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Commit e49317d4 authored by George Spelvin's avatar George Spelvin Committed by Linus Torvalds
Browse files

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: default avatarGeorge Spelvin <linux@horizon.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6c0c0d4d

lib/vsprintf.c

+3 −2
Original line number Diff line number Diff line
@@ -243,13 +243,14 @@ char *put_dec(char *buf, unsigned long long n) 


/* Second algorithm: valid only for 64-bit long longs */



/* See comment in put_dec_full9 for choice of constants */

static noinline_for_stack

char *put_dec_full4(char *buf, unsigned q)

{

	unsigned r;

	r      = (q * 0xcccd) >> 19;

	r      = (q * 0xccd) >> 15;

	*buf++ = (q - 10 * r) + '0';

	q      = (r * 0x199a) >> 16;

	q      = (r * 0xcd) >> 11;

	*buf++ = (r - 10 * q)  + '0';

	r      = (q * 0xcd) >> 11;

	*buf++ = (q - 10 * r)  + '0';