/* Copyright (C) 1997, 1999 Aladdin Enterprises.  All rights reserved.
  
  This file is part of GNU Ghostscript.
  
  GNU Ghostscript is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
  to anyone for the consequences of using it or for whether it serves any
  particular purpose or works at all, unless he says so in writing.  Refer
  to the GNU General Public License for full details.
  
  Everyone is granted permission to copy, modify and redistribute GNU
  Ghostscript, but only under the conditions described in the GNU General
  Public License.  A copy of this license is supposed to have been given
  to you along with GNU Ghostscript so you can know your rights and
  responsibilities.  It should be in a file named COPYING.  Among other
  things, the copyright notice and this notice must be preserved on all
  copies.
*/

/*$RCSfile: gxsample.c,v $ $Revision: 1.2.2.1 $ */
/* Sample unpacking procedures */
#include "gx.h"
#include "gxsample.h"

/* ---------------- Lookup tables ---------------- */

/*
 * Define standard tables for spreading 1-bit input data.
 * Note that these depend on the end-orientation of the CPU.
 * We can't simply define them as byte arrays, because
 * they might not wind up properly long- or short-aligned.
 */
#define map4tox(z,a,b,c,d)\
    z, z^a, z^b, z^(a+b),\
    z^c, z^(a+c), z^(b+c), z^(a+b+c),\
    z^d, z^(a+d), z^(b+d), z^(a+b+d),\
    z^(c+d), z^(a+c+d), z^(b+c+d), z^(a+b+c+d)
/* Work around warnings from really picky compilers. */
#ifdef __STDC__
#  define n0L 0xffffffffU
#  define ffL8 0x0000ff00U
#  define ffL16 0x00ff0000U
#  define ffL24 0xff000000U
#else
#if arch_sizeof_long == 4
/*
 * The compiler evaluates long expressions mod 2^32.  Even very picky
 * compilers allow assigning signed longs to unsigned longs, so we use
 * signed constants.
 */
#  define n0L (-1)
#  define ffL8 0x0000ff00
#  define ffL16 0x00ff0000
#  define ffL24 (-0x01000000)
#else
/*
 * The compiler evaluates long expressions mod 2^64.
 */
#  define n0L 0xffffffffL
#  define ffL8 0x0000ff00L
#  define ffL16 0x00ff0000L
#  define ffL24 0xff000000L
#endif
#endif
#if arch_is_big_endian
const bits32 lookup4x1to32_identity[16] = {
    map4tox(0, 0xff, ffL8, ffL16, ffL24)
};
const bits32 lookup4x1to32_inverted[16] = {
    map4tox(n0L, 0xff, ffL8, ffL16, ffL24)
};
#else /* !arch_is_big_endian */
const bits32 lookup4x1to32_identity[16] = {
    map4tox(0, ffL24, ffL16, ffL8, 0xff)
};
const bits32 lookup4x1to32_inverted[16] = {
    map4tox(n0L, ffL24, ffL16, ffL8, 0xff)
};
#endif
#undef n0L
#undef ffL8
#undef ffL16
#undef ffL24

/* ---------------- Unpacking procedures ---------------- */

const byte *
sample_unpack_copy(byte * bptr, int *pdata_x, const byte * data, int data_x,
		uint dsize, const sample_lookup_t * ignore_ptab, int spread)
{				/* We're going to use the data right away, so no copying is needed. */
    *pdata_x = data_x;
    return data;
}

const byte *
sample_unpack_1(byte * bptr, int *pdata_x, const byte * data, int data_x,
		uint dsize, const sample_lookup_t * ptab, int spread)
{
    const byte *psrc = data + (data_x >> 3);
    int left = dsize - (data_x >> 3);

    if (spread == 1) {
	bits32 *bufp = (bits32 *) bptr;
	const bits32 *map = &ptab->lookup4x1to32[0];
	uint b;

