/* Copyright (C) 1997, 1999 artofcode LLC.  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 as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  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.

*/

/*$Id: gxsample.h,v 1.2.6.1.2.1 2003/01/17 00:49:04 giles Exp $ */
/* Sample lookup and expansion */

#ifndef gxsample_INCLUDED
#  define gxsample_INCLUDED

/*
 * The following union implements the expansion of sample
 * values from N bits to 8, and a possible linear transformation.
 */
typedef union sample_lookup_s {
    bits32 lookup4x1to32[16];	/* 1 bit/sample, not spreading */
    bits16 lookup2x2to16[16];	/* 2 bits/sample, not spreading */
    byte lookup8[256];		/* 1 bit/sample, spreading [2] */
    /* 2 bits/sample, spreading [4] */
    /* 4 bits/sample [16] */
    /* 8 bits/sample [256] */
} sample_lookup_t;

/*
 * Define identity and inverted expansion lookups for 1-bit input values.
 * These can be cast to a const sample_lookup_t.
 */
extern const bits32 lookup4x1to32_identity[16];
extern const bits32 lookup4x1to32_inverted[16];

/*
 * Define procedures to unpack and shuffle image data samples.  The Unix C
 * compiler can't handle typedefs for procedure (as opposed to
 * pointer-to-procedure) types, so we have to do it with macros instead.
 *
 * The original data start at sample data_x relative to data.
 * bptr points to the buffer normally used to deliver the unpacked data.
 * The unpacked data are at sample *pdata_x relative to the return value.
 *
 * Note that this procedure may return either a pointer to the buffer, or
 * a pointer to the original data.
 */
#define SAMPLE_UNPACK_PROC(proc)\
  const byte *proc(P7(byte *bptr, int *pdata_x, const byte *data, int data_x,\
		      uint dsize, const sample_lookup_t *ptab, int spread))
typedef SAMPLE_UNPACK_PROC((*sample_unpack_proc_t));

/*
 * Declare the 1-for-1 unpacking procedure.
 */
SAMPLE_UNPACK_PROC(sample_unpack_copy);
/*
 * Declare unpacking procedures for 1, 2, 4, and 8 bits per pixel,
 * with optional spreading of the result.
 */
SAMPLE_UNPACK_PROC(sample_unpack_1);
SAMPLE_UNPACK_PROC(sample_unpack_2);
SAMPLE_UNPACK_PROC(sample_unpack_4);
SAMPLE_UNPACK_PROC(sample_unpack_8);

#endif /* gxsample_INCLUDED */