lkml.org 
[lkml]   [2010]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] vsprintf.c: Reduce sizeof struct printf_spec from 24 to 8 bytes
From
Date
On Sat, 2010-03-06 at 15:58 -0800, Linus Torvalds wrote:
> And no, I guess we don't really need to make it 32-bit. Fitting in 64 bits
> would already be a big improvement over what we have now.

Reducing the size of struct printf_spec is a good thing
because multiple instances are commonly passed on stack.

It's possible for type to be u8 and field_width to be s8,
but this is likely small enough for now.

Signed-off-by: Joe Perches <joe@perches.com>
---
lib/vsprintf.c | 22 ++++++++++++----------
1 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index af4aaa6..fdee7f7 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -408,12 +408,12 @@ enum format_type {
};

struct printf_spec {
- enum format_type type;
- int flags; /* flags to number() */
- int field_width; /* width of output field */
- int base;
- int precision; /* # of digits/chars */
- int qualifier;
+ u16 type;
+ s16 field_width; /* width of output field */
+ u8 flags; /* flags to number() */
+ u8 base;
+ s8 precision; /* # of digits/chars */
+ u8 qualifier;
};

static char *number(char *buf, char *end, unsigned long long num,
@@ -1333,7 +1333,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
break;

case FORMAT_TYPE_NRCHARS: {
- int qualifier = spec.qualifier;
+ u8 qualifier = spec.qualifier;

if (qualifier == 'l') {
long *ip = va_arg(args, long *);
@@ -1619,7 +1619,7 @@ do { \

case FORMAT_TYPE_NRCHARS: {
/* skip %n 's argument */
- int qualifier = spec.qualifier;
+ u8 qualifier = spec.qualifier;
void *skip_arg;
if (qualifier == 'l')
skip_arg = va_arg(args, long *);
@@ -1885,7 +1885,9 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
char *next;
char digit;
int num = 0;
- int qualifier, base, field_width;
+ u8 qualifier;
+ u8 base;
+ s16 field_width;
bool is_sign;

while (*fmt && *str) {
@@ -1963,7 +1965,7 @@ int vsscanf(const char *buf, const char *fmt, va_list args)
{
char *s = (char *)va_arg(args, char *);
if (field_width == -1)
- field_width = INT_MAX;
+ field_width = SHORT_MAX;
/* first, skip leading white space in buffer */
str = skip_spaces(str);




\
 
 \ /
  Last update: 2010-03-07 02:13    [W:0.202 / U:0.172 seconds]
©2003-2014 Jasper Spaans. Advertise on this site