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+/*
+ * FreeRTOS Kernel V10.1.1
+ * Copyright (C) 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * http://www.FreeRTOS.org
+ * http://aws.amazon.com/freertos
+ *
+ * 1 tab == 4 spaces!
+ */
+
+/*
+ * Stream buffers are used to send a continuous stream of data from one task or
+ * interrupt to another. Their implementation is light weight, making them
+ * particularly suited for interrupt to task and core to core communication
+ * scenarios.
+ *
+ * ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer
+ * implementation (so also the message buffer implementation, as message buffers
+ * are built on top of stream buffers) assumes there is only one task or
+ * interrupt that will write to the buffer (the writer), and only one task or
+ * interrupt that will read from the buffer (the reader). It is safe for the
+ * writer and reader to be different tasks or interrupts, but, unlike other
+ * FreeRTOS objects, it is not safe to have multiple different writers or
+ * multiple different readers. If there are to be multiple different writers
+ * then the application writer must place each call to a writing API function
+ * (such as xStreamBufferSend()) inside a critical section and set the send
+ * block time to 0. Likewise, if there are to be multiple different readers
+ * then the application writer must place each call to a reading API function
+ * (such as xStreamBufferRead()) inside a critical section section and set the
+ * receive block time to 0.
+ *
+ */
+
+#ifndef STREAM_BUFFER_H
+#define STREAM_BUFFER_H
+
+#if defined( __cplusplus )
+extern "C" {
+#endif
+
+/**
+ * Type by which stream buffers are referenced. For example, a call to
+ * xStreamBufferCreate() returns an StreamBufferHandle_t variable that can
+ * then be used as a parameter to xStreamBufferSend(), xStreamBufferReceive(),
+ * etc.
+ */
+struct StreamBufferDef_t;
+typedef struct StreamBufferDef_t * StreamBufferHandle_t;
+
+
+/**
+ * message_buffer.h
+ *
+<pre>
+StreamBufferHandle_t xStreamBufferCreate( size_t xBufferSizeBytes, size_t xTriggerLevelBytes );
+</pre>
+ *
+ * Creates a new stream buffer using dynamically allocated memory. See
+ * xStreamBufferCreateStatic() for a version that uses statically allocated
+ * memory (memory that is allocated at compile time).
+ *
+ * configSUPPORT_DYNAMIC_ALLOCATION must be set to 1 or left undefined in
+ * FreeRTOSConfig.h for xStreamBufferCreate() to be available.
+ *
+ * @param xBufferSizeBytes The total number of bytes the stream buffer will be
+ * able to hold at any one time.
+ *
+ * @param xTriggerLevelBytes The number of bytes that must be in the stream
+ * buffer before a task that is blocked on the stream buffer to wait for data is
+ * moved out of the blocked state. For example, if a task is blocked on a read
+ * of an empty stream buffer that has a trigger level of 1 then the task will be
+ * unblocked when a single byte is written to the buffer or the task's block
+ * time expires. As another example, if a task is blocked on a read of an empty
+ * stream buffer that has a trigger level of 10 then the task will not be
+ * unblocked until the stream buffer contains at least 10 bytes or the task's
+ * block time expires. If a reading task's block time expires before the
+ * trigger level is reached then the task will still receive however many bytes
+ * are actually available. Setting a trigger level of 0 will result in a
+ * trigger level of 1 being used. It is not valid to specify a trigger level
+ * that is greater than the buffer size.
+ *
+ * @return If NULL is returned, then the stream buffer cannot be created
+ * because there is insufficient heap memory available for FreeRTOS to allocate
+ * the stream buffer data structures and storage area. A non-NULL value being
+ * returned indicates that the stream buffer has been created successfully -
+ * the returned value should be stored as the handle to the created stream
+ * buffer.
+ *
+ * Example use:
+<pre>
+
+void vAFunction( void )
+{
+StreamBufferHandle_t xStreamBuffer;
+const size_t xStreamBufferSizeBytes = 100, xTriggerLevel = 10;
+
+ // Create a stream buffer that can hold 100 bytes. The memory used to hold
+ // both the stream buffer structure and the data in the stream buffer is
+ // allocated dynamically.
+ xStreamBuffer = xStreamBufferCreate( xStreamBufferSizeBytes, xTriggerLevel );
+
+ if( xStreamBuffer == NULL )
+ {
+ // There was not enough heap memory space available to create the
+ // stream buffer.
+ }
+ else
+ {
+ // The stream buffer was created successfully and can now be used.
