jutils.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "mrpt_jpeglib.h"

/*
 * jpeg_zigzag_order[i] is the zigzag-order position of the i'th element
 * of a DCT block read in natural order (left to right, top to bottom).
 */

#if 0 /* This table is not actually needed in v6a */

const int jpeg_zigzag_order[DCTSIZE2] = {
   0,  1,  5,  6, 14, 15, 27, 28,
   2,  4,  7, 13, 16, 26, 29, 42,
   3,  8, 12, 17, 25, 30, 41, 43,
   9, 11, 18, 24, 31, 40, 44, 53,
  10, 19, 23, 32, 39, 45, 52, 54,
  20, 22, 33, 38, 46, 51, 55, 60,
  21, 34, 37, 47, 50, 56, 59, 61,
  35, 36, 48, 49, 57, 58, 62, 63
};

#endif

/*
 * jpeg_natural_order[i] is the natural-order position of the i'th element
 * of zigzag order.
 *
 * When reading corrupted data, the Huffman decoders could attempt
 * to reference an entry beyond the end of this array (if the decoded
 * zero run length reaches past the end of the block).  To prevent
 * wild stores without adding an inner-loop test, we put some extra
 * "63"s after the real entries.  This will cause the extra coefficient
 * to be stored in location 63 of the block, not somewhere random.
 * The worst case would be a run-length of 15, which means we need 16
 * fake entries.
 */

const int jpeg_natural_order[DCTSIZE2 + 16] =
        {
                0,  1,  8,  16, 9,  2,  3,  10, 17, 24, 32, 25, 18, 11, 4,
                5,  12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13, 6,  7,  14,
                21, 28, 35, 42, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30,
                37, 44, 51, 58, 59, 52, 45, 38, 31, 39, 46, 53, 60, 61, 54,
                47, 55, 62, 63, 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for
                                                                                                                   safety in decoder */
                63, 63, 63, 63, 63, 63, 63, 63};

/*
 * Arithmetic utilities
 */

GLOBAL(long)
jdiv_round_up(long a, long b)
/* Compute a/b rounded up to next integer, ie, ceil(a/b) */
/* Assumes a >= 0, b > 0 */ { return (a + b - 1L) / b; }
GLOBAL(long)
jround_up(long a, long b)
/* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
/* Assumes a >= 0, b > 0 */
{
        a += b - 1L;
        return a - (a % b);
}

/* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays
 * and coefficient-block arrays.  This won't work on 80x86 because the arrays
 * are FAR and we're assuming a small-pointer memory model.  However, some
 * DOS compilers provide far-pointer versions of memcpy() and memset() even
 * in the small-model libraries.  These will be used if USE_FMEM is defined.
 * Otherwise, the routines below do it the hard way.  (The performance cost
 * is not all that great, because these routines aren't very heavily used.)
 */

#ifndef NEED_FAR_POINTERS /* normal case, same as regular macros */
#define FMEMCOPY(dest, src, size) MEMCOPY(dest, src, size)
#define FMEMZERO(target, size) MEMZERO(target, size)
#else /* 80x86 case, define if we can */
#ifdef USE_FMEM
#define FMEMCOPY(dest, src, size) \
        _fmemcpy((void FAR*)(dest), (const void FAR*)(src), (size_t)(size))
#define FMEMZERO(target, size) _fmemset((void FAR*)(target), 0, (size_t)(size))
#endif
#endif

GLOBAL(void)
jcopy_sample_rows(
        JSAMPARRAY input_array, int source_row, JSAMPARRAY output_array,
        int dest_row, int num_rows, JDIMENSION num_cols)
/* Copy some rows of samples from one place to another.
 * num_rows rows are copied from input_array[source_row++]
 * to output_array[dest_row++]; these areas may overlap for duplication.
 * The source and destination arrays must be at least as wide as num_cols.
 */
{
        JSAMPROW inptr, outptr;
#ifdef FMEMCOPY
        size_t count = (size_t)(num_cols * SIZEOF(JSAMPLE));
#else
        JDIMENSION count;
#endif
        int row;

        input_array += source_row;
        output_array += dest_row;

        for (row = num_rows; row > 0; row--)
        {
                inptr = *input_array++;
                outptr = *output_array++;
#ifdef FMEMCOPY
                FMEMCOPY(outptr, inptr, count);
#else
                for (count = num_cols; count > 0; count--)
                        *outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */
#endif
        }
}

GLOBAL(void)
jcopy_block_row(
        JBLOCKROW input_row, JBLOCKROW output_row, JDIMENSION num_blocks)
/* Copy a row of coefficient blocks from one place to another. */
{
#ifdef FMEMCOPY
        FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
#else
        JCOEFPTR inptr, outptr;
        long count;

        inptr = (JCOEFPTR)input_row;
        outptr = (JCOEFPTR)output_row;
        for (count = (long)num_blocks * DCTSIZE2; count > 0; count--)
        {
                *outptr++ = *inptr++;
        }
#endif
}

GLOBAL(void)
jzero_far(void FAR* target, size_t bytestozero)
/* Zero out a chunk of FAR memory. */
/* This might be sample-array data, block-array data, or alloc_large data. */
{
#ifdef FMEMZERO
        FMEMZERO(target, bytestozero);
#else
        char FAR* ptr = (char FAR*)target;
        size_t count;

        for (count = bytestozero; count > 0; count--)
        {
                *ptr++ = 0;
        }
#endif
}