math support in busybox shells

[walter harms]

Hi mike,
dc has some nice math and is a actualy a small utility. perhaps you can
add that math cababilities to ash ?
that would be a real enhancement over other shells.

re,
 wh


Mike Frysinger schrieb:
> ash is the only shell that has math support.  rather than rewrite a new one 
> from scratch for hush, i'm wondering if we can split it out of ash so that it 
> is shared among any/all shells.  more of a parsing library.  i thought about 
> simply wiring up builtin_expr() to do the parsing, but the syntax and 
> operators that it supports is more limited than what is required in the shell.
> 
> looking at ash shows that the math code apparently used to be a sep yacc file, 
> but then the C output of it was merged and cut down.  hopefully this means 
> that it isnt too hard to split back out.
> 
> thinking about it at a higher level, the only thing the engine needs to do is 
> to get and set variables ... all other shell related parsing should already be 
> done at that point.  and the return value should always be a signed long int.  
> thoughts ?
> -mike
>