| Message ID | 1314133621-6488-5-git-send-email-jason.hobbs@calxeda.com |
|---|---|
| State | Accepted |
| Commit | 93337abbfe2951c63a4e7b450da1848c6c69217f |
| Headers | show |
On Tuesday, August 23, 2011 17:06:52 Jason Hobbs wrote: > Existing ctype checks are implemented using a 256 byte lookup table, > allowing each character to be in any of 8 character classes. Since there > are 8 existing character classes without the blank class, I implemented > isblank without using the lookup table. Since there are only two blank > characters - tab and space - this is a more reasonable approach than > doubling the size of the lookup table to accommodate one more class. and isspace() doesnt work because ... ? -mike
On Tue, Aug 23, 2011 at 05:40:35PM -0400, Mike Frysinger wrote: > On Tuesday, August 23, 2011 17:06:52 Jason Hobbs wrote: > > Existing ctype checks are implemented using a 256 byte lookup table, > > allowing each character to be in any of 8 character classes. Since there > > are 8 existing character classes without the blank class, I implemented > > isblank without using the lookup table. Since there are only two blank > > characters - tab and space - this is a more reasonable approach than > > doubling the size of the lookup table to accommodate one more class. > > and isspace() doesnt work because ... ? Because isspace matches characters other than tab and space, like end of line, which isn't always desired. Jason
diff --git a/include/linux/ctype.h b/include/linux/ctype.h index 6dec944..42f9305 100644 --- a/include/linux/ctype.h +++ b/include/linux/ctype.h @@ -31,6 +31,12 @@ extern const unsigned char _ctype[]; #define isupper(c) ((__ismask(c)&(_U)) != 0) #define isxdigit(c) ((__ismask(c)&(_D|_X)) != 0) +/* + * Rather than doubling the size of the _ctype lookup table to hold a 'blank' + * flag, just check for space or tab. + */ +#define isblank(c) (c == ' ' || c == '\t') + #define isascii(c) (((unsigned char)(c))<=0x7f) #define toascii(c) (((unsigned char)(c))&0x7f)
Existing ctype checks are implemented using a 256 byte lookup table, allowing each character to be in any of 8 character classes. Since there are 8 existing character classes without the blank class, I implemented isblank without using the lookup table. Since there are only two blank characters - tab and space - this is a more reasonable approach than doubling the size of the lookup table to accommodate one more class. Signed-off-by: Jason Hobbs <jason.hobbs@calxeda.com> --- new in v4 include/linux/ctype.h | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-)