func readprog(b *bufio.Reader, p *liblink.Prog) {
if !undef[p] {
panic("double-def")
}
delete(undef, p)
p.Pc = rdint(b)
p.Lineno = int32(rdint(b))
p.Link = rdprog(b)
p.As = int16(rdint(b))
p.Reg = uint8(rdint(b))
p.Scond = uint8(rdint(b))
p.Width = int8(rdint(b))
readaddr(b, &p.From)
readaddr(b, &p.To)
}