chdir and friends

libsrc/rp6502/f_chdrive.c

@@ -0,0 +1,16 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_chdrive (const char* name)
+{
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    return ria_call_int (RIA_OP_CHDRIVE);
+}