mirror of
https://github.com/classilla/tenfourfox.git
synced 2024-11-04 10:05:51 +00:00
133 lines
3.7 KiB
C
133 lines
3.7 KiB
C
/*
|
|
* jutils.c
|
|
*
|
|
* This file was part of the Independent JPEG Group's software:
|
|
* Copyright (C) 1991-1996, Thomas G. Lane.
|
|
* It was modified by The libjpeg-turbo Project to include only code
|
|
* relevant to libjpeg-turbo.
|
|
* 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).
|
|
*/
|
|
|
|
#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);
|
|
}
|
|
|
|
|
|
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;
|
|
register size_t count = (size_t) (num_cols * sizeof(JSAMPLE));
|
|
register int row;
|
|
|
|
input_array += source_row;
|
|
output_array += dest_row;
|
|
|
|
for (row = num_rows; row > 0; row--) {
|
|
inptr = *input_array++;
|
|
outptr = *output_array++;
|
|
MEMCOPY(outptr, inptr, count);
|
|
}
|
|
}
|
|
|
|
|
|
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. */
|
|
{
|
|
MEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * sizeof(JCOEF)));
|
|
}
|
|
|
|
|
|
GLOBAL(void)
|
|
jzero_far (void * target, size_t bytestozero)
|
|
/* Zero out a chunk of memory. */
|
|
/* This might be sample-array data, block-array data, or alloc_large data. */
|
|
{
|
|
MEMZERO(target, bytestozero);
|
|
}
|