def get_block_cell_value

bend-edit-distance@0.2.2.0 · src/Myers.bend:133

import Base

133# getBlockCellValues(block)[W], without constructing the other 31 cells.
134# Walking up a row subtracts its positive vertical difference and adds its
135# negative difference. W is always in 0..31, never a whole extra block.
136def get_block_cell_value(padding: Nat, +pv: U32, +mv: U32, score: U32) -> U32:
137  match padding:
138    case 0n:
139      score
140    case 1n+p:
141      get_block_cell_value(p, U32.shl(pv), U32.shl(mv),
142        U32.add(U32.sub(score, U32.shrn(pv, 31n)), U32.shrn(mv, 31n)))