[PATCH]: improved strnicmp in lib/string.c
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From: Soumyadip Das Mahapatra on 7 May 2008 14:30 This is somewhat improved version of strnicmp() function in lib/string.c. I have implemented binary comparison rather than linear one(which was in the older version). I am appending the patch bellow --- 2.6.25-vanilla/lib/string.c 2008-04-17 08:19:44.000000000 +0530 +++ 2.6.25-hacked/lib/string.c 2008-05-07 23:31:57.000000000 +0530 @@ -1,24 +1,3 @@ -/* - * linux/lib/string.c - * - * Copyright (C) 1991, 1992 Linus Torvalds - */ - -/* - * stupid library routines.. The optimized versions should generally be found - * as inline code in <asm-xx/string.h> - * - * These are buggy as well.. - * - * * Fri Jun 25 1999, Ingo Oeser <ioe(a)informatik.tu-chemnitz.de> - * - Added strsep() which will replace strtok() soon (because strsep() is - * reentrant and should be faster). Use only strsep() in new code, please. - * - * * Sat Feb 09 2002, Jason Thomas <jason(a)topic.com.au>, - * Matthew Hawkins <matt(a)mh.dropbear.id.au> - * - Kissed strtok() goodbye - */ - #include <linux/types.h> #include <linux/string.h> #include <linux/ctype.h> @@ -31,32 +10,43 @@ * @s2: The other string * @len: the maximum number of characters to compare */ +/* This is somewhat faster + * method compared to the + * olderone (in case of a large string) + */ int strnicmp(const char *s1, const char *s2, size_t len) { - /* Yes, Virginia, it had better be unsigned */ - unsigned char c1, c2; - - c1 = c2 = 0; - if (len) { - do { - c1 = *s1; - c2 = *s2; - s1++; - s2++; - if (!c1) - break; - if (!c2) - break; - if (c1 == c2) - continue; - c1 = tolower(c1); - c2 = tolower(c2); - if (c1 != c2) + /* Yes, i am keeping 'em unsigned too */ + unsigned char c1, c2, c3, c4; + unsigned count = 0; + int flag = -1; + + c1 = c2 = c3 = c4 = 0; + + if(len > 0) + { + for(; count <= len/2; count++) + { + c1 = tolower(s1[count]); // well, we + c2 = tolower(s2[count]); // are ignoring + c3 = tolower(s1[len-count-1]); // cases + c4 = tolower(s2[len-count-1]); // thats why + + if(c1 == c2) + { + if(c3 != c4) + { + flag = 1; + break; + } + } + else break; - } while (--len); + flag = 0; + } } - return (int)c1 - (int)c2; -} + return flag; // return 0 for matching and +} // nonzero for mismatch EXPORT_SYMBOL(strnicmp); #endif Meet people who discuss and share your passions. Go to http://in.promos.yahoo.com/groups/bestofyahoo/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |