; ( n1 -- [ n1 n1 ] | 0) Stack
; R( -- )
; duplicate TOS if non-zero
VE_QDUP:
.db $04, "?dup",0
.dw VE_HEAD
.set VE_HEAD = VE_QDUP
XT_QDUP:
.dw PFA_QDUP
PFA_QDUP:
mov temp0, tosl
or temp0, tosh
breq PFA_QDUP1
savetos
PFA_QDUP1:
rjmp DO_NEXT