ringbuf: Fix case where xTaskGetTickCount() overflows but task timeout point doesn't
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@ -471,7 +471,8 @@ BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t dataSize,
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ringbuf_t *rb=(ringbuf_t *)ringbuf;
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size_t needed_size=dataSize+sizeof(buf_entry_hdr_t);
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BaseType_t done=pdFALSE;
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portTickType ticks_end=xTaskGetTickCount() + ticks_to_wait;
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TickType_t ticks_end = xTaskGetTickCount() + ticks_to_wait;
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TickType_t ticks_remaining = ticks_to_wait;
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configASSERT(rb);
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@ -486,16 +487,25 @@ BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t dataSize,
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if (ringbufferFreeMem(rb) < needed_size) {
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//Data does not fit yet. Wait until the free_space_sem is given, then re-evaluate.
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BaseType_t r = xSemaphoreTake(rb->free_space_sem, ticks_to_wait);
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BaseType_t r = xSemaphoreTake(rb->free_space_sem, ticks_remaining);
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if (r == pdFALSE) {
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//Timeout.
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return pdFALSE;
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}
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//Adjust ticks_to_wait; we may have waited less than that and in the case the free memory still is not enough,
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//Adjust ticks_remaining; we may have waited less than that and in the case the free memory still is not enough,
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//we will need to wait some more.
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ticks_to_wait = ticks_end - xTaskGetTickCount();
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if (ticks_to_wait != portMAX_DELAY) {
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ticks_remaining = ticks_end - xTaskGetTickCount();
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}
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} while (ringbufferFreeMem(rb) < needed_size && ticks_end >= xTaskGetTickCount());
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// ticks_remaining will always be less than or equal to the original ticks_to_wait,
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// unless the timeout is reached - in which case it unsigned underflows to a much
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// higher value.
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//
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// (Check is written this non-intuitive way to allow for the case where xTaskGetTickCount()
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// has overflowed but the ticks_end value has not overflowed.)
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}
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} while (ringbufferFreeMem(rb) < needed_size && ticks_remaining > 0 && ticks_remaining <= ticks_to_wait);
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//Lock the mux in order to make sure no one else is messing with the ringbuffer and do the copy.
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portENTER_CRITICAL(&rb->mux);
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