aboutsummaryrefslogtreecommitdiffstats
path: root/lib
diff options
context:
space:
mode:
authorGeorge Spelvin <linux@horizon.com>2012-10-04 20:12:27 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-05 14:04:48 -0400
commite49317d415f5a44bad8377a208d61902d752303e (patch)
tree2033f7152350144068f0bbe22a4735fc12fd4f30 /lib
parent6c0c0d4d1080840eabb3d055d2fd81911111c5fd (diff)
lib: vsprintf: optimize division by 10 for small integers
Shrink the reciprocal approximations used in put_dec_full4() based on the comments in put_dec_full9(). Signed-off-by: George Spelvin <linux@horizon.com> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/vsprintf.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 0e337541f005..67e74cbefa90 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -243,13 +243,14 @@ char *put_dec(char *buf, unsigned long long n)
243 243
244/* Second algorithm: valid only for 64-bit long longs */ 244/* Second algorithm: valid only for 64-bit long longs */
245 245
246/* See comment in put_dec_full9 for choice of constants */
246static noinline_for_stack 247static noinline_for_stack
247char *put_dec_full4(char *buf, unsigned q) 248char *put_dec_full4(char *buf, unsigned q)
248{ 249{
249 unsigned r; 250 unsigned r;
250 r = (q * 0xcccd) >> 19; 251 r = (q * 0xccd) >> 15;
251 *buf++ = (q - 10 * r) + '0'; 252 *buf++ = (q - 10 * r) + '0';
252 q = (r * 0x199a) >> 16; 253 q = (r * 0xcd) >> 11;
253 *buf++ = (r - 10 * q) + '0'; 254 *buf++ = (r - 10 * q) + '0';
254 r = (q * 0xcd) >> 11; 255 r = (q * 0xcd) >> 11;
255 *buf++ = (q - 10 * r) + '0'; 256 *buf++ = (q - 10 * r) + '0';