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859 lines
38 KiB
859 lines
38 KiB
/* |
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* FreeRTOS Kernel V10.3.1 |
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* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining a copy of |
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* this software and associated documentation files (the "Software"), to deal in |
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* the Software without restriction, including without limitation the rights to |
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of |
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* the Software, and to permit persons to whom the Software is furnished to do so, |
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* subject to the following conditions: |
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* |
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* The above copyright notice and this permission notice shall be included in all |
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* copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS |
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR |
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER |
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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* |
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* http://www.FreeRTOS.org |
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* http://aws.amazon.com/freertos |
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* |
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* 1 tab == 4 spaces! |
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*/ |
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|
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/* |
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* Stream buffers are used to send a continuous stream of data from one task or |
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* interrupt to another. Their implementation is light weight, making them |
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* particularly suited for interrupt to task and core to core communication |
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* scenarios. |
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* |
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* ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer |
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* implementation (so also the message buffer implementation, as message buffers |
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* are built on top of stream buffers) assumes there is only one task or |
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* interrupt that will write to the buffer (the writer), and only one task or |
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* interrupt that will read from the buffer (the reader). It is safe for the |
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* writer and reader to be different tasks or interrupts, but, unlike other |
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* FreeRTOS objects, it is not safe to have multiple different writers or |
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* multiple different readers. If there are to be multiple different writers |
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* then the application writer must place each call to a writing API function |
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* (such as xStreamBufferSend()) inside a critical section and set the send |
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* block time to 0. Likewise, if there are to be multiple different readers |
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* then the application writer must place each call to a reading API function |
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* (such as xStreamBufferReceive()) inside a critical section section and set the |
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* receive block time to 0. |
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* |
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*/ |
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|
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#ifndef STREAM_BUFFER_H |
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#define STREAM_BUFFER_H |
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|
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#ifndef INC_FREERTOS_H |
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#error "include FreeRTOS.h must appear in source files before include stream_buffer.h" |
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#endif |
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|
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#if defined( __cplusplus ) |
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extern "C" { |
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#endif |
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|
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/** |
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* Type by which stream buffers are referenced. For example, a call to |
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* xStreamBufferCreate() returns an StreamBufferHandle_t variable that can |
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* then be used as a parameter to xStreamBufferSend(), xStreamBufferReceive(), |
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* etc. |
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*/ |
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struct StreamBufferDef_t; |
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typedef struct StreamBufferDef_t * StreamBufferHandle_t; |
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|
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/** |
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* message_buffer.h |
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* |
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<pre> |
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StreamBufferHandle_t xStreamBufferCreate( size_t xBufferSizeBytes, size_t xTriggerLevelBytes ); |
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</pre> |
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* |
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* Creates a new stream buffer using dynamically allocated memory. See |
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* xStreamBufferCreateStatic() for a version that uses statically allocated |
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* memory (memory that is allocated at compile time). |
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* |
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* configSUPPORT_DYNAMIC_ALLOCATION must be set to 1 or left undefined in |
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* FreeRTOSConfig.h for xStreamBufferCreate() to be available. |
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* |
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* @param xBufferSizeBytes The total number of bytes the stream buffer will be |
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* able to hold at any one time. |
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* |
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* @param xTriggerLevelBytes The number of bytes that must be in the stream |
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* buffer before a task that is blocked on the stream buffer to wait for data is |
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* moved out of the blocked state. For example, if a task is blocked on a read |
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* of an empty stream buffer that has a trigger level of 1 then the task will be |
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* unblocked when a single byte is written to the buffer or the task's block |
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* time expires. As another example, if a task is blocked on a read of an empty |
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* stream buffer that has a trigger level of 10 then the task will not be |
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* unblocked until the stream buffer contains at least 10 bytes or the task's |
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* block time expires. If a reading task's block time expires before the |
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* trigger level is reached then the task will still receive however many bytes |
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* are actually available. Setting a trigger level of 0 will result in a |
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* trigger level of 1 being used. It is not valid to specify a trigger level |
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* that is greater than the buffer size. |
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* |
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* @return If NULL is returned, then the stream buffer cannot be created |
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* because there is insufficient heap memory available for FreeRTOS to allocate |
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* the stream buffer data structures and storage area. A non-NULL value being |
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* returned indicates that the stream buffer has been created successfully - |
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* the returned value should be stored as the handle to the created stream |
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* buffer. |
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* |
