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SubjectRe: [RESEND PATCH 0/2] Make functions of dev_<level> macros, recursive vsnprintf
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On Sat, 2010-03-06 at 14:57 -0800, Linus Torvalds wrote:
>
> On Sat, 6 Mar 2010, Linus Torvalds wrote:
> >
> > I'm not convinced. We pass that 'printf_spec' around a lot, including
> > nesting. Not as a pointer, either.
>
> Btw, I wonder if those fields could become bitfields, or 'unsigned char'
> etc. That printf_spec really is unnecessarily big. It should _easily_ fit
> in a single register on a 64-bit platform, possibly even a 32-bit one (we
> could limit field width and precision to 5 bits, for example)

I believe 32 bits isn't possible.

type:6
flags:8
width:8
base:6
precision:6
qualifier:8

So maybe something like this:

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);





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