/proc/self/cwd/external/libjpeg_turbo/jutils.c
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1 | | /* |
2 | | * jutils.c |
3 | | * |
4 | | * This file was part of the Independent JPEG Group's software: |
5 | | * Copyright (C) 1991-1996, Thomas G. Lane. |
6 | | * libjpeg-turbo Modifications: |
7 | | * Copyright (C) 2022, D. R. Commander. |
8 | | * For conditions of distribution and use, see the accompanying README.ijg |
9 | | * file. |
10 | | * |
11 | | * This file contains tables and miscellaneous utility routines needed |
12 | | * for both compression and decompression. |
13 | | * Note we prefix all global names with "j" to minimize conflicts with |
14 | | * a surrounding application. |
15 | | */ |
16 | | |
17 | | #define JPEG_INTERNALS |
18 | | #include "jinclude.h" |
19 | | #include "jpeglib.h" |
20 | | |
21 | | |
22 | | /* |
23 | | * jpeg_zigzag_order[i] is the zigzag-order position of the i'th element |
24 | | * of a DCT block read in natural order (left to right, top to bottom). |
25 | | */ |
26 | | |
27 | | #if 0 /* This table is not actually needed in v6a */ |
28 | | |
29 | | const int jpeg_zigzag_order[DCTSIZE2] = { |
30 | | 0, 1, 5, 6, 14, 15, 27, 28, |
31 | | 2, 4, 7, 13, 16, 26, 29, 42, |
32 | | 3, 8, 12, 17, 25, 30, 41, 43, |
33 | | 9, 11, 18, 24, 31, 40, 44, 53, |
34 | | 10, 19, 23, 32, 39, 45, 52, 54, |
35 | | 20, 22, 33, 38, 46, 51, 55, 60, |
36 | | 21, 34, 37, 47, 50, 56, 59, 61, |
37 | | 35, 36, 48, 49, 57, 58, 62, 63 |
38 | | }; |
39 | | |
40 | | #endif |
41 | | |
42 | | /* |
43 | | * jpeg_natural_order[i] is the natural-order position of the i'th element |
44 | | * of zigzag order. |
45 | | * |
46 | | * When reading corrupted data, the Huffman decoders could attempt |
47 | | * to reference an entry beyond the end of this array (if the decoded |
48 | | * zero run length reaches past the end of the block). To prevent |
49 | | * wild stores without adding an inner-loop test, we put some extra |
50 | | * "63"s after the real entries. This will cause the extra coefficient |
51 | | * to be stored in location 63 of the block, not somewhere random. |
52 | | * The worst case would be a run-length of 15, which means we need 16 |
53 | | * fake entries. |
54 | | */ |
55 | | |
56 | | const int jpeg_natural_order[DCTSIZE2 + 16] = { |
57 | | 0, 1, 8, 16, 9, 2, 3, 10, |
58 | | 17, 24, 32, 25, 18, 11, 4, 5, |
59 | | 12, 19, 26, 33, 40, 48, 41, 34, |
60 | | 27, 20, 13, 6, 7, 14, 21, 28, |
61 | | 35, 42, 49, 56, 57, 50, 43, 36, |
62 | | 29, 22, 15, 23, 30, 37, 44, 51, |
63 | | 58, 59, 52, 45, 38, 31, 39, 46, |
64 | | 53, 60, 61, 54, 47, 55, 62, 63, |
65 | | 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ |
66 | | 63, 63, 63, 63, 63, 63, 63, 63 |
67 | | }; |
68 | | |
69 | | |
70 | | /* |
71 | | * Arithmetic utilities |
72 | | */ |
73 | | |
74 | | GLOBAL(long) |
75 | | jdiv_round_up(long a, long b) |
76 | | /* Compute a/b rounded up to next integer, ie, ceil(a/b) */ |
77 | | /* Assumes a >= 0, b > 0 */ |
78 | 12.6k | { |
79 | 12.6k | return (a + b - 1L) / b; |
80 | 12.6k | } |
81 | | |
82 | | |
83 | | GLOBAL(long) |
84 | | jround_up(long a, long b) |
85 | | /* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */ |
86 | | /* Assumes a >= 0, b > 0 */ |
87 | 681 | { |
88 | 681 | a += b - 1L; |
89 | 681 | return a - (a % b); |
90 | 681 | } |
91 | | |
92 | | |
93 | | GLOBAL(void) |
94 | | jcopy_sample_rows(JSAMPARRAY input_array, int source_row, |
95 | | JSAMPARRAY output_array, int dest_row, int num_rows, |
96 | | JDIMENSION num_cols) |
97 | | /* Copy some rows of samples from one place to another. |
98 | | * num_rows rows are copied from input_array[source_row++] |
99 | | * to output_array[dest_row++]; these areas may overlap for duplication. |
100 | | * The source and destination arrays must be at least as wide as num_cols. |
101 | | */ |
102 | 1.71M | { |
103 | 1.71M | register JSAMPROW inptr, outptr; |
104 | 1.71M | register size_t count = (size_t)(num_cols * sizeof(JSAMPLE)); |
105 | 1.71M | register int row; |
106 | | |
107 | 1.71M | input_array += source_row; |
108 | 1.71M | output_array += dest_row; |
109 | | |
110 | 3.49M | for (row = num_rows; row > 0; row--) { |
111 | 1.78M | inptr = *input_array++; |
112 | 1.78M | outptr = *output_array++; |
113 | 1.78M | memcpy(outptr, inptr, count); |
114 | 1.78M | } |
115 | 1.71M | } |
116 | | |
117 | | |
118 | | GLOBAL(void) |
119 | | jcopy_block_row(JBLOCKROW input_row, JBLOCKROW output_row, |
120 | | JDIMENSION num_blocks) |
121 | | /* Copy a row of coefficient blocks from one place to another. */ |
122 | 0 | { |
123 | 0 | memcpy(output_row, input_row, num_blocks * (DCTSIZE2 * sizeof(JCOEF))); |
124 | 0 | } |
125 | | |
126 | | |
127 | | GLOBAL(void) |
128 | | jzero_far(void *target, size_t bytestozero) |
129 | | /* Zero out a chunk of memory. */ |
130 | | /* This might be sample-array data, block-array data, or alloc_large data. */ |
131 | 2.45M | { |
132 | 2.45M | memset(target, 0, bytestozero); |
133 | 2.45M | } |