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stream_buffer.h
BaseType_t xStreamBufferSetTriggerLevel( StreamBufferHandle_t xStreamBuffer,
size_t xTriggerLevel );
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().
Stream buffer functionality is enabled by including the FreeRTOS/source/stream_buffer.c
source file in the build.
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Parameters:
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xStreamBuffer
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The handle of the stream buffer being updated.
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xTriggerLevel
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The new trigger level for the stream buffer.
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Returns:
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If xTriggerLevel was less than or equal to the steam buffer's length then
the trigger level will be updated and pdTRUE is returned. Otherwise pdFALSE
is returned.
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