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/*
* jutils.c
*
* Copyright (C) 1991, 1992, 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 miscellaneous utility routines needed for both
* compression and decompression.
* Note we prefix all global names with "j" to minimize conflicts with
* a surrounding application.
*/
#include "jinclude.h"
GLOBAL long
jround_up (long a, long b)
/* Compute a rounded up to next multiple of b; a >= 0, b > 0 */
{
a += b-1;
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, long 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 should not overlap.
* 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 long 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, long 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 = 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_medium 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
}
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