/* 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.c */
/* 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)
#if arch_is_big_endian
const bits32 lookup4x1to32_identity[16] =
   {	map4tox(0L, 0xffL, 0xff00L, 0xff0000L, 0xff000000L)	};
const bits32 lookup4x1to32_inverted[16] =
   {	map4tox(0xffffffffL, 0xffL, 0xff00L, 0xff0000L, 0xff000000L)	};
#else					/* !arch_is_big_endian */
const bits32 lookup4x1to32_identity[16] =
   {	map4tox(0L, 0xff000000L, 0xff0000L, 0xff00L, 0xffL)	};
const bits32 lookup4x1to32_inverted[16] =
   {	map4tox(0xffffffffL, 0xff000000L, 0xff0000L, 0xff00L, 0xffL)	};
#endif

/* ---------------- 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;
}
