memchr.c

来自「test file nucleus source」· C语言 代码 · 共 85 行

/*************************************************************************
*
*               Copyright Mentor Graphics Corporation 2002
*                         All Rights Reserved.
*
* THIS WORK CONTAINS TRADE SECRET AND PROPRIETARY INFORMATION WHICH IS
* THE PROPERTY OF MENTOR GRAPHICS CORPORATION OR ITS LICENSORS AND IS
* SUBJECT TO LICENSE TERMS.
*
*************************************************************************/

/*************************************************************************
* FILE NAME                                     VERSION
*
*       memchr.c                                Nucleus Common Library 1.1
*
* DESCRIPTION
*
*       This file contains the implementation of NCL_memchr.
*
* DATA STRUCTURES
*
*       None.
*
* FUNCTIONS
*
*       NCL_memchr
*
* DEPENDENCIES
*
*       ncl.h
*       string.h
*       nucleus.h
*
************************************************************************/

#define NU_NCL_SOURCE_FILE

#include "ncl\inc\ncl.h"
#include "ncl\inc\string.h"
#include "plus\nucleus.h"                                /* MMU Support */

/*************************************************************************
*
*   FUNCTION
*
*       NCL_strchr
*
*   DESCRIPTION
*
*       Return a pointer to first occurrence of c in s or 0 if s does not
*       contain c.  If c==0 it returns a pointer to the string's nul
*       character.
*
*   INPUTS
*
*       s                   Memory to search within.
*       c                   Values to search for.
*       n                   Number of bytes to search.
*
*   OUTPUTS
*
*       void*               Pointer to first occurance of c in s or 0 if
*                             s does not contain c.
*
*************************************************************************/

void *NCL_memchr (const void *s, int c, size_t n)
{
    register unsigned char  val = (unsigned char)  c;
    register unsigned char *ptr = (unsigned char*) s;
    register unsigned char *end = ptr + n;

    while (ptr < end)
    {
        if (*ptr++ == val)
        {
            return ((void*) (ptr-1));
        }
    }

    return (NULL);
}