Adds invert option, updates usage.

2 files changed, 10 insertions, 1 deletions

diff --git a/src/device/axis/axis_filter.c b/src/device/axis/axis_filter.c
index 6258ad9..d7840ca 100644
--- a/src/device/axis/axis_filter.c
+++ b/src/device/axis/axis_filter.c
@@ -122,6 +122,11 @@ int relabsd_axis_filter_new_value
       return 0;
    }
 
+   if (axis->flags[RELABSD_INVERT])
+   {
+      *value = -(*value);
+   }
+
    if (axis->flags[RELABSD_NOT_ABS])
    {
       return 1;
diff --git a/src/device/axis/axis_option.c b/src/device/axis/axis_option.c
index 7796eb7..e8d06f5 100644
--- a/src/device/axis/axis_option.c
+++ b/src/device/axis/axis_option.c
@@ -57,10 +57,14 @@ int relabsd_axis_enable_option_from_name
          );
       }
    }
-   else if (RELABSD_IS_PREFIX("notabs", option_name))
+   else if (RELABSD_IS_PREFIX("not_abs", option_name))
    {
       axis->flags[RELABSD_NOT_ABS] = 1;
    }
+   else if (RELABSD_IS_PREFIX("invert", option_name))
+   {
+      axis->flags[RELABSD_INVERT] = 1;
+   }
    else if (RELABSD_IS_PREFIX("convert_to=", option_name))
    {
       axis->convert_to =