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Merge pull request #6003 from miri64/core/doc/msg-init-queue-power-of-two

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doc: make the 2^x requirement for msg_queue more visible
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Peter Kietzmann 2016-11-01 12:16:09 +01:00 committed by GitHub
commit 11a8969ab0
2 changed files with 9 additions and 6 deletions
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12
core/include/msg.h
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@ -98,11 +98,11 @@
* Asynchronous IPC * Asynchronous IPC
* ---------------- * ----------------
* To use asynchronous IPC one needs to initialize a message queue using * To use asynchronous IPC one needs to initialize a message queue using
* @ref msg_init_queue(). Messages sent to a thread with a message queue that * @ref msg_init_queue() (note that it **must** be of a size equal to a power of
* isn't full are never dropped and the sending never blocks, even when using * two). Messages sent to a thread with a message queue that isn't full are
* @ref msg_send(). If the queue is full and the sending thread has a higher * never dropped and the sending never blocks, even when using @ref msg_send().
* priority than the receiving thread the send-behavior is equivalent to * If the queue is full and the sending thread has a higher priority than the
* synchronous mode. * receiving thread the send-behavior is equivalent to synchronous mode.
* *
* ~~~~~~~~~~~~~~~~~~~~~~~~ {.c} * ~~~~~~~~~~~~~~~~~~~~~~~~ {.c}
* #include <inttypes.h> * #include <inttypes.h>
@ -365,6 +365,8 @@ int msg_avail(void);
/** /**
* @brief Initialize the current thread's message queue. * @brief Initialize the current thread's message queue.
* *
* @pre @p num **MUST BE A POWER OF TWO!**
*
* @param[in] array Pointer to preallocated array of ``msg_t`` structures, must * @param[in] array Pointer to preallocated array of ``msg_t`` structures, must
* not be NULL. * not be NULL.
* @param[in] num Number of ``msg_t`` structures in array. * @param[in] num Number of ``msg_t`` structures in array.

3
sys/include/net/gnrc.h
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@ -55,7 +55,8 @@
* Hence, a thread for @ref net_gnrc "GNRC" will usually consist of four basic * Hence, a thread for @ref net_gnrc "GNRC" will usually consist of four basic
* steps. * steps.
* *
* 1. Initialize a message queue * 1. Initialize a message queue (note that its size **must** be a power of two,
* see @ref msg_init_queue())
* 2. register for a @ref net_gnrc_nettype * 2. register for a @ref net_gnrc_nettype
* 3. wait for a message * 3. wait for a message
* 4. react appropriately to a message and return to 3. * 4. react appropriately to a message and return to 3.