Note 2 - Business Acquisitions - Unaudited Pro Forma Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 29, 2018	[1],[2]	Sep. 29, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 30, 2017	[1],[2]	Sep. 30, 2017	[1]	Jul. 01, 2017	[1]	Apr. 01, 2017	[1]	Dec. 29, 2018		Dec. 30, 2017	Dec. 31, 2016
Net sales	$ 170,637		$ 86,164	[2]	$ 99,817	[2]	$ 95,150	[2]	$ 84,090		$ 93,651		$ 93,866		$ 81,097		$ 451,768	[1],[2]	$ 352,704	$ 282,084
Net loss	$ (56,997)		$ 4,803		$ 11,648		$ 8,122		$ 6,895		$ 8,755		$ 10,430		$ 6,763		(32,424)		32,843	$ 3,039
Xcerra [Member]
Net sales, pro forma																	771,314		808,255
Net income (loss), pro forma																	$ 9,473		$ (29,545)

[1] All quarters presented above were comprised of 13 weeks, except for the first quarter ended March 25, 2017, and the third quarter ended September 30, 2017, which were comprised of 12 and 14 weeks, respectively.

[2] We acquired Xcerra on October 1, 2018. The results of Xcerra have been included in our results of operations from the date of acquisition. See Note 2, "Business Acquisitions" for additional information regarding this transaction. Total operating expenses in the fourth quarter of 2018 include charges related to the acquisition of Xcerra as follows - $37.8 million in restructuring charges comprised of $19.1 million of inventory end-of-manufacturing write-downs related to one of Xcerra's products, employee severance costs of $17.8 million and $0.9 million for other restructuring costs. We also recorded $13.1 million for the amortization of acquisition-related intangibles.