jutils.c
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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)
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)
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 }
char JSAMPLE
Definition: jmorecfg.h:64
JSAMPLE FAR * JSAMPROW
Definition: jpeglib.h:66
png_voidp ptr
Definition: png.h:2063
#define FMEMZERO(target, size)
Definition: jutils.c:101
#define SIZEOF(object)
Definition: jinclude.h:80
short JCOEF
Definition: jmorecfg.h:99
long b
Definition: jpegint.h:371
jround_up(long a, long b)
Definition: jutils.c:81
#define FMEMCOPY(dest, src, size)
Definition: jutils.c:100
int JSAMPARRAY int dest_row
Definition: jpegint.h:373
#define DCTSIZE2
Definition: jpeglib.h:42
JBLOCKROW JDIMENSION num_blocks
Definition: jpegint.h:376
int JSAMPARRAY int int num_rows
Definition: jpegint.h:373
int source_row
Definition: jpegint.h:373
JBLOCKROW output_row
Definition: jpegint.h:376
jdiv_round_up(long a, long b)
Definition: jutils.c:72
JBLOCK FAR * JBLOCKROW
Definition: jpeglib.h:71
#define FAR
Definition: jmorecfg.h:215
size_t bytestozero
Definition: jpegint.h:378
string a
png_bytepp row
Definition: png.h:1759
int JSAMPARRAY int int JDIMENSION num_cols
Definition: jpegint.h:373
jzero_far(void FAR *target, size_t bytestozero)
Definition: jutils.c:165
JCOEF FAR * JCOEFPTR
Definition: jpeglib.h:75
JSAMPROW * JSAMPARRAY
Definition: jpeglib.h:67
const int jpeg_natural_order[DCTSIZE2+16]
Definition: jutils.c:53
#define GLOBAL(type)
Definition: jmorecfg.h:188
jcopy_block_row(JBLOCKROW input_row, JBLOCKROW output_row, JDIMENSION num_blocks)
Definition: jutils.c:145
unsigned int JDIMENSION
Definition: jmorecfg.h:171
jcopy_sample_rows(JSAMPARRAY input_array, int source_row, JSAMPARRAY output_array, int dest_row, int num_rows, JDIMENSION num_cols)
Definition: jutils.c:111
int JSAMPARRAY output_array
Definition: jpegint.h:373


openhrp3
Author(s): AIST, General Robotix Inc., Nakamura Lab of Dept. of Mechano Informatics at University of Tokyo
autogenerated on Thu Sep 8 2022 02:24:04