+ }
+}
+</pre>
+ * \defgroup xStreamBufferCreate xStreamBufferCreate
+ * \ingroup StreamBufferManagement
+ */
+#define xStreamBufferCreate( xBufferSizeBytes, xTriggerLevelBytes ) xStreamBufferGenericCreate( xBufferSizeBytes, xTriggerLevelBytes, pdFALSE )
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+StreamBufferHandle_t xStreamBufferCreateStatic( size_t xBufferSizeBytes,
+ size_t xTriggerLevelBytes,
+ uint8_t *pucStreamBufferStorageArea,
+ StaticStreamBuffer_t *pxStaticStreamBuffer );
+</pre>
+ * Creates a new stream buffer using statically allocated memory. See
+ * xStreamBufferCreate() for a version that uses dynamically allocated memory.
+ *
+ * configSUPPORT_STATIC_ALLOCATION must be set to 1 in FreeRTOSConfig.h for
+ * xStreamBufferCreateStatic() to be available.
+ *
+ * @param xBufferSizeBytes The size, in bytes, of the buffer pointed to by the
+ * pucStreamBufferStorageArea parameter.
+ *
+ * @param xTriggerLevelBytes The number of bytes that must be in the stream
+ * buffer before a task that is blocked on the stream buffer to wait for data is
+ * moved out of the blocked state. For example, if a task is blocked on a read
+ * of an empty stream buffer that has a trigger level of 1 then the task will be
+ * unblocked when a single byte is written to the buffer or the task's block
+ * time expires. As another example, if a task is blocked on a read of an empty
+ * stream buffer that has a trigger level of 10 then the task will not be
+ * unblocked until the stream buffer contains at least 10 bytes or the task's
+ * block time expires. If a reading task's block time expires before the
+ * trigger level is reached then the task will still receive however many bytes
+ * are actually available. Setting a trigger level of 0 will result in a
+ * trigger level of 1 being used. It is not valid to specify a trigger level
+ * that is greater than the buffer size.
+ *
+ * @param pucStreamBufferStorageArea Must point to a uint8_t array that is at
+ * least xBufferSizeBytes + 1 big. This is the array to which streams are
+ * copied when they are written to the stream buffer.
+ *
+ * @param pxStaticStreamBuffer Must point to a variable of type
+ * StaticStreamBuffer_t, which will be used to hold the stream buffer's data
+ * structure.
+ *
+ * @return If the stream buffer is created successfully then a handle to the
+ * created stream buffer is returned. If either pucStreamBufferStorageArea or
+ * pxStaticstreamBuffer are NULL then NULL is returned.
+ *
+ * Example use:
+<pre>
+
+// Used to dimension the array used to hold the streams. The available space
+// will actually be one less than this, so 999.
+#define STORAGE_SIZE_BYTES 1000
+
+// Defines the memory that will actually hold the streams within the stream
+// buffer.
+static uint8_t ucStorageBuffer[ STORAGE_SIZE_BYTES ];
+
+// The variable used to hold the stream buffer structure.
+StaticStreamBuffer_t xStreamBufferStruct;
+
+void MyFunction( void )
+{
+StreamBufferHandle_t xStreamBuffer;
+const size_t xTriggerLevel = 1;
+
+ xStreamBuffer = xStreamBufferCreateStatic( sizeof( ucBufferStorage ),
+ xTriggerLevel,
+ ucBufferStorage,
+ &xStreamBufferStruct );
+
+ // As neither the pucStreamBufferStorageArea or pxStaticStreamBuffer
+ // parameters were NULL, xStreamBuffer will not be NULL, and can be used to
+ // reference the created stream buffer in other stream buffer API calls.
+
+ // Other code that uses the stream buffer can go here.
+}
+
+</pre>
+ * \defgroup xStreamBufferCreateStatic xStreamBufferCreateStatic
+ * \ingroup StreamBufferManagement
+ */
+#define xStreamBufferCreateStatic( xBufferSizeBytes, xTriggerLevelBytes, pucStreamBufferStorageArea, pxStaticStreamBuffer ) xStreamBufferGenericCreateStatic( xBufferSizeBytes, xTriggerLevelBytes, pdFALSE, pucStreamBufferStorageArea, pxStaticStreamBuffer )
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+size_t xStreamBufferSend( StreamBufferHandle_t xStreamBuffer,
+ const void *pvTxData,
+ size_t xDataLengthBytes,
+ TickType_t xTicksToWait );
+</pre>
+ *
+ * Sends bytes to a stream buffer. The bytes are copied into the stream buffer.
