/***
*strspn.c - find length of initial substring of chars from a control string
*
*       Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines strspn() - finds the length of the initial substring of
*       a string consisting entirely of characters from a control string.
*
*       defines strcspn()- finds the length of the initial substring of
*       a string consisting entirely of characters not in a control string.
*
*       defines strpbrk()- finds the index of the first character in a string
*       that is not in a control string
*
*******************************************************************************/
#include <string.h>
/***
*int strcspn(string, control) - search for init substring w/o control chars
*
*Purpose:
*       returns the index of the first character in string that belongs
*       to the set of characters specified by control.  This is equivalent
*       to the length of the length of the initial substring of string
*       composed entirely of characters not in control.  Null chars not
*       considered.
*
*Entry:
*       char *string - string to search
*       char *control - set of characters not allowed in init substring
*
*Exit:
*       returns the index of the first char in string
*       that is in the set of characters specified by control.
*
*Exceptions:
*
*******************************************************************************/

size_t strcspn(const char * string, const char * control)
{
	const unsigned char *str = (unsigned char *)string;
	const unsigned char *ctrl = (unsigned char *)control;

	unsigned char map[32];
	int count;

	/* Clear out bit map */
	for(count=0; count<32; count++)
		map[count] = 0;

	/* Set bits in control map */
	while(*ctrl)
	{
		map[*ctrl >> 3] |= (1 << (*ctrl & 7));
		ctrl++;
	}

	/* 1st char in control map stops search */
	count=0;
	map[0] |= 1;    /* null chars not considered */
	while(!(map[*str >> 3] & (1 << (*str & 7))))
	{
		count++;
		str++;
	}

	return count;
}
