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/*
* FreeRTOS Kernel V10.5.1
* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* SPDX-License-Identifier: MIT
*
* 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.
*
* https://www.FreeRTOS.org
* https://github.com/FreeRTOS
*
*/
/*
* 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 xStreamBufferReceive()) inside a critical section section and set the
* receive block time to 0.
*
*/
#ifndef STREAM_BUFFER_H
#define STREAM_BUFFER_H
#ifndef INC_FREERTOS_H
#error "include FreeRTOS.h must appear in source files before include stream_buffer.h"
#endif
/* *INDENT-OFF* */
#if defined( __cplusplus )
extern "C" {
#endif
/* *INDENT-ON* */
/**
* 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;
/**
* Type used as a stream buffer's optional callback.
*/
typedef void (* StreamBufferCallbackFunction_t)( StreamBufferHandle_t xStreamBuffer,
BaseType_t xIsInsideISR,
BaseType_t * const pxHigherPriorityTaskWoken );
/**
* stream_buffer.h
*
* @code{c}
* StreamBufferHandle_t xStreamBufferCreate( size_t xBufferSizeBytes, size_t xTriggerLevelBytes );
* @endcode
*
* 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.
*
* @param pxSendCompletedCallback Callback invoked when number of bytes at least equal to
* trigger level is sent to the stream buffer. If the parameter is NULL, it will use the default
* implementation provided by sbSEND_COMPLETED macro. To enable the callback,
* configUSE_SB_COMPLETED_CALLBACK must be set to 1 in FreeRTOSConfig.h.
*
* @param pxReceiveCompletedCallback Callback invoked when more than zero bytes are read from a
* stream buffer. If the parameter is NULL, it will use the default
* implementation provided by sbRECEIVE_COMPLETED macro. To enable the callback,
* configUSE_SB_COMPLETED_CALLBACK must be set to 1 in FreeRTOSConfig.h.
*
* @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:
* @code{c}
*
* 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.
* }
* }
* @endcode
* \defgroup xStreamBufferCreate xStreamBufferCreate
* \ingroup StreamBufferManagement
*/
#define xStreamBufferCreate( xBufferSizeBytes, xTriggerLevelBytes ) \
xStreamBufferGenericCreate( ( xBufferSizeBytes ), ( xTriggerLevelBytes ), pdFALSE, NULL, NULL )
#if ( configUSE_SB_COMPLETED_CALLBACK == 1 )
#define xStreamBufferCreateWithCallback( xBufferSizeBytes, xTriggerLevelBytes, pxSendCompletedCallback, pxReceiveCompletedCallback ) \
xStreamBufferGenericCreate( ( xBufferSizeBytes ), ( xTriggerLevelBytes ), pdFALSE, ( pxSendCompletedCallback ), ( pxReceiveCompletedCallback ) )
#endif
/**
* stream_buffer.h
*
* @code{c}
* StreamBufferHandle_t xStreamBufferCreateStatic( size_t xBufferSizeBytes,
* size_t xTriggerLevelBytes,
* uint8_t *pucStreamBufferStorageArea,
* StaticStreamBuffer_t *pxStaticStreamBuffer );
* @endcode
* 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 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.
*
* @param pxSendCompletedCallback Callback invoked when number of bytes at least equal to
* trigger level is sent to the stream buffer. If the parameter is NULL, it will use the default
* implementation provided by sbSEND_COMPLETED macro. To enable the callback,
* configUSE_SB_COMPLETED_CALLBACK must be set to 1 in FreeRTOSConfig.h.
*
* @param pxReceiveCompletedCallback Callback invoked when more than zero bytes are read from a
* stream buffer. If the parameter is NULL, it will use the default
* implementation provided by sbRECEIVE_COMPLETED macro. To enable the callback,
* configUSE_SB_COMPLETED_CALLBACK must be set to 1 in FreeRTOSConfig.h.
*
* @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:
* @code{c}
*
* // 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( ucStorageBuffer ),
* xTriggerLevel,
* ucStorageBuffer,
* &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.