	if (left & 1) {
	    b = psrc[0];
	    bufp[0] = map[b >> 4];
	    bufp[1] = map[b & 0xf];
	    psrc++, bufp += 2;
	}
	left >>= 1;
	while (left--) {
	    b = psrc[0];
	    bufp[0] = map[b >> 4];
	    bufp[1] = map[b & 0xf];
	    b = psrc[1];
	    bufp[2] = map[b >> 4];
	    bufp[3] = map[b & 0xf];
	    psrc += 2, bufp += 4;
	}
    } else {
	byte *bufp = bptr;
	const byte *map = &ptab->lookup8[0];

	while (left--) {
	    uint b = *psrc++;

	    *bufp = map[b >> 7];
	    bufp += spread;
	    *bufp = map[(b >> 6) & 1];
	    bufp += spread;
	    *bufp = map[(b >> 5) & 1];
	    bufp += spread;
	    *bufp = map[(b >> 4) & 1];
	    bufp += spread;
	    *bufp = map[(b >> 3) & 1];
	    bufp += spread;
	    *bufp = map[(b >> 2) & 1];
	    bufp += spread;
	    *bufp = map[(b >> 1) & 1];
	    bufp += spread;
	    *bufp = map[b & 1];
	    bufp += spread;
	}
    }
    *pdata_x = data_x & 7;
    return bptr;
}

const byte *
sample_unpack_2(byte * bptr, int *pdata_x, const byte * data, int data_x,
		uint dsize, const sample_lookup_t * ptab, int spread)
{
    const byte *psrc = data + (data_x >> 2);
    int left = dsize - (data_x >> 2);

    if (spread == 1) {
	bits16 *bufp = (bits16 *) bptr;
	const bits16 *map = &ptab->lookup2x2to16[0];

	while (left--) {
	    uint b = *psrc++;

	    *bufp++ = map[b >> 4];
	    *bufp++ = map[b & 0xf];
	}
    } else {
	byte *bufp = bptr;
	const byte *map = &ptab->lookup8[0];

	while (left--) {
	    unsigned b = *psrc++;

	    *bufp = map[b >> 6];
	    bufp += spread;
	    *bufp = map[(b >> 4) & 3];
	    bufp += spread;
	    *bufp = map[(b >> 2) & 3];
	    bufp += spread;
	    *bufp = map[b & 3];
	    bufp += spread;
	}
    }
    *pdata_x = data_x & 3;
    return bptr;
}

const byte *
sample_unpack_4(byte * bptr, int *pdata_x, const byte * data, int data_x,
		uint dsize, const sample_lookup_t * ptab, int spread)
{
    byte *bufp = bptr;
    const byte *psrc = data + (data_x >> 1);
    int left = dsize - (data_x >> 1);
    const byte *map = &ptab->lookup8[0];

    while (left--) {
	uint b = *psrc++;

	*bufp = map[b >> 4];
	bufp += spread;
	*bufp = map[b & 0xf];
	bufp += spread;
    }
    *pdata_x = data_x & 1;
    return bptr;
}

const byte *
sample_unpack_8(byte * bptr, int *pdata_x, const byte * data, int data_x,
		uint dsize, const sample_lookup_t * ptab, int spread)
{
    byte *bufp = bptr;
    const byte *psrc = data + data_x;

    *pdata_x = 0;
    if (spread == 1) {
	if (ptab->lookup8[0] != 0 ||
	    ptab->lookup8[255] != 255
	    ) {
	    uint left = dsize - data_x;
	    const byte *map = &ptab->lookup8[0];

	    while (left--)
		*bufp++ = map[*psrc++];
	} else {		/* No copying needed, and we'll use the data right away. */
	    return psrc;
	}
    } else {
	int left = dsize - data_x;
	const byte *map = &ptab->lookup8[0];

	for (; left--; psrc++, bufp += spread)
	    *bufp = map[*psrc];
    }
    return bptr;
}
