Re: Math and GMake

[Ken Smith]

On Sat, Sep 25, 2004 at 08:30:59AM +0200, Tzafrir Cohen wrote:
> On Fri, Sep 24, 2004 at 05:08:21PM -0400, Ken Smith wrote:
> > Is there a simple way to do math in GMake?  I am currently doing
> > something like this.
> > 
> > # GNUmakefile
> > os_math = $(shell echo "$(1)" | bc)
> 
> bash has $(( )) for math calculations. I'm not sure if this is also
> supported by other bourne shells, though.
> 
> > os_add = $(call os_math,$(1)+$(2))          
> > ge = $(shell [[ "$(1)" -ge "$(2)" ]] && echo t)
> > 
> > range = $(if $(call ge,$(strip $(2)),$(strip $(1))),$(call range,$(call 
> > os_add,$(1),1),$(2),$(3) $(1)),$(strip $(3)))
> > 
> > VAR=$(call range,1,10)
> > 
> > all:
> >         @echo VAR=$(VAR)
> > # end GNUmakefile
> 
> my gmake 3.79.1 complains about the recusive variable range, and quits.
> 
> > 
> > An strace of gmake running on the above example shows how painfully slow
> > this code will make a build which uses it at all.  (How many times will
> > os_add fork?  Yikes.)  I would like to know if the above can be done
> > using only GMake primitives?  Maybe?  Please?
> > 
> > I'll also appreciate hearing any other suggestions or optimizations.
> > Can any clever mailgroup participant think of a nonrecursive way to
> > write the range function?
> 
> Why not simply use seq(1) ?

I knew there had to be a simple command for this somewhere.  Thanks.
But my problem is more general.  I cannot use bash or zsh where the
double parentheses notation is available.  I would also like to come
up with a better way to do math in gmake.

Also, I forgot to mention that the the above example does require gmake
3.80 or later.

Thanks for your help.
Ken