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| author | George Spelvin <linux@horizon.com> | 2012-10-04 17:12:30 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-06 03:04:49 +0900 |
| commit | cb239d0a97d573150d6106a92c0641da0d03f6a1 (patch) | |
| tree | 7557b629f6bf1dce2ee2b7953123a532040fb1ba /lib | |
| parent | 2359172a75986359ce9cf041a9aca6a32cdf8779 (diff) | |
| download | linux-cb239d0a97d573150d6106a92c0641da0d03f6a1.tar.gz linux-cb239d0a97d573150d6106a92c0641da0d03f6a1.tar.bz2 linux-cb239d0a97d573150d6106a92c0641da0d03f6a1.zip | |
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')
| -rw-r--r-- | lib/vsprintf.c | 22 |
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) |