Histogram.cols: def of bend-parallel@0.1.0.0
Import: import bend-parallel@0.1.0.0/histogram.bend as Histogram
Lines 268-284 of bend-parallel@0.1.0.0/histogram.bend: https://jend.leeeet.dev/read.txt?path=bend-parallel@0.1.0.0/histogram.bend&start_line=268&end_line=284

import Base

# Pass 2b's forks: d levels down to groups of 2^w columns under group index
# j. ft and fc are two handles each to the table and the counts. Group j
# reads only its columns of the table and writes only its counts (entries
# j * 2^w to j * 2^w + 2^w - 1): no two lanes write one slot.
def cols(+d: Nat, +j: U32, +w: Nat, +k: U32, +o: U32, +step: U32, +nb: Nat, ft: Array<U32> & Array<U32>, fc: Array<U32> & Array<U32>) -> Two:
  match d:
    case 0n:
      (t, t2) = ft
      (cs, cs2) = fc
      two.rejoin(t2, cs2, cols.go(U32.to_nat((U32.shln(1, w) - 1 : U32)), U32.shln(j, w), k, o, step, nb, Two{t, cs}))
    case 1n+p:
      (t0, t1) = ft
      (c0, c1) = fc
      +i = (j * 2 : U32)
      l r = cols(p, i, w, k, o, step, nb, Array.fork(U32, t0), Array.fork(U32, c0))
        cols(p, (i + 1 : U32), w, k, o, step, nb, Array.fork(U32, t1), Array.fork(U32, c1))
      two.join(l, r)

Uses (15):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Array
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Array.fork
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.mul
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.shln
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.sub
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.to_nat
  https://jend.leeeet.dev/definition.txt?path=bend-parallel@0.1.0.0/histogram.bend&name=Two
  https://jend.leeeet.dev/definition.txt?path=bend-parallel@0.1.0.0/histogram.bend&name=cols.go
  https://jend.leeeet.dev/definition.txt?path=bend-parallel@0.1.0.0/histogram.bend&name=two.join
  https://jend.leeeet.dev/definition.txt?path=bend-parallel@0.1.0.0/histogram.bend&name=two.rejoin