| ~128 = i + i0, i0 < 0, j ≤ 0, i0 * 256 + j < 0, 0 ≤ ub2i(i2b(j + 255)), i0 < ~128, abs(j) < 256, i0 * 256 + j ≤ ~256, ub2i(i2b(j + 255)) < 256, i * 256 ≤ 255 + j ⊦ ub2i(i2b(j + 255)) + 256 * b2i(i2b(i0)) = (i0 * 256 + j) + 255 |
~128 = i + i0, i0 < 0, j ≤ 0, i0 * 256 + j < 0, 0 ≤ ub2i(i2b(j + 255)), i0 < i + i0, abs(j) < 256, i0 * 256 + j ≤ ~256, ub2i(i2b(j + 255)) < 256, i * 256 ≤ 255 + j ⊦ ub2i(i2b(j + 255)) + 256 * b2i(i2b(i0)) = (i0 * 256 + j) + 255