The patch titled
Subject: lib: vsprintf: optimize put_dec_trunc8()
has been added to the -mm tree. Its filename is
lib-vsprintf-optimize-put_dec_trunc8.patch
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------------------------------------------------------
From: George Spelvin <linux@xxxxxxxxxxx>
Subject: 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@xxxxxxxxxxx>
Cc: Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/vsprintf.c | 20 ++++++--------------
1 file changed, 6 insertions(+), 14 deletions(-)
diff -puN lib/vsprintf.c~lib-vsprintf-optimize-put_dec_trunc8 lib/vsprintf.c
--- a/lib/vsprintf.c~lib-vsprintf-optimize-put_dec_trunc8
+++ a/lib/vsprintf.c
@@ -174,20 +174,12 @@ char *put_dec_trunc8(char *buf, unsigned
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 */
+ while (r >= 10000) {
+ q = r + '0';
+ r = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = q - 10*r;
+ }
+
if (r == 0)
return buf;
q = (r * 0x199a) >> 16;
_
Patches currently in -mm which might be from linux@xxxxxxxxxxx are
lib-vsprintf-optimize-division-by-10-for-small-integers.patch
lib-vsprintf-optimize-division-by-10000.patch
lib-vsprintf-optimize-put_dec_trunc8.patch
lib-vsprintf-fix-broken-comments.patch
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