3rdparty/libjpeg/jutils.c

/*
 * jutils.c
 *
 * Copyright (C) 1991-1996, 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).
 */

#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.
 */
{
  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
}
1	/*
2	* jutils.c
3	*
4	* Copyright (C) 1991-1996, Thomas G. Lane.
5	* This file is part of the Independent JPEG Group's software.
6	* For conditions of distribution and use, see the accompanying README file.
7	*
8	* This file contains tables and miscellaneous utility routines needed
9	* for both compression and decompression.
10	* Note we prefix all global names with "j" to minimize conflicts with
11	* a surrounding application.
12	*/
13
14	#define JPEG_INTERNALS
15	#include "jinclude.h"
16	#include "jpeglib.h"
17
18
19	/*
20	* jpeg_zigzag_order[i] is the zigzag-order position of the i'th element
21	* of a DCT block read in natural order (left to right, top to bottom).
22	*/
23
24	#if 0 /* This table is not actually needed in v6a */
25
26	const int jpeg_zigzag_order[DCTSIZE2] = {
27	0, 1, 5, 6, 14, 15, 27, 28,
28	2, 4, 7, 13, 16, 26, 29, 42,
29	3, 8, 12, 17, 25, 30, 41, 43,
30	9, 11, 18, 24, 31, 40, 44, 53,
31	10, 19, 23, 32, 39, 45, 52, 54,
32	20, 22, 33, 38, 46, 51, 55, 60,
33	21, 34, 37, 47, 50, 56, 59, 61,
34	35, 36, 48, 49, 57, 58, 62, 63
35	};
36
37	#endif
38
39	/*
40	* jpeg_natural_order[i] is the natural-order position of the i'th element
41	* of zigzag order.
42	*
43	* When reading corrupted data, the Huffman decoders could attempt
44	* to reference an entry beyond the end of this array (if the decoded
45	* zero run length reaches past the end of the block). To prevent
46	* wild stores without adding an inner-loop test, we put some extra
47	* "63"s after the real entries. This will cause the extra coefficient
48	* to be stored in location 63 of the block, not somewhere random.
49	* The worst case would be a run-length of 15, which means we need 16
50	* fake entries.
51	*/
52
53	const int jpeg_natural_order[DCTSIZE2+16] = {
54	0, 1, 8, 16, 9, 2, 3, 10,
55	17, 24, 32, 25, 18, 11, 4, 5,
56	12, 19, 26, 33, 40, 48, 41, 34,
57	27, 20, 13, 6, 7, 14, 21, 28,
58	35, 42, 49, 56, 57, 50, 43, 36,
59	29, 22, 15, 23, 30, 37, 44, 51,
60	58, 59, 52, 45, 38, 31, 39, 46,
61	53, 60, 61, 54, 47, 55, 62, 63,
62	63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
63	63, 63, 63, 63, 63, 63, 63, 63
64	};
65
66
67	/*
68	* Arithmetic utilities
69	*/
70
71	GLOBAL(long)
72	jdiv_round_up (long a, long b)
73	/* Compute a/b rounded up to next integer, ie, ceil(a/b) */
74	/* Assumes a >= 0, b > 0 */
75	{
76	return (a + b - 1L) / b;
77	}
78
79
80	GLOBAL(long)
81	jround_up (long a, long b)
82	/* Compute a rounded up to next multiple of b, ie, ceil(a/b)b /
83	/* Assumes a >= 0, b > 0 */
84	{
85	a += b - 1L;
86	return a - (a % b);
87	}
88
89
90	/* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays
91	* and coefficient-block arrays. This won't work on 80x86 because the arrays
92	* are FAR and we're assuming a small-pointer memory model. However, some
93	* DOS compilers provide far-pointer versions of memcpy() and memset() even
94	* in the small-model libraries. These will be used if USE_FMEM is defined.
95	* Otherwise, the routines below do it the hard way. (The performance cost
96	* is not all that great, because these routines aren't very heavily used.)
97	*/
98
99	#ifndef NEED_FAR_POINTERS /* normal case, same as regular macros */
100	#define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size)
101	#define FMEMZERO(target,size) MEMZERO(target,size)
102	#else /* 80x86 case, define if we can */
103	#ifdef USE_FMEM
104	#define FMEMCOPY(dest,src,size) _fmemcpy((void FAR )(dest), (const void FAR )(src), (size_t)(size))
105	#define FMEMZERO(target,size) _fmemset((void FAR *)(target), 0, (size_t)(size))
106	#endif
107	#endif
108
109
110	GLOBAL(void)
111	jcopy_sample_rows (JSAMPARRAY input_array, int source_row,
112	JSAMPARRAY output_array, int dest_row,
113	int num_rows, JDIMENSION num_cols)
114	/* Copy some rows of samples from one place to another.
115	* num_rows rows are copied from input_array[source_row++]
116	* to output_array[dest_row++]; these areas may overlap for duplication.
117	* The source and destination arrays must be at least as wide as num_cols.
118	*/
119	{
120	register JSAMPROW inptr, outptr;
121	#ifdef FMEMCOPY
122	register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE));
123	#else
124	register JDIMENSION count;
125	#endif
126	register int row;
127
128	input_array += source_row;
129	output_array += dest_row;
130
131	for (row = num_rows; row > 0; row--) {
132	inptr = *input_array++;
133	outptr = *output_array++;
134	#ifdef FMEMCOPY
135	FMEMCOPY(outptr, inptr, count);
136	#else
137	for (count = num_cols; count > 0; count--)
138	outptr++ = inptr++; /* needn't bother with GETJSAMPLE() here */
139	#endif
140	}
141	}
142
143
144	GLOBAL(void)
145	jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row,
146	JDIMENSION num_blocks)
147	/* Copy a row of coefficient blocks from one place to another. */
148	{
149	#ifdef FMEMCOPY
150	FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
151	#else
152	register JCOEFPTR inptr, outptr;
153	register long count;
154
155	inptr = (JCOEFPTR) input_row;
156	outptr = (JCOEFPTR) output_row;
157	for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) {
158	outptr++ = inptr++;
159	}
160	#endif
161	}
162
163
164	GLOBAL(void)
165	jzero_far (void FAR * target, size_t bytestozero)
166	/* Zero out a chunk of FAR memory. */
167	/* This might be sample-array data, block-array data, or alloc_large data. */
168	{
169	#ifdef FMEMZERO
170	FMEMZERO(target, bytestozero);
171	#else
172	register char FAR * ptr = (char FAR *) target;
173	register size_t count;
174
175	for (count = bytestozero; count > 0; count--) {
176	*ptr++ = 0;
177	}
178	#endif
179	}