/* Portions Copyright (C) 2001 artofcode LLC.
   Portions Copyright (C) 1996, 2001 Artifex Software Inc.
   Portions Copyright (C) 1988, 2000 Aladdin Enterprises.
   This software is based in part on the work of the Independent JPEG Group.
   All Rights Reserved.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/ or
   contact Artifex Software, Inc., 101 Lucas Valley Road #110,
   San Rafael, CA  94903, (415)492-9861, for further information. */

/*$RCSfile: gsbittab.h,v $ $Revision: 1.9 $ */
/* Interface to tables for bit operations */

#ifndef gsbittab_INCLUDED
#  define gsbittab_INCLUDED

/*
 * Generate tables for transforming 2, 4, 6, or 8 bits.
 */
#define btab2_(v0,v2,v1)\
  v0,v1+v0,v2+v0,v2+v1+v0
#define bit_table_2(v0,v2,v1) btab2_(v0,v2,v1)
#define btab4_(v0,v8,v4,v2,v1)\
  btab2_(v0,v2,v1), btab2_(v4+v0,v2,v1),\
  btab2_(v8+v0,v2,v1), btab2_(v8+v4+v0,v2,v1)
#define bit_table_4(v0,v8,v4,v2,v1) btab4_(v0,v8,v4,v2,v1)
#define btab6_(v0,v20,v10,v8,v4,v2,v1)\
  btab4_(v0,v8,v4,v2,v1), btab4_(v10+v0,v8,v4,v2,v1),\
  btab4_(v20+v0,v8,v4,v2,v1), btab4_(v20+v10+v0,v8,v4,v2,v1)
#define bit_table_6(v0,v20,v10,v8,v4,v2,v1) btab6_(v0,v20,v10,v8,v4,v2,v1)
#define bit_table_8(v0,v80,v40,v20,v10,v8,v4,v2,v1)\
  btab6_(v0,v20,v10,v8,v4,v2,v1), btab6_(v40+v0,v20,v10,v8,v4,v2,v1),\
  btab6_(v80+v0,v20,v10,v8,v4,v2,v1), btab6_(v80+v40+v0,v20,v10,v8,v4,v2,v1)

/*
 * byte_reverse_bits[B] = the byte B with the order of bits reversed.
 */
extern const byte byte_reverse_bits[256];

/*
 * byte_right_mask[N] = a byte with N trailing 1s, 0 <= N <= 8.
 */
extern const byte byte_right_mask[9];

/*
 * byte_count_bits[B] = the number of 1-bits in a byte with value B.
 */
extern const byte byte_count_bits[256];

/*
 * byte_bit_run_length_N[B], for 0 <= N <= 7, gives the length of the
 * run of 1-bits starting at bit N in a byte with value B,
 * numbering the bits in the byte as 01234567.  If the run includes
 * the low-order bit (i.e., might be continued into a following byte),
 * the run length is increased by 8.
 */
extern const byte
    byte_bit_run_length_0[256], byte_bit_run_length_1[256],
    byte_bit_run_length_2[256], byte_bit_run_length_3[256],
    byte_bit_run_length_4[256], byte_bit_run_length_5[256],
    byte_bit_run_length_6[256], byte_bit_run_length_7[256];

/*
 * byte_bit_run_length[N] points to byte_bit_run_length_N.
 * byte_bit_run_length_neg[N] = byte_bit_run_length[-N & 7].
 */
extern const byte *const byte_bit_run_length[8];
extern const byte *const byte_bit_run_length_neg[8];

/*
 * byte_acegbdfh_to_abcdefgh[acegbdfh] = abcdefgh, where the letters
 * denote the individual bits of the byte.
 */
extern const byte byte_acegbdfh_to_abcdefgh[256];

#endif /* gsbittab_INCLUDED */
