// ok to overwrite y in place
			y = y.trunc(y, n)
		} else {
			y = nat(nil).trunc(y, n)
		}
	}
	if x.cmp(y) >= 0 {
		return z.sub(x, y)
	}
	// x - y < 0; x - y mod 2ⁿ = x - y + 2ⁿ = 2ⁿ - (y - x) = 1 + 2ⁿ-1 - (y - x) = 1 + ^(y - x).
	z = z.sub(y, x)
	for uint(len(z))*_W < n {
		z = append(z, 0)
	}
	for i := range z {
		z[i] = ^z[i]
	}
	z = z.trunc(z, n)
	return z.add(z, natOne)

entirely for the purpose of simplifying the run-time analysis, rather than
simplifying the presentation. Instead of a single algorithm that loops over
quotient digits, the paper presents two mutually-recursive algorithms, for
2n-by-n and 3n-by-2n. The paper also does not present any general (n+m)-by-n
algorithm.

The proofs in the paper are remarkably complex, especially considering that

00000090  f7 0d 01 01 01 05 00 03  81 8d 00 30 81 89 02 81  |...........0....|
000000a0  81 00 ba 6f aa 86 bd cf  bf 9f f2 ef 5c 94 60 78  |...o........\.`x|
000000b0  6f e8 13 f2 d1 96 6f cd  d9 32 6e 22 37 ce 41 f9  |o.....o..2n"7.A.|
000000c0  ca 5d 29 ac e1 27 da 61  a2 ee 81 cb 10 c7 df 34  |.])..'.a.......4|
000000d0  58 95 86 e9 3d 19 e6 5c  27 73 60 c8 8d 78 02 f4  |X...=..\'s`..x..|

00000090  f7 0d 01 01 01 05 00 03  81 8d 00 30 81 89 02 81  |...........0....|
000000a0  81 00 ba 6f aa 86 bd cf  bf 9f f2 ef 5c 94 60 78  |...o........\.`x|
000000b0  6f e8 13 f2 d1 96 6f cd  d9 32 6e 22 37 ce 41 f9  |o.....o..2n"7.A.|
000000c0  ca 5d 29 ac e1 27 da 61  a2 ee 81 cb 10 c7 df 34  |.])..'.a.......4|
000000d0  58 95 86 e9 3d 19 e6 5c  27 73 60 c8 8d 78 02 f4  |X...=..\'s`..x..|

//    grow as n log n but the algorithm is not stable.
//  - "Fast Stable In-Place Sorting with O(n) Data Moves" J.I. Munro and
//    V. Raman in Algorithmica (1996) 16, 115-160:
//    This algorithm either needs additional 2n bits or works only if there
//    are enough different elements available to encode some permutations
//    which have to be undone later (so not stable on any input).

00000090  f7 0d 01 01 01 05 00 03  81 8d 00 30 81 89 02 81  |...........0....|
000000a0  81 00 ba 6f aa 86 bd cf  bf 9f f2 ef 5c 94 60 78  |...o........\.`x|
000000b0  6f e8 13 f2 d1 96 6f cd  d9 32 6e 22 37 ce 41 f9  |o.....o..2n"7.A.|
000000c0  ca 5d 29 ac e1 27 da 61  a2 ee 81 cb 10 c7 df 34  |.])..'.a.......4|
000000d0  58 95 86 e9 3d 19 e6 5c  27 73 60 c8 8d 78 02 f4  |X...=..\'s`..x..|

00000090  f7 0d 01 01 01 05 00 03  81 8d 00 30 81 89 02 81  |...........0....|
000000a0  81 00 ba 6f aa 86 bd cf  bf 9f f2 ef 5c 94 60 78  |...o........\.`x|
000000b0  6f e8 13 f2 d1 96 6f cd  d9 32 6e 22 37 ce 41 f9  |o.....o..2n"7.A.|
000000c0  ca 5d 29 ac e1 27 da 61  a2 ee 81 cb 10 c7 df 34  |.])..'.a.......4|
000000d0  58 95 86 e9 3d 19 e6 5c  27 73 60 c8 8d 78 02 f4  |X...=..\'s`..x..|

00000090  f7 0d 01 01 01 05 00 03  81 8d 00 30 81 89 02 81  |...........0....|
000000a0  81 00 ba 6f aa 86 bd cf  bf 9f f2 ef 5c 94 60 78  |...o........\.`x|
000000b0  6f e8 13 f2 d1 96 6f cd  d9 32 6e 22 37 ce 41 f9  |o.....o..2n"7.A.|
000000c0  ca 5d 29 ac e1 27 da 61  a2 ee 81 cb 10 c7 df 34  |.])..'.a.......4|
000000d0  58 95 86 e9 3d 19 e6 5c  27 73 60 c8 8d 78 02 f4  |X...=..\'s`..x..|

00000090  f7 0d 01 01 01 05 00 03  81 8d 00 30 81 89 02 81  |...........0....|
000000a0  81 00 ba 6f aa 86 bd cf  bf 9f f2 ef 5c 94 60 78  |...o........\.`x|
000000b0  6f e8 13 f2 d1 96 6f cd  d9 32 6e 22 37 ce 41 f9  |o.....o..2n"7.A.|
000000c0  ca 5d 29 ac e1 27 da 61  a2 ee 81 cb 10 c7 df 34  |.])..'.a.......4|
000000d0  58 95 86 e9 3d 19 e6 5c  27 73 60 c8 8d 78 02 f4  |X...=..\'s`..x..|

        .addModifiers(Modifier.PRIVATE)
        .returns(void.class)
        .addParameter(String.class, "className")
        .addStatement("$1N._LDC($2N(className))", METHOD_VISITOR_FIELD, BINARY_CLASS_NAME_OF)
        .build();

    private static final FieldSpec METADATA_FIELD =