1/*
2 * jutils.c
3 *
4 * Copyright (C) 1991-1996, Thomas G. Lane.
5 * Modified 2009 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains tables and miscellaneous utility routines needed
10 * for both compression and decompression.
11 * Note we prefix all global names with "j" to minimize conflicts with
12 * a surrounding application.
13 */
14
15#define JPEG_INTERNALS
16#include "jinclude.h"
17#include "jpeglib.h"
18
19
20/*
21 * jpeg_zigzag_order[i] is the zigzag-order position of the i'th element
22 * of a DCT block read in natural order (left to right, top to bottom).
23 */
24
25#if 0				/* This table is not actually needed in v6a */
26
27const int jpeg_zigzag_order[DCTSIZE2] = {
28   0,  1,  5,  6, 14, 15, 27, 28,
29   2,  4,  7, 13, 16, 26, 29, 42,
30   3,  8, 12, 17, 25, 30, 41, 43,
31   9, 11, 18, 24, 31, 40, 44, 53,
32  10, 19, 23, 32, 39, 45, 52, 54,
33  20, 22, 33, 38, 46, 51, 55, 60,
34  21, 34, 37, 47, 50, 56, 59, 61,
35  35, 36, 48, 49, 57, 58, 62, 63
36};
37
38#endif
39
40/*
41 * jpeg_natural_order[i] is the natural-order position of the i'th element
42 * of zigzag order.
43 *
44 * When reading corrupted data, the Huffman decoders could attempt
45 * to reference an entry beyond the end of this array (if the decoded
46 * zero run length reaches past the end of the block).  To prevent
47 * wild stores without adding an inner-loop test, we put some extra
48 * "63"s after the real entries.  This will cause the extra coefficient
49 * to be stored in location 63 of the block, not somewhere random.
50 * The worst case would be a run-length of 15, which means we need 16
51 * fake entries.
52 */
53
54const int jpeg_natural_order[DCTSIZE2+16] = {
55  0,  1,  8, 16,  9,  2,  3, 10,
56 17, 24, 32, 25, 18, 11,  4,  5,
57 12, 19, 26, 33, 40, 48, 41, 34,
58 27, 20, 13,  6,  7, 14, 21, 28,
59 35, 42, 49, 56, 57, 50, 43, 36,
60 29, 22, 15, 23, 30, 37, 44, 51,
61 58, 59, 52, 45, 38, 31, 39, 46,
62 53, 60, 61, 54, 47, 55, 62, 63,
63 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
64 63, 63, 63, 63, 63, 63, 63, 63
65};
66
67const int jpeg_natural_order7[7*7+16] = {
68  0,  1,  8, 16,  9,  2,  3, 10,
69 17, 24, 32, 25, 18, 11,  4,  5,
70 12, 19, 26, 33, 40, 48, 41, 34,
71 27, 20, 13,  6, 14, 21, 28, 35,
72 42, 49, 50, 43, 36, 29, 22, 30,
73 37, 44, 51, 52, 45, 38, 46, 53,
74 54,
75 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
76 63, 63, 63, 63, 63, 63, 63, 63
77};
78
79const int jpeg_natural_order6[6*6+16] = {
80  0,  1,  8, 16,  9,  2,  3, 10,
81 17, 24, 32, 25, 18, 11,  4,  5,
82 12, 19, 26, 33, 40, 41, 34, 27,
83 20, 13, 21, 28, 35, 42, 43, 36,
84 29, 37, 44, 45,
85 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
86 63, 63, 63, 63, 63, 63, 63, 63
87};
88
89const int jpeg_natural_order5[5*5+16] = {
90  0,  1,  8, 16,  9,  2,  3, 10,
91 17, 24, 32, 25, 18, 11,  4, 12,
92 19, 26, 33, 34, 27, 20, 28, 35,
93 36,
94 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
95 63, 63, 63, 63, 63, 63, 63, 63
96};
97
98const int jpeg_natural_order4[4*4+16] = {
99  0,  1,  8, 16,  9,  2,  3, 10,
100 17, 24, 25, 18, 11, 19, 26, 27,
101 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
102 63, 63, 63, 63, 63, 63, 63, 63
103};
104
105const int jpeg_natural_order3[3*3+16] = {
106  0,  1,  8, 16,  9,  2, 10, 17,
107 18,
108 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
109 63, 63, 63, 63, 63, 63, 63, 63
110};
111
112const int jpeg_natural_order2[2*2+16] = {
113  0,  1,  8,  9,
114 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
