From fe3e1d8cca8bb3162e0324491feeedc7fa5c97e9 Mon Sep 17 00:00:00 2001 From: George Spelvin Date: Wed, 26 Sep 2012 11:34:17 +1000 Subject: [PATCH] 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 Cc: Denys Vlasenko Cc: Michal Nazarewicz Signed-off-by: Andrew Morton --- lib/vsprintf.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 8cb7635b2ce3..f58fc4b1eaf0 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -174,20 +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 */ + 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; -- 2.39.5