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authorGeorge Spelvin <linux@horizon.com>2012-10-04 17:12:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-06 03:04:49 +0900
commitcb239d0a97d573150d6106a92c0641da0d03f6a1 (patch)
tree7557b629f6bf1dce2ee2b7953123a532040fb1ba /lib/vsprintf.c
parent2359172a75986359ce9cf041a9aca6a32cdf8779 (diff)
downloadlinux-stericsson-cb239d0a97d573150d6106a92c0641da0d03f6a1.tar.gz
lib: vsprintf: optimize put_dec_trunc8()
If you're going to have a conditional branch after each 32x32->64-bit multiply, might as well shrink the code and make it a loop. This also avoids using the long multiply for small integers. (This leaves the comments in a confusing state, but that's a separate patch to make review easier.) Signed-off-by: George Spelvin <linux@horizon.com> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Rabin Vincent <rabin@rab.in> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/vsprintf.c')
-rw-r--r--lib/vsprintf.c22
1 files changed, 6 insertions, 16 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 8cb7635b2ce3..c2236f14640f 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -174,22 +174,12 @@ char *put_dec_trunc8(char *buf, unsigned r)
unsigned q;
/* Copy of previous function's body with added early returns */
- q = (r * (uint64_t)0x1999999a) >> 32;
- *buf++ = (r - 10 * q) + '0'; /* 2 */
- if (q == 0)
- return buf;
- r = (q * (uint64_t)0x1999999a) >> 32;
- *buf++ = (q - 10 * r) + '0'; /* 3 */
- if (r == 0)
- return buf;
- q = (r * (uint64_t)0x1999999a) >> 32;
- *buf++ = (r - 10 * q) + '0'; /* 4 */
- if (q == 0)
- return buf;
- r = (q * (uint64_t)0x1999999a) >> 32;
- *buf++ = (q - 10 * r) + '0'; /* 5 */
- if (r == 0)
- return buf;
+ while (r >= 10000) {
+ q = r + '0';
+ r = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = q - 10*r;
+ }
+
q = (r * 0x199a) >> 16;
*buf++ = (r - 10 * q) + '0'; /* 6 */
if (q == 0)