def adc

bend-lawful-stdlib@0.1.0.0 · src/float/bin.bend:77

import Base

77# a + b + carry, one bit at a time: bits 0+0 pass the carry through and
78# carry nothing, 0+1 flip it and carry it, 1+1 pass it and carry one
79def adc(a: Bin, b: Bin, +c: Bool) -> Bin:
80  match a b:
81    case BZ{} b:
82      adc.one(b, c)
83    case a BZ{}:
84      adc.one(a, c)
85    case B0{x} B0{y}:
86      cons(c, adc(x, y, False{}))
87    case B0{x} B1{y}:
88      cons(Bool.not(c), adc(x, y, c))
89    case B1{x} B0{y}:
90      cons(Bool.not(c), adc(x, y, c))
91    case B1{x} B1{y}:
92      cons(c, adc(x, y, True{}))