Function otLinkGetTxDirectRetrySuccessHistogram 

pub unsafe extern "C" fn otLinkGetTxDirectRetrySuccessHistogram(
    aInstance: *mut otInstance,
    aSize: *mut u16,
) -> *const u32

Gets histogram of retries for a single direct packet until success.

Requires OPENTHREAD_CONFIG_MAC_RETRY_SUCCESS_HISTOGRAM_ENABLE.

The configuration OPENTHREAD_CONFIG_MAC_RETRY_SUCCESS_HISTOGRAM_MAX_SIZE_COUNT_DIRECT specifies the size of the direct TX histogram array.

@param[in] aInstance A pointer to an OpenThread instance. @param[out] aSize A pointer to where the size of returned histogram array is placed.

@returns A pointer to the histogram of retries (in a form of an array). The n-th element indicates that the packet has been sent with n-th retry. If the number of retries is larger than the histogram array max size, the last entry counts all retries at or above the limit.