diff options
Diffstat (limited to 'src/main')
| -rw-r--r-- | src/main/scala/chisel3/util/Math.scala | 36 |
1 files changed, 34 insertions, 2 deletions
diff --git a/src/main/scala/chisel3/util/Math.scala b/src/main/scala/chisel3/util/Math.scala index f9278c7d..105b4161 100644 --- a/src/main/scala/chisel3/util/Math.scala +++ b/src/main/scala/chisel3/util/Math.scala @@ -5,8 +5,7 @@ package chisel3.util -import chisel3._ -import chisel3.internal.chiselRuntimeDeprecated +import chisel3.internal /** Compute the log2 of a Scala integer, rounded up, with min value of 1. * Useful for getting the number of bits needed to represent some number of states (in - 1), @@ -99,3 +98,36 @@ object isPow2 { def apply(in: BigInt): Boolean = in > 0 && ((in & (in-1)) == 0) def apply(in: Int): Boolean = apply(BigInt(in)) } + + +object unsignedBitLength { + /** Return the number of bits required to encode a specific value, assuming no sign bit is required. + * + * Basically, `n.bitLength`. NOTE: This will return 0 for a value of 0. + * This reflects the Chisel assumption that a zero width wire has a value of 0. + * @param in - the number to be encoded. + * @return - an Int representing the number of bits to encode. + */ + def apply(in: BigInt): Int = { + require(in >= 0) + in.bitLength + } +} + +object signedBitLength { + /** Return the number of bits required to encode a specific value, assuming a sign bit is required. + * + * Basically, 0 for 0, 1 for -1, and `n.bitLength` + 1 for everything else. + * This reflects the Chisel assumption that a zero width wire has a value of 0. + * @param in - the number to be encoded. + * @return - an Int representing the number of bits to encode. + */ + def apply(in: BigInt): Int = { + in.toInt match { + case 0 => 0 + case -1 => 1 + case _ => in.bitLength + 1 + } + + } +} |