+ *
+ * ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer
+ * implementation (so also the message buffer implementation, as message buffers
+ * are built on top of stream buffers) assumes there is only one task or
+ * interrupt that will write to the buffer (the writer), and only one task or
+ * interrupt that will read from the buffer (the reader). It is safe for the
+ * writer and reader to be different tasks or interrupts, but, unlike other
+ * FreeRTOS objects, it is not safe to have multiple different writers or
+ * multiple different readers. If there are to be multiple different writers
+ * then the application writer must place each call to a writing API function
+ * (such as xStreamBufferSend()) inside a critical section and set the send
+ * block time to 0. Likewise, if there are to be multiple different readers
+ * then the application writer must place each call to a reading API function
+ * (such as xStreamBufferRead()) inside a critical section and set the receive
+ * block time to 0.
+ *
+ * Use xStreamBufferSend() to write to a stream buffer from a task. Use
+ * xStreamBufferSendFromISR() to write to a stream buffer from an interrupt
+ * service routine (ISR).
+ *
+ * @param xStreamBuffer The handle of the stream buffer to which a stream is
+ * being sent.
+ *
+ * @param pvTxData A pointer to the buffer that holds the bytes to be copied
+ * into the stream buffer.
+ *
+ * @param xDataLengthBytes The maximum number of bytes to copy from pvTxData
+ * into the stream buffer.
+ *
+ * @param xTicksToWait The maximum amount of time the task should remain in the
+ * Blocked state to wait for enough space to become available in the stream
+ * buffer, should the stream buffer contain too little space to hold the
+ * another xDataLengthBytes bytes. The block time is specified in tick periods,
+ * so the absolute time it represents is dependent on the tick frequency. The
+ * macro pdMS_TO_TICKS() can be used to convert a time specified in milliseconds
+ * into a time specified in ticks. Setting xTicksToWait to portMAX_DELAY will
+ * cause the task to wait indefinitely (without timing out), provided
+ * INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. If a task times out
+ * before it can write all xDataLengthBytes into the buffer it will still write
+ * as many bytes as possible. A task does not use any CPU time when it is in
+ * the blocked state.
+ *
+ * @return The number of bytes written to the stream buffer. If a task times
+ * out before it can write all xDataLengthBytes into the buffer it will still
+ * write as many bytes as possible.
+ *
+ * Example use:
+<pre>
+void vAFunction( StreamBufferHandle_t xStreamBuffer )
+{
+size_t xBytesSent;
+uint8_t ucArrayToSend[] = { 0, 1, 2, 3 };
+char *pcStringToSend = "String to send";
+const TickType_t x100ms = pdMS_TO_TICKS( 100 );
+
+ // Send an array to the stream buffer, blocking for a maximum of 100ms to
+ // wait for enough space to be available in the stream buffer.
+ xBytesSent = xStreamBufferSend( xStreamBuffer, ( void * ) ucArrayToSend, sizeof( ucArrayToSend ), x100ms );
+
+ if( xBytesSent != sizeof( ucArrayToSend ) )
+ {
+ // The call to xStreamBufferSend() times out before there was enough
+ // space in the buffer for the data to be written, but it did
+ // successfully write xBytesSent bytes.
+ }
+
+ // Send the string to the stream buffer. Return immediately if there is not
+ // enough space in the buffer.
+ xBytesSent = xStreamBufferSend( xStreamBuffer, ( void * ) pcStringToSend, strlen( pcStringToSend ), 0 );
+
+ if( xBytesSent != strlen( pcStringToSend ) )
+ {
+ // The entire string could not be added to the stream buffer because
+ // there was not enough free space in the buffer, but xBytesSent bytes
+ // were sent. Could try again to send the remaining bytes.
+ }
+}
+</pre>
+ * \defgroup xStreamBufferSend xStreamBufferSend
+ * \ingroup StreamBufferManagement
+ */
+size_t xStreamBufferSend( StreamBufferHandle_t xStreamBuffer,
+ const void *pvTxData,
+ size_t xDataLengthBytes,
+ TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+size_t xStreamBufferSendFromISR( StreamBufferHandle_t xStreamBuffer,
+ const void *pvTxData,
+ size_t xDataLengthBytes,
+ BaseType_t *pxHigherPriorityTaskWoken );
+</pre>
+ *
+ * Interrupt safe version of the API function that sends a stream of bytes to
+ * the stream buffer.
