canardTxPeek now returns mutable item
#236
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| /// The memory resource used by this queue for allocating the enqueued items (CAN frames). | ||
| /// There is exactly one allocation per enqueued item, each allocation contains both the CanardTxQueueItem | ||
| /// and its payload, hence the size is variable. | ||
| /// The memory resource used by this queue for allocating payload data (CAN frames). |
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the
(also check "with additional amount parameter" above)
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the
Sorry, did not get exactly what is missing for "the" comment. Could you please help?
The amount will be fixed by -> size - thnx!
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I mean the "the" article is missing
| /// There is exactly one allocation per enqueued item, each allocation contains both the CanardTxQueueItem | ||
| /// and its payload, hence the size is variable. | ||
| /// The memory resource used by this queue for allocating payload data (CAN frames). | ||
| /// There is exactly one allocation per enqueued item. Its size is equal to the MTU of the queue. |
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The first sentence is no longer applicable -- there are two allocations, not one. I would remove it
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I wrote this sentence specifically about this memory resource of the CanardTxQueue - from it we allocate once per enqueued item (not considering item itself b/c it is allocated from the instance resource).
What about the following variant?
/// The memory resource used by this queue for allocating payload data (CAN frames).
/// There is exactly one allocation of payload buffer per enqueued item (not considering the item itself
/// b/c it is allocated from different memory resource - the instance one; seeCanardInstance::memory).
libcanard/canard.h
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| /// If the application knows its MTU, it can use block allocation to avoid extrinsic fragmentation, | ||
| /// as well as a dedicated memory pool specifically for the TX queue payload for transmission. | ||
| /// Dedicated memory resources could be useful also for systems with special memory requirements for payload data. | ||
| /// For example, such a memory resource could be integrated with a peripheral DMA controller. So that |
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| /// For example, such a memory resource could be integrated with a peripheral DMA controller. So that | |
| /// For example, such a memory resource could be integrated with the CAN message RAM. So that |
This is more representative of the actual state of affairs with CAN FD controllers. Usually you have a separate memory region that is accessible both to the core and to the CAN controller peripheral. You find a free slot (usually with the help of a separate register), write the message into it, then signal the controller when it's ready to go.
libcanard/canard.h
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| /// Dedicated memory resources could be useful also for systems with special memory requirements for payload data. | ||
| /// For example, such a memory resource could be integrated with a peripheral DMA controller. So that | ||
| /// memory is allocated directly in the peripheral's memory space. Then it will be filled with payload data by | ||
| /// the Canard, and finally it will be ready to be directly transmitted by DMA HW (avoiding the need for copying). |
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| /// the Canard, and finally it will be ready to be directly transmitted by DMA HW (avoiding the need for copying). | |
| /// the Canard, and finally it will be ready to be directly transmitted by the HW (avoiding the need for copying). |
libcanard/canard.h
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| @@ -539,28 +553,43 @@ int32_t canardTxPush(CanardTxQueue* const que, | |||
| /// | |||
| /// If the queue is non-empty, the returned value is a pointer to its top element (i.e., the next frame to transmit). | |||
| /// The returned pointer points to an object allocated in the dynamic storage; it should be eventually freed by the | |||
| /// application by calling CanardInstance::memory_free(). The memory shall not be freed before the entry is removed | |||
| /// application by calling `udpardTxFree`. The memory shall not be freed before the entry is removed | |||
libcanard/canard.h
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| /// as well as the internal frame payload buffer (if any) associated with it (using TX queue memory). | ||
| /// If the item argument is NULL, the function has no effect. The time complexity is constant. | ||
| /// If the item frame payload is NULL then it is assumed that the payload buffer was already freed, | ||
| /// or moved to different ownership (f.e. to media layer). |
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| /// or moved to different ownership (f.e. to media layer). | |
| /// or moved to a different owner (f.e. to media layer). |
|
canardTxPeeknow returns mutable item - needed for payload ownership transfer.