[Buildroot] [RFC 1/3] pkg-utils: introduce a make-based LOWERCASE function

[Arnout Vandecappelle <arnout@mind.be>]

On 23/03/14 18:43, Thomas Petazzoni wrote:
> Until now, our UPPERCASE function was implemented purely in make for
> performance reasons, but our LOWERCASE function was implemented by
> calling "tr", which was reasonable due to the fact that LOWERCASE was
> rarely used.
> 
> An upcoming change is going to make LOWERCASE used quite a bit more,
> so we turn it into a pure make function.
> 
> Moreover, we want this LOWERCASE function to turn a "_" into a "-" and
> not a ".", so we slightly adjust the existing FROM and TO lists to
> make this possible. This doesn't change the behavior of the UPPERCASE
> macro because both "-" and "." are converted into "_" by this
> function.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  package/pkg-utils.mk | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/package/pkg-utils.mk b/package/pkg-utils.mk
> index 91a1981..8c3e534 100644
> --- a/package/pkg-utils.mk
> +++ b/package/pkg-utils.mk
> @@ -13,7 +13,7 @@
>  # as this macro is used a lot it matters
>  # This works by creating translation character pairs (E.G. a:A b:B)
>  # and then looping though all of them running $(subst from,to,text)
> -[FROM] := a b c d e f g h i j k l m n o p q r s t u v w x y z . -
> +[FROM] := a b c d e f g h i j k l m n o p q r s t u v w x y z - .
>  [TO]   := A B C D E F G H I J K L M N O P Q R S T U V W X Y Z _ _
>  
>  UPPERCASE = $(strip $(eval __tmp := $1) \
> @@ -23,13 +23,12 @@ UPPERCASE = $(strip $(eval __tmp := $1) \
>  	$(__tmp)))) \
>  	$(__tmp))
>  
> -# LOWERCASE macro -- transforms its arguments to lowercase
> -# The above non-tr implementation is not needed, because LOWERCASE is not
> -# called very often
> -
> -define LOWERCASE
> -$(shell echo $1 | tr '[:upper:]' '[:lower:]')
> -endef
> +LOWERCASE = $(strip $(eval __tmp := $1) \
> +	$(foreach c, $(join $(addsuffix :,$([TO])),$([FROM])), \
> +		$(eval __tmp :=	\
> +		$(subst $(word 1,$(subst :, ,$c)),$(word 2,$(subst :, ,$c)),\
> +	$(__tmp)))) \
> +	$(__tmp))

 I get a further 30-40% speedup with the following definition:


define caseconvert-helper
$(1) = $$(strip \
	$$(eval __tmp := $$(1))\
	$(foreach c, $(2),\
		$$(eval __tmp := $$(subst $(word 1,$(subst :, ,$c)),$(word 2,$(subst :, ,$c)),$$(__tmp))))\
	$$(__tmp))
endef

$(eval $(call caseconvert-helper,UPPERCASE,$(join $(addsuffix :,$([FROM])),$([TO]))))
$(eval $(call caseconvert-helper,LOWERCASE,$(join $(addsuffix :,$([TO])),$([FROM]))))


(this avoids re-evaluating the foreach in every call).


 Regards,
 Arnout

>  
>  #
>  # Manipulation of .config files based on the Kconfig
> 


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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