+ *
+ * ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer
+ * implementation (so also the message buffer implementation, as message buffers
+ * are built on top of stream buffers) assumes there is only one task or
+ * interrupt that will write to the buffer (the writer), and only one task or
+ * interrupt that will read from the buffer (the reader). It is safe for the
+ * writer and reader to be different tasks or interrupts, but, unlike other
+ * FreeRTOS objects, it is not safe to have multiple different writers or
+ * multiple different readers. If there are to be multiple different writers
+ * then the application writer must place each call to a writing API function
+ * (such as xStreamBufferSend()) inside a critical section and set the send
+ * block time to 0. Likewise, if there are to be multiple different readers
+ * then the application writer must place each call to a reading API function
+ * (such as xStreamBufferRead()) inside a critical section and set the receive
+ * block time to 0.
+ *
+ * Use xStreamBufferSend() to write to a stream buffer from a task. Use
+ * xStreamBufferSendFromISR() to write to a stream buffer from an interrupt
+ * service routine (ISR).
+ *
+ * @param xStreamBuffer The handle of the stream buffer to which a stream is
+ * being sent.
+ *
+ * @param pvTxData A pointer to the data that is to be copied into the stream
+ * buffer.
+ *
+ * @param xDataLengthBytes The maximum number of bytes to copy from pvTxData
+ * into the stream buffer.
+ *
+ * @param pxHigherPriorityTaskWoken It is possible that a stream buffer will
+ * have a task blocked on it waiting for data. Calling
+ * xStreamBufferSendFromISR() can make data available, and so cause a task that
+ * was waiting for data to leave the Blocked state. If calling
+ * xStreamBufferSendFromISR() causes a task to leave the Blocked state, and the
+ * unblocked task has a priority higher than the currently executing task (the
+ * task that was interrupted), then, internally, xStreamBufferSendFromISR()
+ * will set *pxHigherPriorityTaskWoken to pdTRUE. If
+ * xStreamBufferSendFromISR() sets this value to pdTRUE, then normally a
+ * context switch should be performed before the interrupt is exited. This will
+ * ensure that the interrupt returns directly to the highest priority Ready
+ * state task. *pxHigherPriorityTaskWoken should be set to pdFALSE before it
+ * is passed into the function. See the example code below for an example.
+ *
+ * @return The number of bytes actually written to the stream buffer, which will
+ * be less than xDataLengthBytes if the stream buffer didn't have enough free
+ * space for all the bytes to be written.
+ *
+ * Example use:
+<pre>
+// A stream buffer that has already been created.
+StreamBufferHandle_t xStreamBuffer;
+
+void vAnInterruptServiceRoutine( void )
+{
+size_t xBytesSent;
+char *pcStringToSend = "String to send";
+BaseType_t xHigherPriorityTaskWoken = pdFALSE; // Initialised to pdFALSE.
+
+ // Attempt to send the string to the stream buffer.
+ xBytesSent = xStreamBufferSendFromISR( xStreamBuffer,
+ ( void * ) pcStringToSend,
+ strlen( pcStringToSend ),
+ &xHigherPriorityTaskWoken );
+
+ if( xBytesSent != strlen( pcStringToSend ) )
+ {
+ // There was not enough free space in the stream buffer for the entire
+ // string to be written, ut xBytesSent bytes were written.
+ }
+
+ // If xHigherPriorityTaskWoken was set to pdTRUE inside
+ // xStreamBufferSendFromISR() then a task that has a priority above the
+ // priority of the currently executing task was unblocked and a context
+ // switch should be performed to ensure the ISR returns to the unblocked
+ // task. In most FreeRTOS ports this is done by simply passing
+ // xHigherPriorityTaskWoken into taskYIELD_FROM_ISR(), which will test the
+ // variables value, and perform the context switch if necessary. Check the
+ // documentation for the port in use for port specific instructions.
+ taskYIELD_FROM_ISR( xHigherPriorityTaskWoken );
+}
+</pre>
+ * \defgroup xStreamBufferSendFromISR xStreamBufferSendFromISR
+ * \ingroup StreamBufferManagement
+ */
+size_t xStreamBufferSendFromISR( StreamBufferHandle_t xStreamBuffer,
+ const void *pvTxData,
+ size_t xDataLengthBytes,
+ BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
+ void *pvRxData,
+ size_t xBufferLengthBytes,
+ TickType_t xTicksToWait );
+</pre>
+ *
+ * Receives bytes from a stream buffer.
+ *
+ * ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer
+ * implementation (so also the message buffer implementation, as message buffers
+ * are built on top of stream buffers) assumes there is only one task or
+ * interrupt that will write to the buffer (the writer), and only one task or
+ * interrupt that will read from the buffer (the reader). It is safe for the
+ * writer and reader to be different tasks or interrupts, but, unlike other
+ * FreeRTOS objects, it is not safe to have multiple different writers or
+ * multiple different readers. If there are to be multiple different writers
+ * then the application writer must place each call to a writing API function
+ * (such as xStreamBufferSend()) inside a critical section and set the send
+ * block time to 0. Likewise, if there are to be multiple different readers
+ * then the application writer must place each call to a reading API function
+ * (such as xStreamBufferRead()) inside a critical section and set the receive
+ * block time to 0.
