Add xxd commmand to gdb

.gdbinit

@@ -39,3 +39,22 @@ set mem inaccessible-by-default off
 # define target remote
 # bmconnect /dev/ttyBmpGdb
 # end
+
+
+define xxd
+  if $argc < 2
+    set $size = sizeof(*$arg0)
+  else
+    set $size = $arg1
+  end
+  dump binary memory dump.bin $arg0 ((void *)$arg0)+$size
+  eval "shell xxd -o %d dump.bin; rm dump.bin", ((void *)$arg0)
+end
+document xxd
+  Dump memory with xxd command (keep the address as offset)
+
+  xxd addr [size]
+    addr -- expression resolvable as an address
+    size -- size (in byte) of memory to dump
+            sizeof(*addr) is used by default
+end