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// See LICENSE for license details.
package cookbook
import chisel3._
import chisel3.util._
/* ### How do I create a finite state machine?
*
* Use Chisel Enum to construct the states and switch & is to construct the FSM
* control logic
*/
class DetectTwoOnes extends Module {
val io = IO(new Bundle {
val in = Input(Bool())
val out = Output(Bool())
})
val sNone :: sOne1 :: sTwo1s :: Nil = Enum(3)
val state = RegInit(sNone)
io.out := (state === sTwo1s)
switch (state) {
is (sNone) {
when (io.in) {
state := sOne1
}
}
is (sOne1) {
when (io.in) {
state := sTwo1s
} .otherwise {
state := sNone
}
}
is (sTwo1s) {
when (!io.in) {
state := sNone
}
}
}
}
class DetectTwoOnesTester extends CookbookTester(10) {
val dut = Module(new DetectTwoOnes)
// Inputs and expected results
val inputs: Vec[Bool] = Vec(false.B, true.B, false.B, true.B, true.B, true.B, false.B, true.B, true.B, false.B)
val expected: Vec[Bool] = Vec(false.B, false.B, false.B, false.B, false.B, true.B, true.B, false.B, false.B, true.B)
dut.io.in := inputs(cycle)
assert(dut.io.out === expected(cycle))
}
class FSMSpec extends CookbookSpec {
"DetectTwoOnes" should "work" in {
assertTesterPasses { new DetectTwoOnesTester }
}
}
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