ScalaDocs improvement for utils Math, MixedVec (#1019)

1 files changed, 58 insertions, 5 deletions

diff --git a/src/main/scala/chisel3/util/Math.scala b/src/main/scala/chisel3/util/Math.scala
index 0e1b36d5..f9278c7d 100644
--- a/src/main/scala/chisel3/util/Math.scala
+++ b/src/main/scala/chisel3/util/Math.scala
@@ -8,7 +8,21 @@ package chisel3.util
 import chisel3._
 import chisel3.internal.chiselRuntimeDeprecated
 
-/** Compute the log2 rounded up with min value of 1 */
+/** 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),
+  * To get the number of bits needed to represent some number n, use log2Up(n + 1).
+  * with the minimum value preventing the creation of currently-unsupported zero-width wires.
+  *
+  * Note: prefer to use log2Ceil when in is known to be > 1 (where log2Ceil(in) > 0).
+  * This will be deprecated when zero-width wires is supported.
+  *
+  * @example {{{
+  * log2Up(1)  // returns 1
+  * log2Up(2)  // returns 1
+  * log2Up(3)  // returns 2
+  * log2Up(4)  // returns 2
+  * }}}
+  */
 object log2Up {
   // Do not deprecate until zero-width wires fully work:
   // https://github.com/freechipsproject/chisel3/issues/847
@@ -17,7 +31,20 @@ object log2Up {
   def apply(in: BigInt): Int = Chisel.log2Up(in)
 }
 
-/** Compute the log2 rounded up */
+/** Compute the log2 of a Scala integer, rounded up.
+  * Useful for getting the number of bits needed to represent some number of states (in - 1).
+  * To get the number of bits needed to represent some number n, use log2Ceil(n + 1).
+  *
+  * Note: can return zero, and should not be used in cases where it may generate unsupported
+  * zero-width wires.
+  *
+  * @example {{{
+  * log2Ceil(1)  // returns 0
+  * log2Ceil(2)  // returns 1
+  * log2Ceil(3)  // returns 2
+  * log2Ceil(4)  // returns 2
+  * }}}
+  */
 object log2Ceil {
   def apply(in: BigInt): Int = {
     require(in > 0)
@@ -26,7 +53,15 @@ object log2Ceil {
   def apply(in: Int): Int = apply(BigInt(in))
 }
 
-/** Compute the log2 rounded down with min value of 1 */
+/** Compute the log2 of a Scala integer, rounded down, with min value of 1.
+  *
+  * @example {{{
+  * log2Down(1)  // returns 1
+  * log2Down(2)  // returns 1
+  * log2Down(3)  // returns 1
+  * log2Down(4)  // returns 2
+  * }}}
+  */
 object log2Down {
   // Do not deprecate until zero-width wires fully work:
   // https://github.com/freechipsproject/chisel3/issues/847
@@ -35,13 +70,31 @@ object log2Down {
   def apply(in: BigInt): Int = Chisel.log2Down(in)
 }
 
-/** Compute the log2 rounded down */
+/** Compute the log2 of a Scala integer, rounded down.
+  *
+  * Can be useful in computing the next-smallest power of two.
+  *
+  * @example {{{
+  * log2Floor(1)  // returns 0
+  * log2Floor(2)  // returns 1
+  * log2Floor(3)  // returns 1
+  * log2Floor(4)  // returns 2
+  * }}}
+  */
 object log2Floor {
   def apply(in: BigInt): Int = log2Ceil(in) - (if (isPow2(in)) 0 else 1)
   def apply(in: Int): Int = apply(BigInt(in))
 }
 
-/** Check if an Integer is a power of 2 */
+/** Returns whether a Scala integer is a power of two.
+  *
+  * @example {{{
+  * isPow2(1)  // returns true
+  * isPow2(2)  // returns true
+  * isPow2(3)  // returns false
+  * isPow2(4)  // returns true
+  * }}}
+  */
 object isPow2 {
   def apply(in: BigInt): Boolean = in > 0 && ((in & (in-1)) == 0)
   def apply(in: Int): Boolean = apply(BigInt(in))