/*	$NetBSD: strspn.c,v 1.2 2018/02/04 01:13:45 mrg Exp $	*/

/*-
 * Copyright (c) 2008 Joerg Sonnenberger
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifdef _KERNEL
#include <sys/libkern.h>
#include <limits.h>
#else
#include <assert.h>
#include <inttypes.h>
#include <limits.h>
#include <string.h>
#endif

#if ULONG_MAX != 0xffffffffffffffffull

size_t strspn(const char *s, const char *charset) {
  static const uint8_t idx[8] = {1, 2, 4, 8, 16, 32, 64, 128};
  uint8_t set[32];
  const char *t;
#define UC(a) ((unsigned int)(unsigned char)(a))

  if (charset[0] == '\0')
    return 0;
  if (charset[1] == '\0') {
    for (t = s; *t != '\0'; ++t) {
      if (*t != *charset)
        break;
    }
    return t - s;
  }

  (void)memset(set, 0, sizeof(set));

  for (; *charset != '\0'; ++charset)
    set[UC(*charset) >> 3] |= idx[UC(*charset) & 7];

  for (t = s; *t != '\0'; ++t)
    if ((set[UC(*t) >> 3] & idx[UC(*t) & 7]) == 0)
      break;
  return t - s;
}

#else

/* 64 bit system, use four 64 bits registers for bitmask */

static size_t strspn_x(const char *s_s, const char *charset_s,
                       unsigned long invert) {
  const unsigned char *s = (const unsigned char *)s_s;
  const unsigned char *charset = (const unsigned char *)charset_s;
  unsigned long m_0, m_4, m_8, m_c;
  unsigned char ch, next_ch;
  unsigned long bit;
  unsigned long check;
  size_t count;

  /* Four 64bit registers have one bit for each character value */
  m_0 = 0;
  m_4 = 0;
  m_8 = 0;
  m_c = 0;

  for (ch = *charset; ch != 0; ch = next_ch) {
    next_ch = *++charset;
    bit = 1ul << (ch & 0x3f);
    if (__predict_true(ch < 0x80)) {
      if (ch < 0x40)
        m_0 |= bit;
      else
        m_4 |= bit;
    } else {
      if (ch < 0xc0)
        m_8 |= bit;
      else
        m_c |= bit;
    }
  }

  /* For strcspn() we just invert the validity set */
  m_0 ^= invert;
  m_4 ^= invert;
  m_8 ^= invert;
  m_c ^= invert;

  /*
   * We could do remove the lsb from m_0 to terminate at the
   * end of the input string.
   * However prefetching the next char is benifitial and we must
   * not read the byte after the \0 - as it might fault!
   * So we take the 'hit' of the compare against 0.
   */

  ch = *s++;
  for (count = 0; ch != 0; ch = next_ch) {
    next_ch = s[count];
    if (__predict_true(ch < 0x80)) {
      check = m_0;
      if (ch >= 0x40)
        check = m_4;
    } else {
      check = m_8;
      if (ch >= 0xc0)
        check = m_c;
    }
    if (!((check >> (ch & 0x3f)) & 1))
      break;
    count++;
  }
  return count;
}

size_t strspn(const char *s, const char *charset) {
  return strspn_x(s, charset, 0);
}

size_t strcspn(const char *s, const char *charset) {
  return strspn_x(s, charset, ~0ul);
}
#endif