115 63, 63, 63, 63, 63, 63, 63, 63
116};
117
118
119/*
120 * Arithmetic utilities
121 */
122
123GLOBAL(long)
124jdiv_round_up (long a, long b)
125/* Compute a/b rounded up to next integer, ie, ceil(a/b) */
126/* Assumes a >= 0, b > 0 */
127{
128  return (a + b - 1L) / b;
129}
130
131
132GLOBAL(long)
133jround_up (long a, long b)
134/* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
135/* Assumes a >= 0, b > 0 */
136{
137  a += b - 1L;
138  return a - (a % b);
139}
140
141
142/* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays
143 * and coefficient-block arrays.  This won't work on 80x86 because the arrays
144 * are FAR and we're assuming a small-pointer memory model.  However, some
145 * DOS compilers provide far-pointer versions of memcpy() and memset() even
146 * in the small-model libraries.  These will be used if USE_FMEM is defined.
147 * Otherwise, the routines below do it the hard way.  (The performance cost
148 * is not all that great, because these routines aren't very heavily used.)
149 */
150
151#ifndef NEED_FAR_POINTERS	/* normal case, same as regular macros */
152#define FMEMCOPY(dest,src,size)	MEMCOPY(dest,src,size)
153#define FMEMZERO(target,size)	MEMZERO(target,size)
154#else				/* 80x86 case, define if we can */
155#ifdef USE_FMEM
156#define FMEMCOPY(dest,src,size)	_fmemcpy((void FAR *)(dest), (const void FAR *)(src), (size_t)(size))
157#define FMEMZERO(target,size)	_fmemset((void FAR *)(target), 0, (size_t)(size))
158#endif
159#endif
160
161
162GLOBAL(void)
163jcopy_sample_rows (JSAMPARRAY input_array, int source_row,
164		   JSAMPARRAY output_array, int dest_row,
165		   int num_rows, JDIMENSION num_cols)
166/* Copy some rows of samples from one place to another.
167 * num_rows rows are copied from input_array[source_row++]
168 * to output_array[dest_row++]; these areas may overlap for duplication.
169 * The source and destination arrays must be at least as wide as num_cols.
170 */
171{
172  register JSAMPROW inptr, outptr;
173#ifdef FMEMCOPY
174  register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE));
175#else
176  register JDIMENSION count;
177#endif
178  register int row;
179
180  input_array += source_row;
181  output_array += dest_row;
182
183  for (row = num_rows; row > 0; row--) {
184    inptr = *input_array++;
185    outptr = *output_array++;
186#ifdef FMEMCOPY
187    FMEMCOPY(outptr, inptr, count);
188#else
189    for (count = num_cols; count > 0; count--)
190      *outptr++ = *inptr++;	/* needn't bother with GETJSAMPLE() here */
191#endif
192  }
193}
194
195
196GLOBAL(void)
197jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row,
198		 JDIMENSION num_blocks)
199/* Copy a row of coefficient blocks from one place to another. */
200{
201#ifdef FMEMCOPY
202  FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
203#else
204  register JCOEFPTR inptr, outptr;
205  register long count;
206
207  inptr = (JCOEFPTR) input_row;
208  outptr = (JCOEFPTR) output_row;
209  for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) {
210    *outptr++ = *inptr++;
211  }
212#endif
213}
214
215
216GLOBAL(void)
217jzero_far (void FAR * target, size_t bytestozero)
218/* Zero out a chunk of FAR memory. */
219/* This might be sample-array data, block-array data, or alloc_large data. */
220{
221#ifdef FMEMZERO
222  FMEMZERO(target, bytestozero);
223#else
224  register char FAR * ptr = (char FAR *) target;
225  register size_t count;
226
227  for (count = bytestozero; count > 0; count--) {
228    *ptr++ = 0;
229  }
230#endif
231}
232