translating to stackless c

9.9: adda/translating to stackless c:

. translating to stackless c means that adda is in control of the user stack,

except that trusted code can be called from c.

. untrusted functions are defined as labeled sections of main,

. for each call:

( stack arg

, goto label

, have macros translate each symbol into stack/rec/trailer ptr expression

, end of routine has a return routine

that unloads arg and goes to stacked return address .

)

. can c do all of that?

need to store address of a label .

label: ptr = &label . test .

. stackless could thwart the c`compiler's usual optimizations,

so adda may balance control with efficiency

by just putting a limit on recursion depth .

. to watch and limit recursion depth,

adda builds a call tree,

and if there are any cycles in the tree

(indicating direct or indirect recursion

-- potentially endless stack usage)

then routines in the cycling groups

open by incr'ing a global"[call depth],

and close by decr'ing it .

. the open or close must also test whether

[call depth] > [max depth];

if so, then it returns .