+ *
+ * Use xStreamBufferReceive() to read from a stream buffer from a task. Use
+ * xStreamBufferReceiveFromISR() to read from a stream buffer from an
+ * interrupt service routine (ISR).
+ *
+ * @param xStreamBuffer The handle of the stream buffer from which bytes are to
+ * be received.
+ *
+ * @param pvRxData A pointer to the buffer into which the received bytes will be
+ * copied.
+ *
+ * @param xBufferLengthBytes The length of the buffer pointed to by the
+ * pvRxData parameter. This sets the maximum number of bytes to receive in one
+ * call. xStreamBufferReceive will return as many bytes as possible up to a
+ * maximum set by xBufferLengthBytes.
+ *
+ * @param xTicksToWait The maximum amount of time the task should remain in the
+ * Blocked state to wait for data to become available if the stream buffer is
+ * empty. xStreamBufferReceive() will return immediately if xTicksToWait is
+ * zero. The block time is specified in tick periods, so the absolute time it
+ * represents is dependent on the tick frequency. The macro pdMS_TO_TICKS() can
+ * be used to convert a time specified in milliseconds into a time specified in
+ * ticks. Setting xTicksToWait to portMAX_DELAY will cause the task to wait
+ * indefinitely (without timing out), provided INCLUDE_vTaskSuspend is set to 1
+ * in FreeRTOSConfig.h. A task does not use any CPU time when it is in the
+ * Blocked state.
+ *
+ * @return The number of bytes actually read from the stream buffer, which will
+ * be less than xBufferLengthBytes if the call to xStreamBufferReceive() timed
+ * out before xBufferLengthBytes were available.
+ *
+ * Example use:
+<pre>
+void vAFunction( StreamBuffer_t xStreamBuffer )
+{
+uint8_t ucRxData[ 20 ];
+size_t xReceivedBytes;
+const TickType_t xBlockTime = pdMS_TO_TICKS( 20 );
+
+ // Receive up to another sizeof( ucRxData ) bytes from the stream buffer.
+ // Wait in the Blocked state (so not using any CPU processing time) for a
+ // maximum of 100ms for the full sizeof( ucRxData ) number of bytes to be
+ // available.
+ xReceivedBytes = xStreamBufferReceive( xStreamBuffer,
+ ( void * ) ucRxData,
+ sizeof( ucRxData ),
+ xBlockTime );
+
+ if( xReceivedBytes > 0 )
+ {
+ // A ucRxData contains another xRecievedBytes bytes of data, which can
+ // be processed here....
+ }
+}
+</pre>
+ * \defgroup xStreamBufferReceive xStreamBufferReceive
+ * \ingroup StreamBufferManagement
+ */
+size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
+ void *pvRxData,
+ size_t xBufferLengthBytes,
+ TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+size_t xStreamBufferReceiveFromISR( StreamBufferHandle_t xStreamBuffer,
+ void *pvRxData,
+ size_t xBufferLengthBytes,
+ BaseType_t *pxHigherPriorityTaskWoken );
+</pre>
+ *
+ * An interrupt safe version of the API function that receives bytes from a
+ * stream buffer.
+ *
+ * Use xStreamBufferReceive() to read bytes from a stream buffer from a task.
+ * Use xStreamBufferReceiveFromISR() to read bytes from a stream buffer from an
+ * interrupt service routine (ISR).
+ *
+ * @param xStreamBuffer The handle of the stream buffer from which a stream
+ * is being received.
+ *
+ * @param pvRxData A pointer to the buffer into which the received bytes are
+ * copied.
+ *
+ * @param xBufferLengthBytes The length of the buffer pointed to by the
+ * pvRxData parameter. This sets the maximum number of bytes to receive in one
+ * call. xStreamBufferReceive will return as many bytes as possible up to a
+ * maximum set by xBufferLengthBytes.
+ *
+ * @param pxHigherPriorityTaskWoken It is possible that a stream buffer will
+ * have a task blocked on it waiting for space to become available. Calling
+ * xStreamBufferReceiveFromISR() can make space available, and so cause a task
+ * that is waiting for space to leave the Blocked state. If calling
+ * xStreamBufferReceiveFromISR() causes a task to leave the Blocked state, and
+ * the unblocked task has a priority higher than the currently executing task
+ * (the task that was interrupted), then, internally,
+ * xStreamBufferReceiveFromISR() will set *pxHigherPriorityTaskWoken to pdTRUE.
