Note 12 - Equity Incentive Plans and Employee Benefits (Tables)

12 Months Ended

Jan. 28, 2017

Notes Tables

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Number of Options Outstanding			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
As of February 1, 2014		4,094,621		$	11.24		4.8
Granted (Weighted average fair value of $1.80)		467,400			4.54
Cancelled		(734,702	)		9.52
Exercised		(59,261	)		4.59
As of January 31, 2015		3,768,058			10.86		4.9
Granted (Weighted average fair value of $3.64)		104,200			8.74
Cancelled		(415,146	)		10.39
Exercised		(523,441	)		6.83
As of January 30, 2016		2,933,671			11.57		4.2
Granted (Weighted average fair value of $3.14)		483,400			6.87
Cancelled		(556,616	)		11.41
Exercised		(194,884	)		4.75
As of January 28, 2017		2,665,571		$	11.25		4.5	$	566,742
Ending vested and expected to vest		2,621,451		$	11.33		4.4	$	565,667
Ending exercisable		2,131,470		$	12.35		3.3	$	513,643

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

Options Outstanding and Exercisable
Range of Exercise Prices			Number Outstanding		Weighted Average Remaining Contractual Term (Years)		Weighted Average Exercise Price Per Share		Number Exercisable		Weighted Average Exercise Price Per Share
$0.92	-	$4.98		297,053		6.95	$	4.60		260,579	$	4.55
$5.76	-	$6.48		335,539		8.34		6.36		95,155		6.08
$6.49	-	$7.30		294,240		7.56		6.80		171,982		6.60
$7.44	-	$10.51		209,083		7.29		8.39		74,098		9.28
$10.59	-	$10.59		318,700		2.97		10.59		318,700		10.59
$10.87	-	$10.87		300,600		1.74		10.87		300,600		10.87
$11.07	-	$11.09		353,934		2.39		11.08		353,934		11.08
$11.47	-	$15.25		348,422		2.15		13.23		348,422		13.23
$15.64	-	$41.58		164,000		1.29		33.83		164,000		33.83
$45.83	-	$45.83		44,000		0.77		45.83		44,000		45.83
				2,665,571		4.48	$	11.25		2,131,470	$	12.35

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Restricted Stock Units			Weighted Average Grant Date Fair Value per Unit		Aggregate Intrinsic Value
As of February 1, 2014		468,507		$	5.78		2,197,298
Granted		1,157,127			4.91
Vested		(257,315	)		6.22
Cancelled/forfeited		(54,404	)		6.09
As of January 31, 2015		1,313,915			4.91		8,356,499
Granted		1,165,832			8.74
Vested		(861,259	)		5.52
Cancelled/forfeited		(215,876	)		7.37
As of January 30, 2016		1,402,612			7.53		9,299,318
Granted		1,057,944			7.42
Vested		(783,909	)		7.13
Cancelled/forfeited		(38,029	)		7.67
As of January 28, 2017		1,638,618		$	7.64	$	10,487,155

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Fiscal Years Ended
Stock options	January 28, 2017			January 30, 2016			January 31, 2015
Expected volatility		50.77	%		44.84	%		42.72	%
Risk-free interest rate		1.27	%		1.60	%		1.63	%
Expected term (in years)		5.23			5.19			5.11
Dividend yield		0	%		0	%		0	%
Weighted average fair value at grant date	$	3.14		$	3.64		$	1.80

	Fiscal Years Ended
Employee stock purchase plan	January 28, 2017			January 30, 2016			January 31, 2015
Expected volatility		57.19	%		77.90	%		50.05	%
Risk-free interest rate		0.50	%		0.44	%		0.08	%
Expected term (in years)		0.50			0.46			0.50
Dividend yield		0	%		0	%		0	%
Weighted average fair value at grant date	$	1.91		$	2.24		$	1.67

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Fiscal Years Ended
	January 28, 2017		January 30, 2016		January 31, 2015
Cost of revenue	$	294	$	227	$	190
Research and development		3,452		3,241		3,147
Sales and marketing		1,197		1,151		979
General and administrative		1,562		1,940		1,963
Total stock-based compensation	$	6,505	$	6,559	$	6,279

Schedule of Shares Reserved For Future Issuance [Table Text Block]

	Shares Reserved
Authorized for future grants under stock incentive plans		4,836,384
Stock options outstanding		2,665,571
Restricted stock units outstanding		1,638,618
Shares reserved for future issuance		9,140,573