Second Largest

Prompt

Given a clocked sequence of unsigned values, output the second-largest value seen so far in the sequence. If only one value is seen, then the output (dout) should equal 0. Note that the values are treated as separate candidates for being the second largest value.

When the reset-low signal (resetn) goes low, all previous values seen in the input sequence should no longer be considered for thee calculation of the second largest value, and the output dout should restart from 0 on the next cycle.

Input & Output Signals

• clk: Clock signal.
• resetn: Synchronous reset-low signal.
• din: Input data sequence.
• dout: Second-largest value seen so far.

Output signals during reset

• dout: 0 when resetn is active.

Example

• Data width: 32
• Clock cycle 1
  • resetn: h0
  • din: h2
• Clock cycle 2
  • resetn: h1
  • din: h2
• Clock cycle 3
  • resetn: h1
  • din: h6
• Clock cycle 4
  • resetn: h1
  • din: h0
• Clock cycle 5
  • resetn: h1
  • din: he
• Clock cycle 6
  • resetn: h1
  • din: hc
• Clock cycle 7
  • resetn: h0
  • din: h0
• Clock cycle 8
  • resetn: h1
  • din: h1
• Clock cycle 9
  • resetn: h1
  • din: h2