+ * If xStreamBufferReceiveFromISR() sets this value to pdTRUE, then normally a
+ * context switch should be performed before the interrupt is exited. That will
+ * ensure the interrupt returns directly to the highest priority Ready state
+ * task. *pxHigherPriorityTaskWoken should be set to pdFALSE before it is
+ * passed into the function. See the code example below for an example.
+ *
+ * @return The number of bytes read from the stream buffer, if any.
+ *
+ * Example use:
+<pre>
+// A stream buffer that has already been created.
+StreamBuffer_t xStreamBuffer;
+
+void vAnInterruptServiceRoutine( void )
+{
+uint8_t ucRxData[ 20 ];
+size_t xReceivedBytes;
+BaseType_t xHigherPriorityTaskWoken = pdFALSE; // Initialised to pdFALSE.
+
+ // Receive the next stream from the stream buffer.
+ xReceivedBytes = xStreamBufferReceiveFromISR( xStreamBuffer,
+ ( void * ) ucRxData,
+ sizeof( ucRxData ),
+ &xHigherPriorityTaskWoken );
+
+ if( xReceivedBytes > 0 )
+ {
+ // ucRxData contains xReceivedBytes read from the stream buffer.
+ // Process the stream here....
+ }
+
+ // If xHigherPriorityTaskWoken was set to pdTRUE inside
+ // xStreamBufferReceiveFromISR() then a task that has a priority above the
+ // priority of the currently executing task was unblocked and a context
+ // switch should be performed to ensure the ISR returns to the unblocked
+ // task. In most FreeRTOS ports this is done by simply passing
+ // xHigherPriorityTaskWoken into taskYIELD_FROM_ISR(), which will test the
+ // variables value, and perform the context switch if necessary. Check the
+ // documentation for the port in use for port specific instructions.
+ taskYIELD_FROM_ISR( xHigherPriorityTaskWoken );
+}
+</pre>
+ * \defgroup xStreamBufferReceiveFromISR xStreamBufferReceiveFromISR
+ * \ingroup StreamBufferManagement
+ */
+size_t xStreamBufferReceiveFromISR( StreamBufferHandle_t xStreamBuffer,
+ void *pvRxData,
+ size_t xBufferLengthBytes,
+ BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+void vStreamBufferDelete( StreamBufferHandle_t xStreamBuffer );
+</pre>
+ *
+ * Deletes a stream buffer that was previously created using a call to
+ * xStreamBufferCreate() or xStreamBufferCreateStatic(). If the stream
+ * buffer was created using dynamic memory (that is, by xStreamBufferCreate()),
+ * then the allocated memory is freed.
+ *
+ * A stream buffer handle must not be used after the stream buffer has been
+ * deleted.
+ *
+ * @param xStreamBuffer The handle of the stream buffer to be deleted.
+ *
+ * \defgroup vStreamBufferDelete vStreamBufferDelete
+ * \ingroup StreamBufferManagement
+ */
+void vStreamBufferDelete( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+BaseType_t xStreamBufferIsFull( StreamBufferHandle_t xStreamBuffer );
+</pre>
+ *
+ * Queries a stream buffer to see if it is full. A stream buffer is full if it
+ * does not have any free space, and therefore cannot accept any more data.
+ *
+ * @param xStreamBuffer The handle of the stream buffer being queried.
+ *
+ * @return If the stream buffer is full then pdTRUE is returned. Otherwise
+ * pdFALSE is returned.
+ *
+ * \defgroup xStreamBufferIsFull xStreamBufferIsFull
+ * \ingroup StreamBufferManagement
+ */
+BaseType_t xStreamBufferIsFull( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+BaseType_t xStreamBufferIsEmpty( StreamBufferHandle_t xStreamBuffer );
+</pre>
+ *
+ * Queries a stream buffer to see if it is empty. A stream buffer is empty if
+ * it does not contain any data.
+ *
+ * @param xStreamBuffer The handle of the stream buffer being queried.
+ *
+ * @return If the stream buffer is empty then pdTRUE is returned. Otherwise
+ * pdFALSE is returned.
+ *
+ * \defgroup xStreamBufferIsEmpty xStreamBufferIsEmpty
+ * \ingroup StreamBufferManagement
+ */
+BaseType_t xStreamBufferIsEmpty( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+BaseType_t xStreamBufferReset( StreamBufferHandle_t xStreamBuffer );
+</pre>
+ *
+ * Resets a stream buffer to its initial, empty, state. Any data that was in
+ * the stream buffer is discarded. A stream buffer can only be reset if there
+ * are no tasks blocked waiting to either send to or receive from the stream
+ * buffer.
