207 lines
7.8 KiB
C
207 lines
7.8 KiB
C
#ifndef FREERTOS_RINGBUF_H
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#define FREERTOS_RINGBUF_H
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/*
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Header definitions for a FreeRTOS ringbuffer object
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A ringbuffer instantiated by these functions essentially acts like a FreeRTOS queue, with the
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difference that it's strictly FIFO and with the main advantage that you can put in randomly-sized
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items. The capacity, accordingly, isn't measured in the amount of items, but the amount of memory
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that is used for storing the items. Dependent on the size of the items, more or less of them will
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fit in the ring buffer.
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This ringbuffer tries to be efficient with memory: when inserting an item, the item data will
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be copied to the ringbuffer memory. When retrieving an item, however, a reference to ringbuffer
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memory will be returned. The returned memory is guaranteed to be 32-bit aligned and contiguous.
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The application can use this memory, but as long as it does, ringbuffer writes that would write
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to this bit of memory will block.
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The requirement for items to be contiguous is slightly problematic when the only way to place
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the next item would involve a wraparound from the end to the beginning of the ringbuffer. This can
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be solved in two ways:
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- allow_split_items = pdTRUE: The insertion code will split the item in two items; one which fits
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in the space left at the end of the ringbuffer, one that contains the remaining data which is placed
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in the beginning. Two xRingbufferReceive calls will be needed to retrieve the data.
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- allow_split_items = pdFALSE: The insertion code will leave the room at the end of the ringbuffer
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unused and instead will put the entire item at the start of the ringbuffer, as soon as there is
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enough free space.
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The maximum size of an item will be affected by this decision. When split items are allowed, it's
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acceptable to push items of (buffer_size)-16 bytes into the buffer. When it's not allowed, the
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maximum size is (buffer_size/2)-8 bytes.
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*/
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//An opaque handle for a ringbuff object.
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typedef void * RingbufHandle_t;
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/**
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* @brief Create a ring buffer
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*
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* @param buf_length : Length of circular buffer, in bytes. Each entry will take up its own length, plus a header
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* that at the moment is equal to sizeof(size_t).
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* @param allow_split_items : pdTRUE if it is acceptable that item data is inserted as two
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* items instead of one.
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*
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* @return A RingbufHandle_t handle to the created ringbuffer, or NULL in case of error.
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*/
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RingbufHandle_t xRingbufferCreate(size_t buf_length, BaseType_t allow_split_items);
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/**
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* @brief Delete a ring buffer
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*
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* @param ringbuf - Ring buffer to delete
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*
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* @return void
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*/
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void vRingbufferDelete(RingbufHandle_t ringbuf);
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/**
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* @brief Get maximum size of an item that can be placed in the ring buffer
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*
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* @param ringbuf - Ring buffer to query
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*
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* @return Maximum size, in bytes, of an item that can be placed in a ring buffer.
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*/
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size_t xRingbufferGetMaxItemSize(RingbufHandle_t ringbuf);
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/**
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* @brief Insert an item into the ring buffer
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*
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* @param ringbuf - Ring buffer to insert the item into
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* @param data - Pointer to data to insert. NULL is allowed if data_size is 0.
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* @param data_size - Size of data to insert. A value of 0 is allowed.
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* @param xTicksToWait - Ticks to wait for room in the ringbuffer.
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*
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* @return pdTRUE if succeeded, pdFALSE on time-out or when the buffer is larger
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* than indicated by xRingbufferGetMaxItemSize(ringbuf).
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*/
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BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t data_size, TickType_t ticks_to_wait);
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/**
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* @brief Insert an item into the ring buffer from an ISR
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*
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* @param ringbuf - Ring buffer to insert the item into
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* @param data - Pointer to data to insert. NULL is allowed if data_size is 0.
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* @param data_size - Size of data to insert. A value of 0 is allowed.
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* @param higher_prio_task_awoken - Value pointed to will be set to pdTRUE if the push woke up a higher
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* priority task.
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*
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* @return pdTRUE if succeeded, pdFALSE when the ring buffer does not have space.
