Re: Math and GMake

[Tzafrir Cohen]

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) ?

-- 
Tzafrir Cohen                       +---------------------------+
http://www.technion.ac.il/~tzafrir/ |vim is a mutt's best friend|
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