Indirect Threaded Forth, host functions

Register usage

IP:     r25:r24
W:      r23:r22
SP: Y   r29:r28
RP: SP
TOS: X  r27:r26

DOCOL / Enter

IP points to next word in the caller W points to CFA

Host

::host::

host-itc.ft

:noname        t, ; is t,call
:noname        talign
               there tlast @ t, tlast !
               there >target pack$ c@ 1+ tallot talign ; is thead