Add Finite State Machine abstraction code

This code is supposed to formalize some of the state machine handling in
Osmocom code.

Change-Id: I0b0965a912598c1f6b84042a99fea9d522642466
Reviewed-on: https://gerrit.osmocom.org/163
Tested-by: Jenkins Builder
Reviewed-by: Harald Welte <laforge@gnumonks.org>

3 files changed, 166 insertions, 0 deletions

diff --git a/tests/fsm/fsm_test.c b/tests/fsm/fsm_test.c
new file mode 100644
index 00000000..84c2ae4d
--- /dev/null
+++ b/tests/fsm/fsm_test.c
@@ -0,0 +1,155 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/fsm.h>
+
+enum {
+	DMAIN,
+};
+
+static void *g_ctx;
+
+
+enum test_fsm_states {
+	ST_NULL = 0,
+	ST_ONE,
+	ST_TWO,
+};
+
+enum test_fsm_evt {
+	EV_A,
+	EV_B,
+};
+
+static void test_fsm_null(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case EV_A:
+		OSMO_ASSERT(data == (void *) 23);
+		osmo_fsm_inst_state_chg(fi, ST_ONE, 0, 0);
+		break;
+	default:
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+static void test_fsm_one(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case EV_B:
+		OSMO_ASSERT(data == (void *) 42);
+		osmo_fsm_inst_state_chg(fi,ST_TWO, 1, 2342);
+		break;
+	default:
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+static void test_fsm_tmr_cb(struct osmo_fsm_inst *fi)
+{
+	OSMO_ASSERT(fi->T == 2342);
+	OSMO_ASSERT(fi->state == ST_TWO);
+	LOGP(DMAIN, LOGL_INFO, "Timer\n");
+
+	exit(0);
+}
+
+static struct osmo_fsm_state test_fsm_states[] = {
+	[ST_NULL] = {
+		.in_event_mask = (1 << EV_A),
+		.out_state_mask = (1 << ST_ONE),
+		.name = "NULL",
+		.action = test_fsm_null,
+	},
+	[ST_ONE]= {
+		.in_event_mask = (1 << EV_B),
+		.out_state_mask = (1 << ST_TWO),
+		.name = "ONE",
+		.action= test_fsm_one,
+	},
+	[ST_TWO]= {
+		.in_event_mask = 0,
+		.name = "TWO",
+		.action = NULL,
+	},
+};
+
+static struct osmo_fsm fsm = {
+	.name = "Test FSM",
+	.states = test_fsm_states,
+	.num_states = ARRAY_SIZE(test_fsm_states),
+	.log_subsys = DMAIN,
+};
+
+static int foo(void)
+{
+	struct osmo_fsm_inst *fi;
+
+	LOGP(DMAIN, LOGL_INFO, "Checking FSM allocation\n");
+	fi = osmo_fsm_inst_alloc(&fsm, g_ctx, NULL, LOGL_DEBUG, NULL);
+	OSMO_ASSERT(fi);
+	OSMO_ASSERT(fi->fsm == &fsm);
+	OSMO_ASSERT(!strncmp(osmo_fsm_inst_name(fi), fsm.name, strlen(fsm.name)));
+	OSMO_ASSERT(fi->state == ST_NULL);
+	OSMO_ASSERT(fi->log_level == LOGL_DEBUG);
+
+	/* Try invalid state transition */
+	osmo_fsm_inst_dispatch(fi, EV_B, (void *) 42);
+	OSMO_ASSERT(fi->state == ST_NULL);
+
+	/* Legitimate state transition */
+	osmo_fsm_inst_dispatch(fi, EV_A, (void *) 23);
+	OSMO_ASSERT(fi->state == ST_ONE);
+
+	/* Legitimate transition with timer */
+	fsm.timer_cb = test_fsm_tmr_cb;
+	osmo_fsm_inst_dispatch(fi, EV_B, (void *) 42);
+	OSMO_ASSERT(fi->state == ST_TWO);
+
+
+	return 0;
+}
+
+static const struct log_info_cat default_categories[] = {
+	[DMAIN] = {
+		.name = "DMAIN",
+		.description = "Main",
+		.enabled = 1, .loglevel = LOGL_DEBUG,
+	},
+};
+
+static const struct log_info log_info = {
+	.cat = default_categories,
+	.num_cat = ARRAY_SIZE(default_categories),
+};
+
+int main(int argc, char **argv)
+{
+	struct log_target *stderr_target;
+
+	osmo_fsm_log_addr(false);
+
+	log_init(&log_info, NULL);
+	stderr_target = log_target_create_stderr();
+	log_add_target(stderr_target);
+	log_set_print_filename(stderr_target, 0);
+
+	g_ctx = NULL;
+	osmo_fsm_register(&fsm);
+
+	foo();
+
+	while (1) {
+		osmo_select_main(0);
+	}
+
+	exit(0);
+}
diff --git a/tests/fsm/fsm_test.err b/tests/fsm/fsm_test.err
new file mode 100644
index 00000000..b9c738c6
--- /dev/null
+++ b/tests/fsm/fsm_test.err
@@ -0,0 +1,11 @@
+Checking FSM allocation
+Test FSM{NULL}: Allocated
+Test FSM{NULL}: Received Event 1
+Test FSM(NULL): Event 1 not permitted
+Test FSM{NULL}: Received Event 0
+Test FSM{NULL}: state_chg to ONE
+Test FSM{ONE}: Received Event 1
+Test FSM{ONE}: state_chg to TWO
+Test FSM{TWO}: Timeout of T2342
+Timer
+
\ No newline at end of file
diff --git a/tests/fsm/fsm_test.ok b/tests/fsm/fsm_test.ok
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/tests/fsm/fsm_test.ok