Allow execution of sub-SSMs

A subssm will be executed, and upon completion the parent state machine
will either be advanced to the next state or aborted with error, depending
on the outcome of the subssm.

Also add some debug messages.

1 files changed, 23 insertions, 0 deletions

diff --git a/libfprint/drv.c b/libfprint/drv.c
index 3055e99..9ee54cf 100644
--- a/libfprint/drv.c
+++ b/libfprint/drv.c
@@ -360,6 +360,7 @@ void fpi_ssm_free(struct fpi_ssm *machine)
 /* Invoke the state handler */
 static void __ssm_call_handler(struct fpi_ssm *machine)
 {
+	fp_dbg("%p entering state %d", machine, machine->cur_state);
 	machine->handler(machine);
 }
 
@@ -374,11 +375,33 @@ void fpi_ssm_start(struct fpi_ssm *ssm, ssm_completed_fn callback)
 	__ssm_call_handler(ssm);
 }
 
+static void __subsm_complete(struct fpi_ssm *ssm)
+{
+	struct fpi_ssm *parent = ssm->parentsm;
+	BUG_ON(!parent);
+	if (ssm->error)
+		fpi_ssm_mark_aborted(parent, ssm->error);
+	else
+		fpi_ssm_next_state(parent);
+	fpi_ssm_free(ssm);
+}
+
+/* start a SSM as a child of another. if the child completes successfully, the
+ * parent will be advanced to the next state. if the child aborts, the parent
+ * will be aborted with the same error code. the child will be automatically
+ * freed upon completion/abortion. */
+void fpi_ssm_start_subsm(struct fpi_ssm *parent, struct fpi_ssm *child)
+{
+	child->parentsm = parent;
+	fpi_ssm_start(child, __subsm_complete);
+}
+
 /* Mark a ssm as completed successfully. */
 void fpi_ssm_mark_completed(struct fpi_ssm *machine)
 {
 	BUG_ON(machine->completed);
 	machine->completed = TRUE;
+	fp_dbg("%p completed with status %d", machine, machine->error);
 	if (machine->callback)
 		machine->callback(machine);
 }