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* Example use: |
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<pre> |
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|
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void vAFunction( void ) |
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{ |
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StreamBufferHandle_t xStreamBuffer; |
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const size_t xStreamBufferSizeBytes = 100, xTriggerLevel = 10; |
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|
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// Create a stream buffer that can hold 100 bytes. The memory used to hold |
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// both the stream buffer structure and the data in the stream buffer is |
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// allocated dynamically. |
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xStreamBuffer = xStreamBufferCreate( xStreamBufferSizeBytes, xTriggerLevel ); |
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|
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if( xStreamBuffer == NULL ) |
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{ |
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// There was not enough heap memory space available to create the |
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// stream buffer. |
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} |
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else |
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{ |
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// The stream buffer was created successfully and can now be used. |
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} |
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} |
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</pre> |
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* \defgroup xStreamBufferCreate xStreamBufferCreate |
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* \ingroup StreamBufferManagement |
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*/ |
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#define xStreamBufferCreate( xBufferSizeBytes, xTriggerLevelBytes ) xStreamBufferGenericCreate( xBufferSizeBytes, xTriggerLevelBytes, pdFALSE ) |
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|
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/** |
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* stream_buffer.h |
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* |
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<pre> |
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StreamBufferHandle_t xStreamBufferCreateStatic( size_t xBufferSizeBytes, |
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size_t xTriggerLevelBytes, |
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uint8_t *pucStreamBufferStorageArea, |
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StaticStreamBuffer_t *pxStaticStreamBuffer ); |
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</pre> |
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* Creates a new stream buffer using statically allocated memory. See |
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* xStreamBufferCreate() for a version that uses dynamically allocated memory. |
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* |
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* configSUPPORT_STATIC_ALLOCATION must be set to 1 in FreeRTOSConfig.h for |
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* xStreamBufferCreateStatic() to be available. |
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* |
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* @param xBufferSizeBytes The size, in bytes, of the buffer pointed to by the |
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* pucStreamBufferStorageArea parameter. |
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* |
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* @param xTriggerLevelBytes The number of bytes that must be in the stream |
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* buffer before a task that is blocked on the stream buffer to wait for data is |
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* moved out of the blocked state. For example, if a task is blocked on a read |
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* of an empty stream buffer that has a trigger level of 1 then the task will be |
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* unblocked when a single byte is written to the buffer or the task's block |
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* time expires. As another example, if a task is blocked on a read of an empty |
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* stream buffer that has a trigger level of 10 then the task will not be |
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* unblocked until the stream buffer contains at least 10 bytes or the task's |
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* block time expires. If a reading task's block time expires before the |
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* trigger level is reached then the task will still receive however many bytes |
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* are actually available. Setting a trigger level of 0 will result in a |
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* trigger level of 1 being used. It is not valid to specify a trigger level |
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* that is greater than the buffer size. |
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* |
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* @param pucStreamBufferStorageArea Must point to a uint8_t array that is at |
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* least xBufferSizeBytes + 1 big. This is the array to which streams are |
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* copied when they are written to the stream buffer. |
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* |
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* @param pxStaticStreamBuffer Must point to a variable of type |
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* StaticStreamBuffer_t, which will be used to hold the stream buffer's data |
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* structure. |
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* |
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* @return If the stream buffer is created successfully then a handle to the |
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* created stream buffer is returned. If either pucStreamBufferStorageArea or |
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* pxStaticstreamBuffer are NULL then NULL is returned. |
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* |
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* Example use: |
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<pre> |
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// Used to dimension the array used to hold the streams. The available space |
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// will actually be one less than this, so 999. |
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#define STORAGE_SIZE_BYTES 1000 |
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|
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// Defines the memory that will actually hold the streams within the stream |
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// buffer. |
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static uint8_t ucStorageBuffer[ STORAGE_SIZE_BYTES ]; |
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|
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// The variable used to hold the stream buffer structure. |
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StaticStreamBuffer_t xStreamBufferStruct; |
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void MyFunction( void ) |
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{ |
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StreamBufferHandle_t xStreamBuffer; |
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const size_t xTriggerLevel = 1; |
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xStreamBuffer = xStreamBufferCreateStatic( sizeof( ucBufferStorage ), |
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xTriggerLevel, |
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ucBufferStorage, |
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&xStreamBufferStruct ); |
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// As neither the pucStreamBufferStorageArea or pxStaticStreamBuffer |
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// parameters were NULL, xStreamBuffer will not be NULL, and can be used to |
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// reference the created stream buffer in other stream buffer API calls. |
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|
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// Other code that uses the stream buffer can go here. |
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} |
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</pre> |
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* \defgroup xStreamBufferCreateStatic xStreamBufferCreateStatic |
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* \ingroup StreamBufferManagement |
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*/ |
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#define xStreamBufferCreateStatic( xBufferSizeBytes, xTriggerLevelBytes, pucStreamBufferStorageArea, pxStaticStreamBuffer ) xStreamBufferGenericCreateStatic( xBufferSizeBytes, xTriggerLevelBytes, pdFALSE, pucStreamBufferStorageArea, pxStaticStreamBuffer ) |
