/* Copyright (C) 1997, 1998 Aladdin Enterprises.  All rights reserved.
  
  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License version 2
  as published by the Free Software Foundation.


  This software is provided AS-IS with no warranty, either express or
  implied. That is, this program 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
  General Public License for more details

  You should have received a copy of the GNU General Public License along
  with this program; if not, write to the Free Software Foundation, Inc.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.
  
  For more information about licensing, please refer to
  http://www.ghostscript.com/licensing/. For information on
  commercial licensing, go to http://www.artifex.com/licensing/ or
  contact Artifex Software, Inc., 101 Lucas Valley Road #110,
  San Rafael, CA  94903, U.S.A., +1(415)492-9861.
*/

/* $Id: gxbitops.h,v 1.4 2002/02/21 22:24:52 giles Exp $ */
/* Internal definitions for bitmap operations */

#ifndef gxbitops_INCLUDED
#  define gxbitops_INCLUDED

#include "gsbitops.h"

/*
 * Macros for processing bitmaps in the largest possible chunks.
 * Bits within a byte are always stored big-endian;
 * bytes are likewise stored in left-to-right order, i.e., big-endian.
 * Note that this is the format used for the source of copy_mono.
 * It used to be the case that bytes were stored in the natural
 * platform order, and the client had force them into big-endian order
 * by calling gdev_mem_ensure_byte_order, but this no longer necessary.
 *
 * Note that we use type uint for register variables holding a chunk:
 * for this reason, the chunk size cannot be larger than uint.
 */
/* Generic macros for chunk accessing. */
#define cbytes(ct) size_of(ct)	/* sizeof may be unsigned */
#  define chunk_bytes cbytes(chunk)
/* The clog2_bytes macro assumes that ints are 2, 4, or 8 bytes in size. */
#define clog2_bytes(ct) (size_of(ct) == 8 ? 3 : size_of(ct)>>1)
#  define chunk_log2_bytes clog2_bytes(chunk)
#define cbits(ct) (size_of(ct)*8)	/* sizeof may be unsigned */
#  define chunk_bits cbits(chunk)
#define clog2_bits(ct) (clog2_bytes(ct)+3)
#  define chunk_log2_bits clog2_bits(chunk)
#define cbit_mask(ct) (cbits(ct)-1)
#  define chunk_bit_mask cbit_mask(chunk)
#define calign_bytes(ct)\
  (sizeof(ct) == 1 ? 1:\
   sizeof(ct) == sizeof(short) ? arch_align_short_mod :\
   sizeof(ct) == sizeof(int) ? arch_align_int_mod : arch_align_long_mod)
#  define chunk_align_bytes calign_bytes(chunk)
#define calign_bit_mask(ct) (calign_bytes(ct)*8-1)
#  define chunk_align_bit_mask calign_bit_mask(chunk)
/*
 * The obvious definition for cmask is:
 *      #define cmask(ct) ((ct)~(ct)0)
 * but this doesn't work on the VAX/VMS compiler, which fails to truncate
 * the value to 16 bits when ct is ushort.
 * Instead, we have to generate the mask with no extra 1-bits.
 * We can't do this in the obvious way:
 *      #define cmask(ct) ((1 << (size_of(ct) * 8)) - 1)
 * because some compilers won't allow a shift of the full type size.
 * Instead, we have to do something really awkward:
 */
#define cmask(ct) ((ct) (((((ct)1 << (size_of(ct)*8-2)) - 1) << 2) + 3))
#  define chunk_all_bits cmask(chunk)
/*
 * The obvious definition for chi_bits is:
 *      #define chi_bits(ct,n) (cmask(ct)-(cmask(ct)>>(n)))
 * but this doesn't work on the DEC/MIPS compilers.
 * Instead, we have to restrict chi_bits to only working for values of n
 * between 0 and cbits(ct)-1, and use
 */
#define chi_bits(ct,n) (ct)(~(ct)1 << (cbits(ct)-1 - (n)))
#  define chunk_hi_bits(n) chi_bits(chunk,n)

/* Define whether this is a machine where chunks are long, */
/* but the machine can't shift a long by its full width. */
#define arch_cant_shift_full_chunk\
  (arch_is_big_endian && !arch_ints_are_short && !arch_can_shift_full_long)

/* Pointer arithmetic macros. */
#define inc_ptr(ptr,delta)\
	(ptr = (void *)((byte *)ptr + (delta)))

/* Define macros for setting up left- and right-end masks. */
/* These are used for monobit operations, and for filling */
/* with 2- and 4-bit-per-pixel patterns. */

/*
 * Define the chunk size for monobit copying operations.
 */
#if arch_is_big_endian
#  define mono_copy_chunk uint
#  define set_mono_right_mask(var, w)\
	(var = ((w) == chunk_bits ? chunk_all_bits : chunk_hi_bits(w)))
/*
 * We have to split the following statement because of a bug in the Xenix C
 * compiler (it produces a signed rather than an unsigned shift if we don't
 * split).
 */
#  define set_mono_thin_mask(var, w, bit)\
	set_mono_right_mask(var, w), var >>= (bit)
/*
 * We have to split the following statement in two because of a bug
 * in the DEC VAX/VMS C compiler.
 */
#  define set_mono_left_mask(var, bit)\
	(var = chunk_all_bits, var >>= (bit))
#else
#  define mono_copy_chunk bits16
extern const bits16 mono_copy_masks[17];

#  if mono_fill_chunk_bytes == 2
#    define mono_fill_masks mono_copy_masks
#  else
extern const bits32 mono_fill_masks[33];

#  endif
/*
 * We define mono_masks as either mono_fill_masks or
 * mono_copy_masks before using the following macros.
 */
#  define set_mono_left_mask(var, bit)\
	(var = mono_masks[bit])
#  define set_mono_thin_mask(var, w, bit)\
	(var = ~mono_masks[(w) + (bit)] & mono_masks[bit])
#  define set_mono_right_mask(var, ebit)\
	(var = ~mono_masks[ebit])
#endif

#endif /* gxbitops_INCLUDED */
