lkml.org 
[lkml]   [2015]   [May]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/2] lib/vsprintf.c: Simplify uuid_string()
From a53aa64b7b508d1f7cddbad556fb94f2c9c0191f Mon Sep 17 00:00:00 2001
From: George Spelvin <linux@horizon.com>
Date: Mon, 11 May 2015 13:05:55 -0400
Subject: [PATCH 1/2] lib/vsprintf.c: Simplify uuid_string()

Rather than have a second pass to upcase the buffer, just make the
hex lookup table variable.

I suspect it's a speedup, but since this is not hot code, the important
part is that it shrinks the function from 332 to 256 bytes.

Signed-off-by: George Spelvin <linux@horizon.com>
---
With apologies for the un-compilable intermediate state of the draft.

lib/vsprintf.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 452e4a16..4c4f9055 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1270,21 +1270,23 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
static const u8 be[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
static const u8 le[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
const u8 *index = be;
- bool uc = false;
+ const char *hex = hex_asc;

switch (*(++fmt)) {
case 'L':
- uc = true; /* fall-through */
+ hex = hex_asc_upper; /* fall-through */
case 'l':
index = le;
break;
case 'B':
- uc = true;
+ hex = hex_asc_upper;
break;
}

for (i = 0; i < 16; i++) {
- p = hex_byte_pack(p, addr[index[i]]);
+ u8 byte = addr[index[i]];
+ *p++ = hex[byte >> 4];
+ *p++ = hex[byte & 0x0f];
switch (i) {
case 3:
case 5:
@@ -1297,13 +1299,6 @@ char *uuid_string(char *buf, char *end, const u8 *addr,

*p = 0;

- if (uc) {
- p = uuid;
- do {
- *p = toupper(*p);
- } while (*(++p));
- }
-
return string(buf, end, uuid, spec);
}

--
2.1.4


\
 
 \ /
  Last update: 2015-05-11 22:21    [W:0.071 / U:46.632 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site