genius_strchr.c

/**
  Returns the first occurrence of a Null-terminated ASCII character
  in a Null-terminated ASCII string.

  This function scans the contents of the ASCII string specified by s
  and returns the first occurrence of c. If c is not found in s,
  then NULL is returned. If the length of c is zero, then s is returned.

  @param  s               The pointer to a Null-terminated ASCII string.
  @param  c               The pointer to a Null-terminated ASCII character to search for.

  @retval NULL            If the c does not appear in s.
  @retval others          If there is a match return the first occurrence of c.
                          If the length of c is zero,return s.

**/
char *
strchr (
  const char  *s,
  int         c
  )
{
  char  pattern[2];

  pattern[0] = (CHAR8)c;
  pattern[1] = 0;
  return AsciiStrStr (s, pattern);
}

/**
  Returns the last occurrence of a Null-terminated ASCII character
  in a Null-terminated ASCII string.

  This function scans the contents of the ASCII string specified by s
  and returns the last occurrence of c. If c is not found in s,
  then NULL is returned. If the length of c is zero, then s is returned.

  @param  s               The pointer to a Null-terminated ASCII string.
  @param  c               The pointer to a Null-terminated ASCII character to search for.

  @retval NULL            If the c does not appear in s.
  @retval others          If there is a match return the last occurrence of c.
                          If the length of c is zero,return s.
**/
char *
strrchr (
  const char  *s,
  int         c
  )
{
  char         pattern[2];
  CONST CHAR8  *LastMatch;
  CONST CHAR8  *StringTmp;
  CONST CHAR8  *SearchString;

  pattern[0]   = (CHAR8)c;
  pattern[1]   = 0;
  SearchString = pattern;

  //
  // Return NULL if both strings are less long than PcdMaximumAsciiStringLength
  //
  if ((AsciiStrSize (s) == 0) || (AsciiStrSize (SearchString) == 0)) {
    return NULL;
  }

  if (*SearchString == '\0') {
    return (CHAR8 *)s;
  }

  LastMatch = NULL;
  do {
    StringTmp = AsciiStrStr (s, SearchString);

    if (StringTmp == NULL) {
      break;
    }

    LastMatch = StringTmp;
    s         = StringTmp + 1;
  } while (s != NULL);

  return (CHAR8 *)LastMatch;
}