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*/
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BaseType_t xRingbufferSendFromISR(RingbufHandle_t ringbuf, void *data, size_t data_size, BaseType_t *higher_prio_task_awoken);
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/**
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* @brief Retrieve an item from the ring buffer
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*
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* @param ringbuf - Ring buffer to retrieve the item from
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* @param item_size - Pointer to a variable to which the size of the retrieved item will be written.
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* @param xTicksToWait - Ticks to wait for items in the ringbuffer.
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*
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* @return Pointer to the retrieved item on success; *item_size filled with the length of the
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* item. NULL on timeout, *item_size is untouched in that case.
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*/
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void *xRingbufferReceive(RingbufHandle_t ringbuf, size_t *item_size, TickType_t ticks_to_wait);
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/**
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* @brief Retrieve an item from the ring buffer from an ISR
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*
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* @param ringbuf - Ring buffer to retrieve the item from
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* @param item_size - Pointer to a variable to which the size of the retrieved item will be written.
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*
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* @return Pointer to the retrieved item on success; *item_size filled with the length of the
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* item. NULL when the ringbuffer is empty, *item_size is untouched in that case.
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*/
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void *xRingbufferReceiveFromISR(RingbufHandle_t ringbuf, size_t *item_size);
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/**
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* @brief Return a previously-retrieved item to the ringbuffer
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*
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* @param ringbuf - Ring buffer the item was retrieved from
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* @param item - Item that was received earlier
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*
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* @return void
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*/
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void vRingbufferReturnItem(RingbufHandle_t ringbuf, void *item);
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/**
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* @brief Return a previously-retrieved item to the ringbuffer from an ISR
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*
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* @param ringbuf - Ring buffer the item was retrieved from
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* @param item - Item that was received earlier
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* @param higher_prio_task_awoken - Value pointed to will be set to pdTRUE if the push woke up a higher
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* priority task.
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*
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* @return void
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*/
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void vRingbufferReturnItemFromISR(RingbufHandle_t ringbuf, void *item, BaseType_t *higher_prio_task_awoken);
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/**
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* @brief Add the ringbuffer to a queue set. This specifically adds the semaphore that indicates
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* more space has become available in the ringbuffer.
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*
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* @param ringbuf - Ring buffer to add to the queue set
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* @param xQueueSet - Queue set to add the ringbuffer to
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*
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* @return pdTRUE on success, pdFALSE otherwise
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*/
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BaseType_t xRingbufferAddToQueueSetRead(RingbufHandle_t ringbuf, QueueSetHandle_t xQueueSet);
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/**
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* @brief Add the ringbuffer to a queue set. This specifically adds the semaphore that indicates
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* something has been written into the ringbuffer.
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*
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* @param ringbuf - Ring buffer to add to the queue set
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* @param xQueueSet - Queue set to add the ringbuffer to
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*
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* @return pdTRUE on success, pdFALSE otherwise
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*/
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BaseType_t xRingbufferAddToQueueSetWrite(RingbufHandle_t ringbuf, QueueSetHandle_t xQueueSet);
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/**
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* @brief Remove the ringbuffer from a queue set. This specifically removes the semaphore that indicates
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* more space has become available in the ringbuffer.
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*
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* @param ringbuf - Ring buffer to remove from the queue set
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* @param xQueueSet - Queue set to remove the ringbuffer from
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*
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* @return pdTRUE on success, pdFALSE otherwise
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*/
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BaseType_t xRingbufferRemoveFromQueueSetRead(RingbufHandle_t ringbuf, QueueSetHandle_t xQueueSet);
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/**
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* @brief Remove the ringbuffer from a queue set. This specifically removes the semaphore that indicates
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* something has been written to the ringbuffer.
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*
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* @param ringbuf - Ring buffer to remove from the queue set
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* @param xQueueSet - Queue set to remove the ringbuffer from
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*
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* @return pdTRUE on success, pdFALSE otherwise
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*/
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BaseType_t xRingbufferRemoveFromQueueSetWrite(RingbufHandle_t ringbuf, QueueSetHandle_t xQueueSet);
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/**
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* @brief Debugging function to print the internal pointers in the ring buffer
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*
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* @param ringbuf - Ring buffer to show
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*
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* @return void
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*/
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void xRingbufferPrintInfo(RingbufHandle_t ringbuf);
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#endif
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