* }
*
* @endcode
* \defgroup xStreamBufferCreateStatic xStreamBufferCreateStatic
* \ingroup StreamBufferManagement
*/
#define xStreamBufferCreateStatic( xBufferSizeBytes, xTriggerLevelBytes, pucStreamBufferStorageArea, pxStaticStreamBuffer ) \
xStreamBufferGenericCreateStatic( ( xBufferSizeBytes ), ( xTriggerLevelBytes ), pdFALSE, ( pucStreamBufferStorageArea ), ( pxStaticStreamBuffer ), NULL, NULL )
#if ( configUSE_SB_COMPLETED_CALLBACK == 1 )
#define xStreamBufferCreateStaticWithCallback( xBufferSizeBytes, xTriggerLevelBytes, pucStreamBufferStorageArea, pxStaticStreamBuffer, pxSendCompletedCallback, pxReceiveCompletedCallback ) \
xStreamBufferGenericCreateStatic( ( xBufferSizeBytes ), ( xTriggerLevelBytes ), pdFALSE, ( pucStreamBufferStorageArea ), ( pxStaticStreamBuffer ), ( pxSendCompletedCallback ), ( pxReceiveCompletedCallback ) )
#endif
/**
* stream_buffer.h
*
* @code{c}
* size_t xStreamBufferSend( StreamBufferHandle_t xStreamBuffer,
* const void *pvTxData,
* size_t xDataLengthBytes,
* TickType_t xTicksToWait );
* @endcode
*
* 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 xStreamBufferReceive()) 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:
* @code{c}
* 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.
* }
* }
* @endcode
* \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
*
* @code{c}
* size_t xStreamBufferSendFromISR( StreamBufferHandle_t xStreamBuffer,
* const void *pvTxData,
* size_t xDataLengthBytes,
* BaseType_t *pxHigherPriorityTaskWoken );
* @endcode
*
* 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 xStreamBufferReceive()) 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:
* @code{c}
* // 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 portYIELD_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.
* portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
* }
* @endcode
* \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
*
* @code{c}
* size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
* void *pvRxData,
* size_t xBufferLengthBytes,
* TickType_t xTicksToWait );
* @endcode
*
* 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 xStreamBufferReceive()) 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:
* @code{c}
* 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 xReceivedBytes bytes of data, which can
* // be processed here....
* }
* }
* @endcode
* \defgroup xStreamBufferReceive xStreamBufferReceive
* \ingroup StreamBufferManagement
*/
size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
void * pvRxData,
size_t xBufferLengthBytes,
TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
/**
* stream_buffer.h
*
* @code{c}
* size_t xStreamBufferReceiveFromISR( StreamBufferHandle_t xStreamBuffer,
* void *pvRxData,
* size_t xBufferLengthBytes,
* BaseType_t *pxHigherPriorityTaskWoken );
* @endcode
*
* 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:
* @code{c}
* // 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 portYIELD_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.
* portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
* }
* @endcode
* \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
*
* @code{c}
* void vStreamBufferDelete( StreamBufferHandle_t xStreamBuffer );
* @endcode
*
* 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
*
* @code{c}
* BaseType_t xStreamBufferIsFull( StreamBufferHandle_t xStreamBuffer );
* @endcode
*
* 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
*
* @code{c}
* BaseType_t xStreamBufferIsEmpty( StreamBufferHandle_t xStreamBuffer );
* @endcode
*
* 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
*
* @code{c}
* BaseType_t xStreamBufferReset( StreamBufferHandle_t xStreamBuffer );
* @endcode
*
* 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
*
* @code{c}
* size_t xStreamBufferSpacesAvailable( StreamBufferHandle_t xStreamBuffer );
* @endcode
*
* 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
*
* @code{c}
* size_t xStreamBufferBytesAvailable( StreamBufferHandle_t xStreamBuffer );
* @endcode
*
* 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
*
* @code{c}
* BaseType_t xStreamBufferSetTriggerLevel( StreamBufferHandle_t xStreamBuffer, size_t xTriggerLevel );
* @endcode
*
* 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
*
* @code{c}
* BaseType_t xStreamBufferSendCompletedFromISR( StreamBufferHandle_t xStreamBuffer, BaseType_t *pxHigherPriorityTaskWoken );
* @endcode
*
* 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
*
* @code{c}
* BaseType_t xStreamBufferReceiveCompletedFromISR( StreamBufferHandle_t xStreamBuffer, BaseType_t *pxHigherPriorityTaskWoken );
* @endcode
*
* 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,
StreamBufferCallbackFunction_t pxSendCompletedCallback,
StreamBufferCallbackFunction_t pxReceiveCompletedCallback ) PRIVILEGED_FUNCTION;
StreamBufferHandle_t xStreamBufferGenericCreateStatic( size_t xBufferSizeBytes,
size_t xTriggerLevelBytes,
BaseType_t xIsMessageBuffer,
uint8_t * const pucStreamBufferStorageArea,
StaticStreamBuffer_t * const pxStaticStreamBuffer,
StreamBufferCallbackFunction_t pxSendCompletedCallback,
StreamBufferCallbackFunction_t pxReceiveCompletedCallback ) 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
/* *INDENT-OFF* */
#if defined( __cplusplus )
}
#endif
/* *INDENT-ON* */
#endif /* !defined( STREAM_BUFFER_H ) */
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