+ *
+ * @param xStreamBuffer The handle of the stream buffer being reset.
+ *
+ * @return If the stream buffer is reset then pdPASS is returned. If there was
+ * a task blocked waiting to send to or read from the stream buffer then the
+ * stream buffer is not reset and pdFAIL is returned.
+ *
+ * \defgroup xStreamBufferReset xStreamBufferReset
+ * \ingroup StreamBufferManagement
+ */
+BaseType_t xStreamBufferReset( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+size_t xStreamBufferSpacesAvailable( StreamBufferHandle_t xStreamBuffer );
+</pre>
+ *
+ * Queries a stream buffer to see how much free space it contains, which is
+ * equal to the amount of data that can be sent to the stream buffer before it
+ * is full.
+ *
+ * @param xStreamBuffer The handle of the stream buffer being queried.
+ *
+ * @return The number of bytes that can be written to the stream buffer before
+ * the stream buffer would be full.
+ *
+ * \defgroup xStreamBufferSpacesAvailable xStreamBufferSpacesAvailable
+ * \ingroup StreamBufferManagement
+ */
+size_t xStreamBufferSpacesAvailable( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+size_t xStreamBufferBytesAvailable( StreamBufferHandle_t xStreamBuffer );
+</pre>
+ *
+ * Queries a stream buffer to see how much data it contains, which is equal to
+ * the number of bytes that can be read from the stream buffer before the stream
+ * buffer would be empty.
+ *
+ * @param xStreamBuffer The handle of the stream buffer being queried.
+ *
+ * @return The number of bytes that can be read from the stream buffer before
+ * the stream buffer would be empty.
+ *
+ * \defgroup xStreamBufferBytesAvailable xStreamBufferBytesAvailable
+ * \ingroup StreamBufferManagement
+ */
+size_t xStreamBufferBytesAvailable( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+BaseType_t xStreamBufferSetTriggerLevel( StreamBufferHandle_t xStreamBuffer, size_t xTriggerLevel );
+</pre>
+ *
+ * A stream buffer's trigger level is the number of bytes that must be in the
+ * stream buffer before a task that is blocked on the stream buffer to
+ * wait for data is moved out of the blocked state. For example, if a task is
+ * blocked on a read of an empty stream buffer that has a trigger level of 1
+ * then the task will be unblocked when a single byte is written to the buffer
+ * or the task's block time expires. As another example, if a task is blocked
+ * on a read of an empty stream buffer that has a trigger level of 10 then the
+ * task will not be unblocked until the stream buffer contains at least 10 bytes
+ * or the task's block time expires. If a reading task's block time expires
+ * before the trigger level is reached then the task will still receive however
+ * many bytes are actually available. Setting a trigger level of 0 will result
+ * in a trigger level of 1 being used. It is not valid to specify a trigger
+ * level that is greater than the buffer size.
+ *
+ * A trigger level is set when the stream buffer is created, and can be modified
+ * using xStreamBufferSetTriggerLevel().
+ *
+ * @param xStreamBuffer The handle of the stream buffer being updated.
+ *
+ * @param xTriggerLevel The new trigger level for the stream buffer.
+ *
+ * @return If xTriggerLevel was less than or equal to the stream buffer's length
+ * then the trigger level will be updated and pdTRUE is returned. Otherwise
+ * pdFALSE is returned.
+ *
+ * \defgroup xStreamBufferSetTriggerLevel xStreamBufferSetTriggerLevel
+ * \ingroup StreamBufferManagement
+ */
+BaseType_t xStreamBufferSetTriggerLevel( StreamBufferHandle_t xStreamBuffer, size_t xTriggerLevel ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+BaseType_t xStreamBufferSendCompletedFromISR( StreamBufferHandle_t xStreamBuffer, BaseType_t *pxHigherPriorityTaskWoken );
+</pre>
+ *
+ * For advanced users only.
+ *
+ * The sbSEND_COMPLETED() macro is called from within the FreeRTOS APIs when
+ * data is sent to a message buffer or stream buffer. If there was a task that
+ * was blocked on the message or stream buffer waiting for data to arrive then
+ * the sbSEND_COMPLETED() macro sends a notification to the task to remove it
+ * from the Blocked state. xStreamBufferSendCompletedFromISR() does the same
+ * thing. It is provided to enable application writers to implement their own
+ * version of sbSEND_COMPLETED(), and MUST NOT BE USED AT ANY OTHER TIME.
+ *
+ * See the example implemented in FreeRTOS/Demo/Minimal/MessageBufferAMP.c for
+ * additional information.
