b -= 1 => flags, nf := tmp.7,
tmp2 = tmp + [[c - 1] nnnD and 0xff],
pf := parity of [[tmp2 nnnD and 0x07] XOr xor b],
hf := cf := tmp2 > 255
b -= 1 => flags, nf := tmp.7,
tmp2 := tmp + [[c + 1] nnnD and 0xff],
pf := parity of [[tmp2 nnnD and 0x07] XOr xor b],
hf := cf := tmp2 > 255
b -= 1 => flags, nf := tmp.7, tmp2 = tmp + l,
pf := parity of [[tmp2 nnnD and 0x07] XOr xor b],
hf := cf := tmp2 > 255
b -= 1 => flags, nf := tmp.7, tmp2 = tmp + l,
pf := parity of [[tmp2 nnnD and 0x07] XOr xor b],
hf := cf := tmp2 > 255