@ -4,7 +4,21 @@ AUTOMAKE_OPTIONS = gnu
 
 bin_PROGRAMS = sam7
 
-sam7_SOURCES = main.c io.c io_@IOTYPE@.c samba.c cmd.c
+sam7_SOURCES = main.c io.c samba.c cmd.c
+
+if HAVE_IOKIT
+sam7_SOURCES += io_iokit.c
+endif
+if HAVE_WIN32
+sam7_SOURCES += io_win32.c
+endif
+if HAVE_POSIX
+sam7_SOURCES += io_posix.c
+endif
+if HAVE_LIBUSB
+sam7_SOURCES += io_libusb.c
+endif
+
 noinst_HEADERS = io.h samba.h cmd.h loader128_data.h loader256_data.h 
 
 EXTRA_DIST = driver/Makefile driver/at91.c \

configure.in

@@ -15,14 +15,15 @@ AC_PROG_MAKE_SET
 case "${host}" in
      *-*-darwin* )
        LIBS="$LIBS -framework IOKIT -framework CoreFoundation"
-       IOTYPE="iokit"
+       have_iokit="true"
      ;;	    
      *-*-cygwin* )
        LIBS="$LIBS -lsetupapi"
-       IOTYPE="win32"
+       have_win32="true"
      ;;	    
      * )
-       AC_CHECK_LIB(usb,usb_init,IOTYPE="libusb";LIBS="$LIBS -lusb",IOTYPE="posix")
+       have_posix="true"
+       AC_CHECK_LIB(usb,usb_init,have_libusb="true";LIBS="$LIBS -lusb")
        
      ;;
 esac
@@ -37,8 +38,9 @@ AC_CHECK_HEADERS(ctype.h,,)
 AC_CHECK_HEADERS(endian.h,,)
 
 
-
-
-AC_SUBST(IOTYPE)
+AM_CONDITIONAL([HAVE_IOKIT], [test x$have_iokit = xtrue])
+AM_CONDITIONAL([HAVE_WIN32], [test x$have_win32 = xtrue])
+AM_CONDITIONAL([HAVE_POSIX], [test x$have_posix = xtrue])
+AM_CONDITIONAL([HAVE_LIBUSB],[test x$have_libusb = xtrue])
 
 AC_OUTPUT(Makefile)

io.c

@@ -31,14 +31,7 @@ int io_driver_register(struct io_driver *driver)
 	return 0;
 }
 
-struct io_driver *io_driver_at(int i)
-{
-	if (i >= last_driver)
-		return NULL;
-	return drivers[i];
-}
-
-void io_driver_activate(struct io_driver *driver)
+static void io_driver_activate(struct io_driver *driver)
 {
 	printf("Activating driver: %s\n", driver->name);
 	g_driver = driver;
@@ -63,3 +56,24 @@ int io_read(void *buff, int len)
 {
 	return g_driver->io_read(buff, len);
 }
+
+void io_driver_select_backend(const char *name)
+{
+  int i;
+  struct io_driver *driver = drivers[0];
+
+  for ( i = 0; ;++i) {
+    if (!drivers[i])
+      break;
+
+    if (name && strcmp("posix", drivers[i]->name) == 0) {
+      driver = drivers[i];
+      break;
+    } else if (!name && strcmp("libusb", drivers[i]->name) == 0) {
+      driver = drivers[i];
+      break;
+    }
+  }
+
+  io_driver_activate(driver);
+}

io.h

@@ -28,8 +28,7 @@ struct io_driver {
 };
 
 int io_driver_register(struct io_driver *driver);
-struct io_driver *io_driver_at(int);
-void io_driver_activate(struct io_driver *driver);
+void io_driver_select_backend(const char *line);
 
 int io_init( char *dev );
 int io_cleanup( void );

main.c

@@ -88,8 +88,8 @@ int main( int argc, char *argv[] )
     }
   }
 
-  /* Activate a default driver */
-  io_driver_activate(io_driver_at(0));
+  /* If we have a path, attempt to use the posix backend */
+  io_driver_select_backend(line);
 
   if( io_init( line ) < 0 ) {
     fprintf(stderr, "Failed to initialize the SAM7 device.\n");