/* Copyright (C) 1997 Aladdin Enterprises.  All rights reserved.
  
  This file is part of Aladdin Ghostscript.
  
  Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
  or distributor accepts any responsibility for the consequences of using it,
  or for whether it serves any particular purpose or works at all, unless he
  or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
  License (the "License") for full details.
  
  Every copy of Aladdin Ghostscript must include a copy of the License,
  normally in a plain ASCII text file named PUBLIC.  The License grants you
  the right to copy, modify and redistribute Aladdin Ghostscript, but only
  under certain conditions described in the License.  Among other things, the
  License requires that the copyright notice and this notice be preserved on
  all copies.
*/

/* gxsample.h */
/* Sample lookup and expansion */

/*
 * 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];
#define sample_lookup_1_identity\
  ((const sample_lookup_t *)lookup4x1to32_identity)
extern const bits32 lookup4x1to32_inverted[16];
#define sample_lookup_1_inverted\
  ((const sample_lookup_t *)lookup4x1to32_inverted)

/*
 * 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))
/*
 * 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);
