Re: Avoid treating the stack as an array [Re: "Back & Forth" is back!]

On 16/09/2024 8:13 pm, mhx wrote:

[..]
FORTH> tnb
\ no locals:  5ns/call.
\    locals:  18.2ns/call.
\    globals: 6ns/call.
\ no locals2: 21.9ns/call. ok
 
This appears not to be a good idea.
The root cause is piling up too many
items on the F-stack (exceeding the
hardware FPU stack limits).

FVALUEs may be the way to go for hardware stack.
Is this any better?

: tri_mf ( f: x a b c -- mv)
  3 fpick ( x) 3 fpick ( x a) f>=
  3 fpick ( x) 2 fpick ( x b) f< and if
    fdrop               \ x a b
    frot 2 fpick  f-    \ a b x-a
    fswap frot f-       \ x-a b-a
    f/ exit
  then
  3 fpick ( x) 2 fpick ( x b) f>=
  3 fpick ( x) 1 fpick ( x c) f< and if
    frot fdrop          \ x b c
    frot fover fswap f- \ b c c-x
    fswap frot f-       \ c-x c-b
    f/ exit
  then
  fdrop fdrop fdrop fdrop  0e
;