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// See LICENSE for license details.
package chisel3.util
import chisel3._
/** A counter module
* @param n number of counts before the counter resets (or one more than the
* maximum output value of the counter), need not be a power of two
*/
class Counter(val n: Int) {
require(n >= 0)
val value = if (n > 1) Reg(init=UInt(0, log2Up(n))) else UInt(0)
/** Increment the counter, returning whether the counter currently is at the
* maximum and will wrap. The incremented value is registered and will be
* visible on the next cycle.
*/
def inc(): Bool = {
if (n > 1) {
val wrap = value === UInt(n-1)
value := value + UInt(1)
if (!isPow2(n)) {
when (wrap) { value := UInt(0) }
}
wrap
} else {
Bool(true)
}
}
}
/** Counter Object
* Example Usage:
* {{{ val countOn = Bool(true) // increment counter every clock cycle
* val (myCounterValue, myCounterWrap) = Counter(countOn, n)
* when ( myCounterValue === UInt(3) ) { ... } }}}*/
object Counter
{
def apply(n: Int): Counter = new Counter(n)
def apply(cond: Bool, n: Int): (UInt, Bool) = {
val c = new Counter(n)
var wrap: Bool = null
when (cond) { wrap = c.inc() }
(c.value, cond && wrap)
}
}
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