diff --git a/integration-tests/src/test/scala/chiselTests/util/experimental/algorithm/Bitwise.scala b/integration-tests/src/test/scala/chiselTests/util/experimental/algorithm/Bitwise.scala new file mode 100644 index 00000000000..6c8eb4b45c5 --- /dev/null +++ b/integration-tests/src/test/scala/chiselTests/util/experimental/algorithm/Bitwise.scala @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: Apache-2.0 + +import chisel3._ +import chisel3.util._ +import chiseltest._ +import chiseltest.formal._ +import org.scalatest.flatspec.AnyFlatSpec +import scala.math.min + +class ScanLeftOrTestModule(width: Int) extends Module { + val input = IO(Input(UInt(width.W))) + + var lsb = false.B + val vec = for(b <- input.asBools) yield { + val cur = b || lsb + lsb = cur + cur + } + val ref = VecInit(vec).asUInt + + val testee = scanLeftOr(input) + + assert(testee === ref) +} + +class ScanRightOrTestModule(width: Int) extends Module { + val input = IO(Input(UInt(width.W))) + + val ref = Reverse(scanLeftOr(Reverse(input))) + val testee = scanRightOr(input) + + assert(testee === ref) +} + +class scanOrTest extends AnyFlatSpec with ChiselScalatestTester with Formal { + "scanLeftOr" should "compute correctly" in { + for(i <- 1 to 16) { + verify(new ScanLeftOrTestModule(i), Seq(BoundedCheck(1))) + } + } + + "scanRightOr" should "compute correctly" in { + for(i <- 1 to 16) { + verify(new ScanRightOrTestModule(i), Seq(BoundedCheck(1))) + } + } +} diff --git a/src/main/scala/chisel3/experimental/util/algorithm/Bitwise.scala b/src/main/scala/chisel3/experimental/util/algorithm/Bitwise.scala new file mode 100644 index 00000000000..6b4bb8f0307 --- /dev/null +++ b/src/main/scala/chisel3/experimental/util/algorithm/Bitwise.scala @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: Apache-2.0 + +package chisel3.util + +import chisel3._ + +/** Map each bit to the logical OR of itself and all bits with lower index + * + * Here `scanLeft` means "start from the left and iterate to the right, where left is the lowest index", a common operation on arrays and lists. + * @example {{{ + * scanLeftOr("b00001000".U(8.W)) // Returns "b11111000".U + * scanLeftOr("b00010100".U(8.W)) // Returns "b11111100".U + * scanLeftOr("b00000000".U(8.W)) // Returns "b00000000".U + * }}} + */ +object scanLeftOr { + def apply(data: UInt): UInt = { + val width = data.widthOption match { + case Some(w) => w + case None => throw new IllegalArgumentException("Cannot call scanLeftOr on data with unknown width.") + } + + def helper(s: Int, x: UInt): UInt = + if (s >= width) x else helper(s + s, x | (x << s)(width - 1, 0)) + helper(1, data)(width - 1, 0) + } +} + +/** Map each bit to the logical OR of itself and all bits with higher index + * + * Here `scanRight` means "start from the right and iterate to the left, where right is the highest index", a common operation on arrays and lists. + * @example {{{ + * scanRightOr("b00001000".U) // Returns "b00001111".U + * scanRightOr("b00010100".U) // Returns "b00011111".U + * scanRightOr("b00000000".U) // Returns "b00000000".U + * }}} + */ +object scanRightOr { + def apply(data: UInt): UInt = { + val width = data.widthOption match { + case Some(w) => w + case None => throw new IllegalArgumentException("Cannot call scanRightOr on data with unknown width.") + } + def helper(s: Int, x: UInt): UInt = + if (s >= width) x else helper(s + s, x | (x >> s)) + helper(1, data)(width - 1, 0) + } +}