+ *
+ * @param xStreamBuffer The handle of the stream buffer to which data was
+ * written.
+ *
+ * @param pxHigherPriorityTaskWoken *pxHigherPriorityTaskWoken should be
+ * initialised to pdFALSE before it is passed into
+ * xStreamBufferSendCompletedFromISR(). If calling
+ * xStreamBufferSendCompletedFromISR() removes a task from the Blocked state,
+ * and the task has a priority above the priority of the currently running task,
+ * then *pxHigherPriorityTaskWoken will get set to pdTRUE indicating that a
+ * context switch should be performed before exiting the ISR.
+ *
+ * @return If a task was removed from the Blocked state then pdTRUE is returned.
+ * Otherwise pdFALSE is returned.
+ *
+ * \defgroup xStreamBufferSendCompletedFromISR xStreamBufferSendCompletedFromISR
+ * \ingroup StreamBufferManagement
+ */
+BaseType_t xStreamBufferSendCompletedFromISR( StreamBufferHandle_t xStreamBuffer, BaseType_t *pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION;
+
+/**
+ * stream_buffer.h
+ *
+<pre>
+BaseType_t xStreamBufferReceiveCompletedFromISR( StreamBufferHandle_t xStreamBuffer, BaseType_t *pxHigherPriorityTaskWoken );
+</pre>
+ *
+ * For advanced users only.
+ *
+ * The sbRECEIVE_COMPLETED() macro is called from within the FreeRTOS APIs when
+ * data is read out of a message buffer or stream buffer. If there was a task
+ * that was blocked on the message or stream buffer waiting for data to arrive
+ * then the sbRECEIVE_COMPLETED() macro sends a notification to the task to
+ * remove it from the Blocked state. xStreamBufferReceiveCompletedFromISR()
+ * does the same thing. It is provided to enable application writers to
+ * implement their own version of sbRECEIVE_COMPLETED(), and MUST NOT BE USED AT
+ * ANY OTHER TIME.
+ *
+ * See the example implemented in FreeRTOS/Demo/Minimal/MessageBufferAMP.c for
+ * additional information.
+ *
+ * @param xStreamBuffer The handle of the stream buffer from which data was
+ * read.
+ *
+ * @param pxHigherPriorityTaskWoken *pxHigherPriorityTaskWoken should be
+ * initialised to pdFALSE before it is passed into
+ * xStreamBufferReceiveCompletedFromISR(). If calling
+ * xStreamBufferReceiveCompletedFromISR() removes a task from the Blocked state,
+ * and the task has a priority above the priority of the currently running task,
+ * then *pxHigherPriorityTaskWoken will get set to pdTRUE indicating that a
+ * context switch should be performed before exiting the ISR.
+ *
+ * @return If a task was removed from the Blocked state then pdTRUE is returned.
+ * Otherwise pdFALSE is returned.
+ *
+ * \defgroup xStreamBufferReceiveCompletedFromISR xStreamBufferReceiveCompletedFromISR
+ * \ingroup StreamBufferManagement
+ */
+BaseType_t xStreamBufferReceiveCompletedFromISR( StreamBufferHandle_t xStreamBuffer, BaseType_t *pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION;
+
+/* Functions below here are not part of the public API. */
+StreamBufferHandle_t xStreamBufferGenericCreate( size_t xBufferSizeBytes,
+ size_t xTriggerLevelBytes,
+ BaseType_t xIsMessageBuffer ) PRIVILEGED_FUNCTION;
+
+StreamBufferHandle_t xStreamBufferGenericCreateStatic( size_t xBufferSizeBytes,
+ size_t xTriggerLevelBytes,
+ BaseType_t xIsMessageBuffer,
+ uint8_t * const pucStreamBufferStorageArea,
+ StaticStreamBuffer_t * const pxStaticStreamBuffer ) PRIVILEGED_FUNCTION;
+
+size_t xStreamBufferNextMessageLengthBytes( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+
+#if( configUSE_TRACE_FACILITY == 1 )
+ void vStreamBufferSetStreamBufferNumber( StreamBufferHandle_t xStreamBuffer, UBaseType_t uxStreamBufferNumber ) PRIVILEGED_FUNCTION;
+ UBaseType_t uxStreamBufferGetStreamBufferNumber( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+ uint8_t ucStreamBufferGetStreamBufferType( StreamBufferHandle_t xStreamBuffer ) PRIVILEGED_FUNCTION;
+#endif
+
+#if defined( __cplusplus )
+}
+#endif
+
+#endif /* !defined( STREAM_BUFFER_H ) */
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