Re: [patch 2.6.26-mmotm] rtc: BCD codeshrink - Kernel

This is a discussion on Re: [patch 2.6.26-mmotm] rtc: BCD codeshrink - Kernel ; On Tue, 1 Jul 2008 23:41:01 -0700 David Brownell wrote: > This updates to define the key routines as constant > functions, which the macros will then call. Newer code can now > call bcd2bin() instead of SCREAMING BCD2BIN() TO ...

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Thread: Re: [patch 2.6.26-mmotm] rtc: BCD codeshrink

  1. Re: [patch 2.6.26-mmotm] rtc: BCD codeshrink

    On Tue, 1 Jul 2008 23:41:01 -0700 David Brownell wrote:

    > This updates to define the key routines as constant
    > functions, which the macros will then call. Newer code can now
    > call bcd2bin() instead of SCREAMING BCD2BIN() TO THE FOUR WINDS.
    >
    > This lets each driver shrink their codespace by using N function
    > calls to a single (global) copy of those routines, instead of N
    > inlined copies of these functions per driver.
    >
    > These routines aren't used in speed-critical code. Almost all
    > callers are in the RTC framework. Typical per-driver savings is
    > near 300 bytes.
    >
    > Signed-off-by: David Brownell
    > Acked-by: Adrian Bunk
    > ---
    > include/linux/bcd.h | 9 +++++++--
    > lib/Makefile | 2 +-
    > lib/bcd.c | 14 ++++++++++++++
    > 3 files changed, 22 insertions(+), 3 deletions(-)
    >
    > --- a/include/linux/bcd.h 2008-06-30 16:44:26.000000000 -0700
    > +++ b/include/linux/bcd.h 2008-06-30 21:38:24.000000000 -0700
    > @@ -10,8 +10,13 @@
    > #ifndef _BCD_H
    > #define _BCD_H
    >
    > -#define BCD2BIN(val) (((val) & 0x0f) + ((val)>>4)*10)
    > -#define BIN2BCD(val) ((((val)/10)<<4) + (val)%10)
    > +#include
    > +
    > +unsigned bcd2bin(unsigned char val) __attribute_const__;
    > +unsigned char bin2bcd(unsigned val) __attribute_const__;
    > +
    > +#define BCD2BIN(val) bcd2bin(val)
    > +#define BIN2BCD(val) bin2bcd(val)


    It'd be good to nuke these things now.

    Unfortunately you didn't cc the list where nukers lurk. Please do cc
    linux-kernel on kernel-wide patches.

    > /* backwards compat */
    > #define BCD_TO_BIN(val) ((val)=BCD2BIN(val))
    > --- a/lib/Makefile 2008-06-30 16:44:26.000000000 -0700
    > +++ b/lib/Makefile 2008-06-30 21:38:24.000000000 -0700
    > @@ -13,7 +13,7 @@ lib-$(CONFIG_SMP) += cpumask.o
    >
    > lib-y += kobject.o kref.o klist.o
    >
    > -obj-y += div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
    > +obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
    > bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o
    >
    > ifeq ($(CONFIG_DEBUG_KOBJECT),y)
    > --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    > +++ b/lib/bcd.c 2008-06-30 21:38:24.000000000 -0700
    > @@ -0,0 +1,14 @@
    > +#include
    > +#include
    > +
    > +unsigned bcd2bin(unsigned char val)
    > +{
    > + return (val & 0x0f) + (val >> 4) * 10;
    > +}
    > +EXPORT_SYMBOL(bcd2bin);
    > +
    > +unsigned char bin2bcd(unsigned val)
    > +{
    > + return ((val / 10) << 4) + val % 10;
    > +}
    > +EXPORT_SYMBOL(bin2bcd);

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  2. Re: [patch 2.6.26-mmotm] rtc: BCD codeshrink

    On Wed, Jul 02, 2008 at 01:45:02AM -0700, Andrew Morton wrote:
    > On Tue, 1 Jul 2008 23:41:01 -0700 David Brownell wrote:
    >
    > > This updates to define the key routines as constant
    > > functions, which the macros will then call. Newer code can now
    > > call bcd2bin() instead of SCREAMING BCD2BIN() TO THE FOUR WINDS.
    > >
    > > This lets each driver shrink their codespace by using N function
    > > calls to a single (global) copy of those routines, instead of N
    > > inlined copies of these functions per driver.
    > >
    > > These routines aren't used in speed-critical code. Almost all
    > > callers are in the RTC framework. Typical per-driver savings is
    > > near 300 bytes.
    > >
    > > Signed-off-by: David Brownell
    > > Acked-by: Adrian Bunk
    > > ---
    > > include/linux/bcd.h | 9 +++++++--
    > > lib/Makefile | 2 +-
    > > lib/bcd.c | 14 ++++++++++++++
    > > 3 files changed, 22 insertions(+), 3 deletions(-)
    > >
    > > --- a/include/linux/bcd.h 2008-06-30 16:44:26.000000000 -0700
    > > +++ b/include/linux/bcd.h 2008-06-30 21:38:24.000000000 -0700
    > > @@ -10,8 +10,13 @@
    > > #ifndef _BCD_H
    > > #define _BCD_H
    > >
    > > -#define BCD2BIN(val) (((val) & 0x0f) + ((val)>>4)*10)
    > > -#define BIN2BCD(val) ((((val)/10)<<4) + (val)%10)
    > > +#include
    > > +
    > > +unsigned bcd2bin(unsigned char val) __attribute_const__;
    > > +unsigned char bin2bcd(unsigned val) __attribute_const__;
    > > +
    > > +#define BCD2BIN(val) bcd2bin(val)
    > > +#define BIN2BCD(val) bin2bcd(val)

    >
    > It'd be good to nuke these things now.
    >...


    Unless David is faster I plan to do this after the patch went into
    Linus' tree.

    E.g. rtc-ramtron-fm3130-rtc-support.patch in 2.6.26-rc5-mm3 adds a new
    user, and it should create less hassle if the actual removal of the
    #define's happens around 2.6.27-rc1 when everything is merged into
    Linus' tree.

    cu
    Adrian

    --

    "Is there not promise of rain?" Ling Tan asked suddenly out
    of the darkness. There had been need of rain for many days.
    "Only a promise," Lao Er said.
    Pearl S. Buck - Dragon Seed

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