/* Copyright (C) 2000-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Bruno Haible <haible@clisp.cons.org>, 2000.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <stdint.h>

/* Tables indexed by a wide character are compressed through the use

   of a multi-level lookup.  The compression effect comes from blocks

   that don't need particular data and from blocks that can share their

   data.  */

/* Bit tables are accessed by cutting wc in four blocks of bits:

   - the high 32-q-p bits,

   - the next q bits,

   - the next p bits,

   - the next 5 bits.

	    +------------------+-----+-----+-----+

     wc  =  +     32-q-p-5     |  q  |  p  |  5  |

	    +------------------+-----+-----+-----+

   p and q are variable.  For 16-bit Unicode it is sufficient to

   choose p and q such that q+p+5 <= 16.

   The table contains the following uint32_t words:

   - q+p+5,

   - s = upper exclusive bound for wc >> (q+p+5),

   - p+5,

   - 2^q-1,

   - 2^p-1,

   - 1st-level table: s offsets, pointing into the 2nd-level table,

   - 2nd-level table: k*2^q offsets, pointing into the 3rd-level table,

   - 3rd-level table: j*2^p words, each containing 32 bits of data.

*/

static __inline int

__attribute ((always_inline))

wctype_table_lookup (const char *table, uint32_t wc)

{

  uint32_t shift1 = ((const uint32_t *) table)[0];

  uint32_t index1 = wc >> shift1;

  uint32_t bound = ((const uint32_t *) table)[1];

  if (index1 < bound)

    {

      uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];

      if (lookup1 != 0)

	{

	  uint32_t shift2 = ((const uint32_t *) table)[2];

	  uint32_t mask2 = ((const uint32_t *) table)[3];

	  uint32_t index2 = (wc >> shift2) & mask2;

	  uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];

	  if (lookup2 != 0)

	    {

	      uint32_t mask3 = ((const uint32_t *) table)[4];

	      uint32_t index3 = (wc >> 5) & mask3;

	      uint32_t lookup3 = ((const uint32_t *)(table + lookup2))[index3];

	      return (lookup3 >> (wc & 0x1f)) & 1;

	    }

	}

    }

  return 0;

}

/* Byte tables are similar to bit tables, except that the addressing

   unit is a single byte, and no 5 bits are used as a word index.  */

static __inline int

__attribute ((always_inline))

wcwidth_table_lookup (const char *table, uint32_t wc)

{

  uint32_t shift1 = ((const uint32_t *) table)[0];

  uint32_t index1 = wc >> shift1;

  uint32_t bound = ((const uint32_t *) table)[1];

  if (index1 < bound)

    {

      uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];

      if (lookup1 != 0)

	{

	  uint32_t shift2 = ((const uint32_t *) table)[2];

	  uint32_t mask2 = ((const uint32_t *) table)[3];

	  uint32_t index2 = (wc >> shift2) & mask2;

	  uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];

	  if (lookup2 != 0)

	    {

	      uint32_t mask3 = ((const uint32_t *) table)[4];

	      uint32_t index3 = wc & mask3;

	      uint8_t lookup3 = ((const uint8_t *)(table + lookup2))[index3];

	      return lookup3;

	    }

	}

    }

  return 0xff;

}

/* Mapping tables are similar to bit tables, except that the

   addressing unit is a single signed 32-bit word, containing the

   difference between the desired result and the argument, and no 5

   bits are used as a word index.  */

static __inline uint32_t

__attribute ((always_inline))

wctrans_table_lookup (const char *table, uint32_t wc)

{

  uint32_t shift1 = ((const uint32_t *) table)[0];

  uint32_t index1 = wc >> shift1;

  uint32_t bound = ((const uint32_t *) table)[1];

  if (index1 < bound)

    {

      uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];

      if (lookup1 != 0)

	{

	  uint32_t shift2 = ((const uint32_t *) table)[2];

	  uint32_t mask2 = ((const uint32_t *) table)[3];

	  uint32_t index2 = (wc >> shift2) & mask2;

	  uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];

	  if (lookup2 != 0)

	    {

	      uint32_t mask3 = ((const uint32_t *) table)[4];

	      uint32_t index3 = wc & mask3;

	      int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3];

	      return wc + lookup3;

	    }

	}

    }

  return wc;

}