failed approach

gomspace/libutil/include/gs/util/function_scheduler.h

@@ -0,0 +1,79 @@
+#ifndef GS_UTIL_FUNCTION_SCHEDULER
+#define GS_UTIL_FUNCTION_SCHEDULER
+/* Copyright (c) 2013-2017 GomSpace A/S. All rights reserved. */
+/**
+   @file
+
+   Function scheduler.
+
+   Simple framework for invoking functions at intervals.
+
+   Instead of creating a lot of tasks (which uses memory), this framework can be used to schedule execution of functions at specified intervals.
+
+   Once setup, calling gs_function_scheduler_execute_ms() will execute all functions timed out and return the time, until the next function has
+   to be executed or max timeout specified (or max wait time supported on the platform).
+
+   The API supports multiple schedulers, but is not thread-safe.
+
+   @note Do NOT use for time critical control, as the actual time interval is influenced by the host thread and other scheduled functions.
+*/
+
+#include <gs/util/error.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+   Scheduler handle.
+*/
+typedef struct gs_function_scheduler gs_function_scheduler_t;
+
+/**
+   Function callback.
+
+   @return timeout in mS until next callback.
+*/
+typedef uint32_t (*gs_function_scheduler_function_t)(void * user_data);
+
+/**
+   Initialize scheduler.
+   Memory is allocated once for \a max_entries.
+   @param[in] max_timeout_ms max timeout in mS.
+   @param[in] max_entries max number of entries for this scheduler.
+   @param[out] scheduler reference to created scheduler.
+   @return_gs_error_t
+*/
+gs_error_t gs_function_scheduler_create(uint32_t max_timeout_ms, unsigned int max_entries, gs_function_scheduler_t ** scheduler);
+
+/**
+   Free scheduler (release resources).
+   @param[in] scheduler scheduler.
+   @return_gs_error_t
+*/
+gs_error_t gs_function_scheduler_destroy(gs_function_scheduler_t * scheduler);
+
+/**
+   Execute scheduled function(s) and returns number of mS until next execute must be called again.
+
+   @note Return type is \a int to prevent overflow on platforms where int is less than 32 bits.
+
+   @param[in] scheduler scheduler.
+   @return next timeout in mS.
+*/
+int gs_function_scheduler_execute_ms(gs_function_scheduler_t * scheduler);
+
+/**
+   Register function to be executed at mS intervals.
+   @param[in] scheduler scheduler.
+   @param[in] first_timeout_ms mS until first execution.
+   @param[in] func function to execute.
+   @param[in] user_data function user data.
+   @return_gs_error_t
+*/
+gs_error_t gs_function_scheduler_register_ms(gs_function_scheduler_t * scheduler, uint32_t first_timeout_ms, gs_function_scheduler_function_t func, void * user_data);
+
+#ifdef __cplusplus
+}
+#endif
+#endif