From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Mon, 16 Jul 2007 06:41:54 +0000 (-0700)
Subject: vsprintf.c: optimizing, part 1 (easy and obvious stuff)
X-Git-Tag: v2.6.23-rc1~798
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b39a734097d5095d63eb9c709a6aaf965633bb01;p=pandora-kernel.git

vsprintf.c: optimizing, part 1 (easy and obvious stuff)

* There is no point in having full "0...9a...z" constant vector,
  if we use only "0...9a...f" (and "x" for "0x").

* Post-decrement usually needs a few more instructions, so use
  pre decrement instead where makes sense:
-       while (i < precision--) {
+       while (i <= --precision) {

* if base != 10 (=> base 8 or 16), we can avoid using division
  in a loop and use mask/shift, obtaining much faster conversion.
  (More complex optimization for base 10 case is in the second patch).

Overall, size vsprintf.o shows ~80 bytes smaller text section
with this patch applied.

Signed-off-by: Douglas W Jones <jones@cs.uiowa.edu>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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