doom3-bfg/neo/renderer/jpeg-6/jutils.cpp

/*
 * jutils.c
 *
 * Copyright (C) 1991-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains tables and miscellaneous utility routines needed
 * for both compression and decompression.
 * Note we prefix all global names with "j" to minimize conflicts with
 * a surrounding application.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "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).
 */

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
};

/*
 * 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.
 */
    register JSAMPROW inptr, outptr;
#ifdef FMEMCOPY
    register size_t count = (size_t) ( num_cols * SIZEOF( JSAMPLE ) );
#else
    register JDIMENSION count;
#endif
    register 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
    register JCOEFPTR inptr, outptr;
    register 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
    register char FAR * ptr = (char FAR *) target;
    register size_t count;

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