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|
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/** |
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* stream_buffer.h |
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* |
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<pre> |
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size_t xStreamBufferSend( StreamBufferHandle_t xStreamBuffer, |
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const void *pvTxData, |
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size_t xDataLengthBytes, |
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TickType_t xTicksToWait ); |
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</pre> |
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* |
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* Sends bytes to a stream buffer. The bytes are copied into the stream buffer. |
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* |
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* ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer |
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* implementation (so also the message buffer implementation, as message buffers |
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* are built on top of stream buffers) assumes there is only one task or |
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* 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 |
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* 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 |
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* block time to 0. Likewise, if there are to be multiple different readers |
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* then the application writer must place each call to a reading API function |
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* (such as xStreamBufferReceive()) inside a critical section and set the receive |
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* block time to 0. |
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* |
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* Use xStreamBufferSend() to write to a stream buffer from a task. Use |
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* xStreamBufferSendFromISR() to write to a stream buffer from an interrupt |
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* service routine (ISR). |
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* |
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* @param xStreamBuffer The handle of the stream buffer to which a stream is |
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* being sent. |
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* |
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* @param pvTxData A pointer to the buffer that holds the bytes to be copied |
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* into the stream buffer. |
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* |
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* @param xDataLengthBytes The maximum number of bytes to copy from pvTxData |
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* into the stream buffer. |
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* |
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* @param xTicksToWait The maximum amount of time the task should remain in the |
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* Blocked state to wait for enough space to become available in the stream |
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* buffer, should the stream buffer contain too little space to hold the |
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* another xDataLengthBytes bytes. The block time is specified in tick periods, |
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* so the absolute time it represents is dependent on the tick frequency. The |
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* macro pdMS_TO_TICKS() can be used to convert a time specified in milliseconds |
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* into a time specified in ticks. Setting xTicksToWait to portMAX_DELAY will |
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* cause the task to wait indefinitely (without timing out), provided |
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* INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. If a task times out |
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* before it can write all xDataLengthBytes into the buffer it will still write |
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* as many bytes as possible. A task does not use any CPU time when it is in |
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* the blocked state. |
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* |
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* @return The number of bytes written to the stream buffer. If a task times |
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* out before it can write all xDataLengthBytes into the buffer it will still |
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* write as many bytes as possible. |
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* |
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* Example use: |
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<pre> |
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void vAFunction( StreamBufferHandle_t xStreamBuffer ) |
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{ |
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size_t xBytesSent; |
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uint8_t ucArrayToSend[] = { 0, 1, 2, 3 }; |
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char *pcStringToSend = "String to send"; |
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const TickType_t x100ms = pdMS_TO_TICKS( 100 ); |
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|
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// Send an array to the stream buffer, blocking for a maximum of 100ms to |
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// wait for enough space to be available in the stream buffer. |
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xBytesSent = xStreamBufferSend( xStreamBuffer, ( void * ) ucArrayToSend, sizeof( ucArrayToSend ), x100ms ); |
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if( xBytesSent != sizeof( ucArrayToSend ) ) |
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{ |
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// The call to xStreamBufferSend() times out before there was enough |
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// space in the buffer for the data to be written, but it did |
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// successfully write xBytesSent bytes. |
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} |
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|
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// Send the string to the stream buffer. Return immediately if there is not |
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// enough space in the buffer. |
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xBytesSent = xStreamBufferSend( xStreamBuffer, ( void * ) pcStringToSend, strlen( pcStringToSend ), 0 ); |
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if( xBytesSent != strlen( pcStringToSend ) ) |
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{ |
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// The entire string could not be added to the stream buffer because |
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// there was not enough free space in the buffer, but xBytesSent bytes |
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// were sent. Could try again to send the remaining bytes. |
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} |
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} |
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</pre> |
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* \defgroup xStreamBufferSend xStreamBufferSend |
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* \ingroup StreamBufferManagement |
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*/ |
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size_t xStreamBufferSend( StreamBufferHandle_t xStreamBuffer, |
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const void *pvTxData, |
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size_t xDataLengthBytes, |
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TickType_t xTicksToWait ) PRIVILEGED_FUNCTION; |
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|
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/** |
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* stream_buffer.h |
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* |
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<pre> |
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size_t xStreamBufferSendFromISR( StreamBufferHandle_t xStreamBuffer, |
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const void *pvTxData, |
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size_t xDataLengthBytes, |
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BaseType_t *pxHigherPriorityTaskWoken ); |
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</pre> |
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* |
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* Interrupt safe version of the API function that sends a stream of bytes to |
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* the stream buffer. |
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* |
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* ***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 |
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* 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 |
