# SPDX-License-Identifier: GPL-2.0

humanize()
{
	local speed=$1; shift

	for unit in bps Kbps Mbps Gbps; do
		if (($(echo "$speed < 1024" | bc))); then
			break
		fi

		speed=$(echo "scale=1; $speed / 1024" | bc)
	done

	echo "$speed${unit}"
}

rate()
{
	local t0=$1; shift
	local t1=$1; shift
	local interval=$1; shift

	echo $((8 * (t1 - t0) / interval))
}

start_traffic()
{
	local h_in=$1; shift    # Where the traffic egresses the host
	local sip=$1; shift
	local dip=$1; shift
	local dmac=$1; shift

	$MZ $h_in -p 8000 -A $sip -B $dip -c 0 \
		-a own -b $dmac -t udp -q &
	sleep 1
}

stop_traffic()
{
	# Suppress noise from killing mausezahn.
	{ kill %% && wait %%; } 2>/dev/null
}

check_rate()
{
	local rate=$1; shift
	local min=$1; shift
	local what=$1; shift

	if ((rate > min)); then
		return 0
	fi

	echo "$what $(humanize $ir) < $(humanize $min)" > /dev/stderr
	return 1
}

measure_rate()
{
	local sw_in=$1; shift   # Where the traffic ingresses the switch
	local host_in=$1; shift # Where it ingresses another host
	local counter=$1; shift # Counter to use for measurement
	local what=$1; shift

	local interval=10
	local i
	local ret=0

	# Dips in performance might cause momentary ingress rate to drop below
	# 1Gbps. That wouldn't saturate egress and MC would thus get through,
	# seemingly winning bandwidth on account of UC. Demand at least 2Gbps
	# average ingress rate to somewhat mitigate this.
	local min_ingress=2147483648

	for i in {5..0}; do
		local t0=$(ethtool_stats_get $host_in $counter)
		local u0=$(ethtool_stats_get $sw_in $counter)
		sleep $interval
		local t1=$(ethtool_stats_get $host_in $counter)
		local u1=$(ethtool_stats_get $sw_in $counter)

		local ir=$(rate $u0 $u1 $interval)
		local er=$(rate $t0 $t1 $interval)

		if check_rate $ir $min_ingress "$what ingress rate"; then
			break
		fi

		# Fail the test if we can't get the throughput.
		if ((i == 0)); then
			ret=1
		fi
	done

	echo $ir $er
	return $ret
}