[RFC V2 03/21] rv/include: Add helper functions for deterministic automata

[Daniel Bristot de Oliveira <bristot@kernel.org>]

Formally, a deterministic automaton, denoted by G, is defined as a
quintuple:

  G = { X, E, f, x_0, X_m }

where:
	- X is the set of states;
	- E is the finite set of events;
	- x_0 is the initial state;
	- X_m (subset of X) is the set of marked states.
	- f : X x E -> X $ is the transition function. It defines the
	  state transition in the occurrence of a event from E in
	  the state X. In the special case of deterministic automata,
	  the occurence of the event in E in a state in X has a
	  deterministic next state from X.

An automaton can also be represented using a graphical format of
vertices (nodes) and edges. The open-source tool Graphviz can produce
this graphic format using the (textual) DOT language as the source code.

The dot2c tool presented in this paper:

DE OLIVEIRA, Daniel Bristot; CUCINOTTA, Tommaso; DE OLIVEIRA, Romulo
Silva. Efficient formal verification for the Linux kernel. In:
International Conference on Software Engineering and Formal Methods.
Springer, Cham, 2019. p. 315-332.

Translates a deterministic automaton in the DOT format into a C
source code representation that to be used for monitoring.

This header file implements helper functions to facilitate the usage
of the C output from dot2c for monitoring.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
---
 include/rv/automata.h | 52 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 include/rv/automata.h

diff --git a/include/rv/automata.h b/include/rv/automata.h
new file mode 100644
index 000000000000..dfd0bbf0dc5c
--- /dev/null
+++ b/include/rv/automata.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Deterministic automata helper functions, to be used with the automata
+ * models in C generated by the dot2k tool.
+ *
+ * The dot2k tool is available at https://gitlab.com/linux-rv-tools/dot2/.
+ *
+ * Copyright (C) 2019-2022 Daniel Bristot de Oliveira <bristot@kernel.org>
+ */
+
+#define DECLARE_AUTOMATA_HELPERS(name, type)					\
+										\
+static inline void *model_get_model_##name(void)				\
+{										\
+	return (void *) &automaton_##name;					\
+}										\
+										\
+char *model_get_state_name_##name(enum states_##name state)			\
+{										\
+	return automaton_##name.state_names[state];				\
+}										\
+										\
+char *model_get_event_name_##name(enum events_##name event)			\
+{										\
+	return automaton_##name.event_names[event];				\
+}										\
+										\
+static inline type model_get_init_state_##name(void)				\
+{										\
+	return automaton_##name.initial_state;					\
+}										\
+										\
+static inline type 								\
+model_get_next_state_##name(enum states_##name curr_state,			\
+			    enum events_##name event)				\
+{										\
+	if ((curr_state < 0) || (curr_state > state_max))			\
+		return -1;							\
+										\
+	if ((event < 0) || (event > event_max))					\
+		return -1;							\
+										\
+	return automaton_##name.function[curr_state][event];			\
+}										\
+										\
+static inline bool model_is_final_state_##name(enum states_##name state)	\
+{										\
+	if ((state < 0) || (state > state_max))					\
+		return 0;							\
+										\
+	return !!automaton_##name.final_states[state];				\
+}
-- 
2.33.1