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* block time to 0. |
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* |
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* Use xStreamBufferSend() to write to a stream buffer from a task. Use |
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* xStreamBufferSendFromISR() to write to a stream buffer from an interrupt |
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* service routine (ISR). |
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* |
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* @param xStreamBuffer The handle of the stream buffer to which a stream is |
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* being sent. |
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* |
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* @param pvTxData A pointer to the data that is to be copied into the stream |
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* buffer. |
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* |
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* @param xDataLengthBytes The maximum number of bytes to copy from pvTxData |
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* into the stream buffer. |
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* |
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* @param pxHigherPriorityTaskWoken It is possible that a stream buffer will |
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* have a task blocked on it waiting for data. Calling |
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* xStreamBufferSendFromISR() can make data available, and so cause a task that |
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* was waiting for data to leave the Blocked state. If calling |
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* xStreamBufferSendFromISR() causes a task to leave the Blocked state, and the |
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* unblocked task has a priority higher than the currently executing task (the |
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* task that was interrupted), then, internally, xStreamBufferSendFromISR() |
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* will set *pxHigherPriorityTaskWoken to pdTRUE. If |
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* xStreamBufferSendFromISR() sets this value to pdTRUE, then normally a |
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* context switch should be performed before the interrupt is exited. This will |
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* ensure that the interrupt returns directly to the highest priority Ready |
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* state task. *pxHigherPriorityTaskWoken should be set to pdFALSE before it |
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* is passed into the function. See the example code below for an example. |
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* |
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* @return The number of bytes actually written to the stream buffer, which will |
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* be less than xDataLengthBytes if the stream buffer didn't have enough free |
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* space for all the bytes to be written. |
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* |
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* Example use: |
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<pre> |
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// A stream buffer that has already been created. |
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StreamBufferHandle_t xStreamBuffer; |
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|
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void vAnInterruptServiceRoutine( void ) |
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{ |
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size_t xBytesSent; |
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char *pcStringToSend = "String to send"; |
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BaseType_t xHigherPriorityTaskWoken = pdFALSE; // Initialised to pdFALSE. |
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|
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// Attempt to send the string to the stream buffer. |
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xBytesSent = xStreamBufferSendFromISR( xStreamBuffer, |
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( void * ) pcStringToSend, |
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strlen( pcStringToSend ), |
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&xHigherPriorityTaskWoken ); |
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|
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if( xBytesSent != strlen( pcStringToSend ) ) |
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{ |
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// There was not enough free space in the stream buffer for the entire |
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// string to be written, ut xBytesSent bytes were written. |
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} |
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|
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// If xHigherPriorityTaskWoken was set to pdTRUE inside |
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// xStreamBufferSendFromISR() then a task that has a priority above the |
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// priority of the currently executing task was unblocked and a context |
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// switch should be performed to ensure the ISR returns to the unblocked |
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// task. In most FreeRTOS ports this is done by simply passing |
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// xHigherPriorityTaskWoken into taskYIELD_FROM_ISR(), which will test the |
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// variables value, and perform the context switch if necessary. Check the |
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// documentation for the port in use for port specific instructions. |
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taskYIELD_FROM_ISR( xHigherPriorityTaskWoken ); |
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} |
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</pre> |
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* \defgroup xStreamBufferSendFromISR xStreamBufferSendFromISR |
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* \ingroup StreamBufferManagement |
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*/ |
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size_t xStreamBufferSendFromISR( StreamBufferHandle_t xStreamBuffer, |
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const void *pvTxData, |
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size_t xDataLengthBytes, |
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BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION; |
|
|
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/** |
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* stream_buffer.h |
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* |
|
<pre> |
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size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer, |
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void *pvRxData, |
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size_t xBufferLengthBytes, |
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TickType_t xTicksToWait ); |
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</pre> |
|
* |
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* 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 |
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* be received. |
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* |
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* @param pvRxData A pointer to the buffer into which the received bytes will be |
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* copied. |
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* |
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* @param xBufferLengthBytes The length of the buffer pointed to by the |
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* 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 |
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* maximum set by xBufferLengthBytes. |
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* |
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* @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; |
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const TickType_t xBlockTime = pdMS_TO_TICKS( 20 ); |
|
|
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// Receive up to another sizeof( ucRxData ) bytes from the stream buffer. |
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// Wait in the Blocked state (so not using any CPU processing time) for a |
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// maximum of 100ms for the full sizeof( ucRxData ) number of bytes to be |
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// available. |
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xReceivedBytes = xStreamBufferReceive( xStreamBuffer, |
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( void * ) ucRxData, |
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sizeof( ucRxData ), |
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xBlockTime ); |
|
|
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if( xReceivedBytes > 0 ) |
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{ |
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// 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 ) */
|
|
|