181 lines
4.4 KiB
C
181 lines
4.4 KiB
C
/***
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*strspn.c - find length of initial substring of chars from a control string
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines strspn() - finds the length of the initial substring of
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* a string consisting entirely of characters from a control string.
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*
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* defines strcspn()- finds the length of the initial substring of
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* a string consisting entirely of characters not in a control string.
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*
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* defines strpbrk()- finds the index of the first character in a string
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* that is not in a control string
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*
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*Revision History:
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* 06-01-89 JCR C version created.
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* 02-27-90 GJF Fixed calling type, #include <cruntime.h>, fixed
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* copyright.
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* 08-14-90 SBM Removed now redundant #include <stddef.h>
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* 10-02-90 GJF New-style function declarators.
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* 12-04-90 SRW Made it default to compiling for strspn
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* 05-21-93 GJF Used unsigned char pointers to access control and
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* source strings.
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* 09-03-93 GJF Replaced _CALLTYPE1 with __cdecl.
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*
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*******************************************************************************/
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/* Determine which routine we're compiling for (default to STRSPN) */
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#define _STRSPN 1
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#define _STRCSPN 2
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#define _STRPBRK 3
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#if defined(SSTRCSPN)
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#define ROUTINE _STRCSPN
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#elif defined(SSTRPBRK)
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#define ROUTINE _STRPBRK
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#else
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#define ROUTINE _STRSPN
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#endif
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#include <cruntime.h>
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#include <string.h>
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/***
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*int strspn(string, control) - find init substring of control chars
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*
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*Purpose:
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* Finds the index of the first character in string that does belong
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* to the set of characters specified by control. This is
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* equivalent to the length of the initial substring of string that
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* consists entirely of characters from control. The '\0' character
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* that terminates control is not considered in the matching process.
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*
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*Entry:
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* char *string - string to search
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* char *control - string containing characters not to search for
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*
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*Exit:
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* returns index of first char in string not in control
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*
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*Exceptions:
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*
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*******************************************************************************/
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/***
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*int strcspn(string, control) - search for init substring w/o control chars
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*
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*Purpose:
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* returns the index of the first character in string that belongs
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* to the set of characters specified by control. This is equivalent
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* to the length of the length of the initial substring of string
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* composed entirely of characters not in control. Null chars not
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* considered.
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*
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*Entry:
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* char *string - string to search
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* char *control - set of characters not allowed in init substring
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*
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*Exit:
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* returns the index of the first char in string
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* that is in the set of characters specified by control.
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*
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*Exceptions:
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*
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*******************************************************************************/
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/***
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*char *strpbrk(string, control) - scans string for a character from control
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*
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*Purpose:
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* Finds the first occurence in string of any character from
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* the control string.
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*
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*Entry:
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* char *string - string to search in
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* char *control - string containing characters to search for
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*
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*Exit:
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* returns a pointer to the first character from control found
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* in string.
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* returns NULL if string and control have no characters in common.
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*
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*Exceptions:
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*
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*******************************************************************************/
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/* Routine prototype */
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#if ROUTINE == _STRSPN /*IFSTRIP=IGN*/
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size_t __cdecl strspn (
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#elif ROUTINE == _STRCSPN /*IFSTRIP=IGN*/
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size_t __cdecl strcspn (
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#else /* ROUTINE == STRPBRK */
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char * __cdecl strpbrk (
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#endif
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const char * string,
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const char * control
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)
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{
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const unsigned char *str = string;
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const unsigned char *ctrl = control;
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unsigned char map[32];
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int count;
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/* Clear out bit map */
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for (count=0; count<32; count++)
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map[count] = 0;
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/* Set bits in control map */
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while (*ctrl)
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{
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map[*ctrl >> 3] |= (1 << (*ctrl & 7));
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ctrl++;
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}
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#if ROUTINE == _STRSPN /*IFSTRIP=IGN*/
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/* 1st char NOT in control map stops search */
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if (*str)
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{
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count=0;
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while (map[*str >> 3] & (1 << (*str & 7)))
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{
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count++;
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str++;
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}
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return(count);
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}
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return(0);
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#elif ROUTINE == _STRCSPN /*IFSTRIP=IGN*/
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/* 1st char in control map stops search */
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count=0;
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map[0] |= 1; /* null chars not considered */
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while (!(map[*str >> 3] & (1 << (*str & 7))))
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{
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count++;
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str++;
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}
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return(count);
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#else /* (ROUTINE == _STRPBRK) */
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/* 1st char in control map stops search */
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while (*str)
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{
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if (map[*str >> 3] & (1 << (*str & 7)))
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return((char *)str);
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str++;
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}
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return(NULL);
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#endif
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}
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