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// SPDX-License-Identifier: Apache-2.0
package chisel3.util.experimental.decode
import chisel3._
import chisel3.experimental.{annotate, ChiselAnnotation}
import chisel3.util.{pla, BitPat}
import chisel3.util.experimental.{getAnnotations, BitSet}
import chisel3.internal.Builder
import firrtl.annotations.Annotation
import logger.LazyLogging
object decoder extends LazyLogging {
/** Use a specific [[Minimizer]] to generated decoded signals.
*
* @param minimizer specific [[Minimizer]], can be [[QMCMinimizer]] or [[EspressoMinimizer]].
* @param input input signal that contains decode table input
* @param truthTable [[TruthTable]] to decode user input.
* @return decode table output.
*/
def apply(minimizer: Minimizer, input: UInt, truthTable: TruthTable): UInt = {
val minimizedTable = getAnnotations().collect {
case DecodeTableAnnotation(_, in, out) => TruthTable.fromString(in) -> TruthTable.fromString(out)
}.toMap.getOrElse(truthTable, minimizer.minimize(truthTable))
if (minimizedTable.table.isEmpty) {
val outputs = Wire(UInt(minimizedTable.default.getWidth.W))
outputs := minimizedTable.default.value.U(minimizedTable.default.getWidth.W)
outputs
} else {
val (plaInput, plaOutput) =
pla(minimizedTable.table.toSeq, BitPat(minimizedTable.default.value.U(minimizedTable.default.getWidth.W)))
assert(plaOutput.isSynthesizable, s"Using DecodeTableAnnotation on non-hardware value $plaOutput")
annotate(new ChiselAnnotation {
override def toFirrtl: Annotation =
DecodeTableAnnotation(plaOutput.toTarget, truthTable.toString, minimizedTable.toString)
})
plaInput := input
plaOutput
}
}
/** Use [[EspressoMinimizer]] to generated decoded signals.
*
* @param input input signal that contains decode table input
* @param truthTable [[TruthTable]] to decode user input.
* @return decode table output.
*/
def espresso(input: UInt, truthTable: TruthTable): UInt = apply(EspressoMinimizer, input, truthTable)
/** Use [[QMCMinimizer]] to generated decoded signals.
*
* @param input input signal that contains decode table input
* @param truthTable [[TruthTable]] to decode user input.
* @return decode table output.
*/
def qmc(input: UInt, truthTable: TruthTable): UInt = apply(QMCMinimizer, input, truthTable)
/** try to use [[EspressoMinimizer]] to decode `input` by `truthTable`
* if `espresso` not exist in your PATH environment it will fall back to [[QMCMinimizer]], and print a warning.
*
* @param input input signal that contains decode table input
* @param truthTable [[TruthTable]] to decode user input.
* @return decode table output.
*/
def apply(input: UInt, truthTable: TruthTable): UInt = {
def qmcFallBack(input: UInt, truthTable: TruthTable) = {
"""fall back to QMC.
|Quine-McCluskey is a NP complete algorithm, may run forever or run out of memory in large decode tables.
|To get rid of this warning, please use `decoder.qmc` directly, or add espresso to your PATH.
|""".stripMargin
qmc(input, truthTable)
}
try espresso(input, truthTable)
catch {
case EspressoNotFoundException =>
logger.error(s"espresso is not found in your PATH:\n${sys.env("PATH").split(":").mkString("\n")}".stripMargin)
qmcFallBack(input, truthTable)
case e: java.io.IOException =>
logger.error(s"espresso failed to run with ${e.getMessage}")
qmcFallBack(input, truthTable)
}
}
/** Generate a decoder circuit that matches the input to each bitSet.
*
* The resulting circuit functions like the following but is optimized with a logic minifier.
* {{{
* when(input === bitSets(0)) { output := b000001 }
* .elsewhen (input === bitSets(1)) { output := b000010 }
* ....
* .otherwise { if (errorBit) output := b100000 else output := DontCare }
* }}}
*
* @param input input to the decoder circuit, width should be equal to bitSets.width
* @param bitSets set of ports to be matched, all width should be the equal
* @param errorBit whether generate an additional decode error bit at MSB of output.
* @return decoded wire
*/
def bitset(input: chisel3.UInt, bitSets: Seq[BitSet], errorBit: Boolean = false): chisel3.UInt =
chisel3.util.experimental.decode.decoder(
input,
chisel3.util.experimental.decode.TruthTable.fromString(
{
bitSets.zipWithIndex.flatMap {
case (bs, i) =>
bs.terms.map(bp =>
s"${bp.rawString}->${if (errorBit) "0" else ""}${"0" * (bitSets.size - i - 1)}1${"0" * i}"
)
} ++ Seq(s"${if (errorBit) "1" ++ "0" * bitSets.size else "?" * bitSets.size}")
}.mkString("\n")
)
)
}
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