`On Fri, 30 Apr 2010 12:34:00 +0300Andy Shevchenko <ext-andriy.shevchenko@nokia.com> wrote:>  /**> + * hex_to_bin - convert a hex digit to its real value> + * @ch: ascii character represents hex digit> + *> + * hex_to_bin() converts one hex digit to its actual value or -1 in case of bad> + * input.> + */> +int hex_to_bin(char ch)> +{> +	if ((ch >= 'a') && (ch <= 'f'))> +		return ch - 'a' + 10;> +	if ((ch >= '0') && (ch <= '9'))> +		return ch - '0';> +	if ((ch >= 'A') && (ch <= 'F'))> +		return ch - 'A' + 10;> +	return -1;> +}> +EXPORT_SYMBOL(hex_to_bin);I had to fiddle with it:- use tolower(), saving 3 bytes!- test the more common case first - it's quicker.diff -puN lib/hexdump.c~lib-introduce-common-method-to-convert-hex-digits-fix lib/hexdump.c--- a/lib/hexdump.c~lib-introduce-common-method-to-convert-hex-digits-fix+++ a/lib/hexdump.c@@ -24,12 +24,11 @@ EXPORT_SYMBOL(hex_asc);  */ int hex_to_bin(char ch) {-	if ((ch >= 'a') && (ch <= 'f'))-		return ch - 'a' + 10;+	ch = tolower(ch); 	if ((ch >= '0') && (ch <= '9')) 		return ch - '0';-	if ((ch >= 'A') && (ch <= 'F'))-		return ch - 'A' + 10;+	if ((ch >= 'a') && (ch <= 'f'))+		return ch - 'a' + 10; 	return -1; } EXPORT_SYMBOL(hex_to_bin);_Yieldingint hex_to_bin(char ch){	ch = tolower(ch);	if ((ch >= '0') && (ch <= '9'))		return ch - '0';	if ((ch >= 'a') && (ch <= 'f'))		return ch - 'a' + 10;	return -1;}`