1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
/* Copyright (C) 1995, 1996, 1997, 1998 Aladdin Enterprises. All rights reserved.
This file is part of AFPL Ghostscript.
AFPL Ghostscript is distributed with NO WARRANTY OF ANY KIND. No author or
distributor accepts any responsibility for the consequences of using it, or
for whether it serves any particular purpose or works at all, unless he or
she says so in writing. Refer to the Aladdin Free Public License (the
"License") for full details.
Every copy of AFPL Ghostscript must include a copy of the License, normally
in a plain ASCII text file named PUBLIC. The License grants you the right
to copy, modify and redistribute AFPL Ghostscript, but only under certain
conditions described in the License. Among other things, the License
requires that the copyright notice and this notice be preserved on all
copies.
*/
/*$Id$ */
/* RunLengthEncode filter */
#include "stdio_.h" /* includes std.h */
#include "memory_.h"
#include "strimpl.h"
#include "srlx.h"
/* ------ RunLengthEncode ------ */
private_st_RLE_state();
/* Set defaults */
private void
s_RLE_set_defaults(stream_state * st)
{
stream_RLE_state *const ss = (stream_RLE_state *) st;
s_RLE_set_defaults_inline(ss);
}
/* Initialize */
private int
s_RLE_init(stream_state * st)
{
stream_RLE_state *const ss = (stream_RLE_state *) st;
return s_RLE_init_inline(ss);
}
/* Process a buffer */
private int
s_RLE_process(stream_state * st, stream_cursor_read * pr,
stream_cursor_write * pw, bool last)
{
stream_RLE_state *const ss = (stream_RLE_state *) st;
register const byte *p = pr->ptr;
register byte *q = pw->ptr;
const byte *rlimit = pr->limit;
byte *wlimit = pw->limit;
int status = 0;
ulong rleft = ss->record_left;
/*
* We thought that the Genoa CET demands that the output from this
* filter be not just legal, but optimal, so we went to the trouble
* of ensuring this. It turned out that this wasn't actually
* necessary, but we didn't want to change the code back.
*
* For optimal output, we can't just break runs at buffer
* boundaries: unless we hit a record boundary or the end of the
* input, we have to look ahead far enough to know that we aren't
* breaking a run prematurely.
*/
/* Check for leftover output. */
copy:
if (ss->copy_left) {
uint rcount = rlimit - p;
uint wcount = wlimit - q;
uint count = ss->copy_left;
if (rcount < count)
count = rcount;
if (wcount < count)
count = wcount;
if (rleft < count)
count = rleft;
memcpy(q + 1, p + 1, count);
pr->ptr = p += count;
pw->ptr = q += count;
if ((ss->record_left = rleft -= count) == 0)
ss->record_left = rleft = ss->record_size;
if ((ss->copy_left -= count) != 0)
return (rcount == 0 ? 0 : 1);
}
while (p < rlimit) {
const byte *beg = p;
const byte *p1;
uint count = rlimit - p;
bool end = last;
byte next;
if (count > rleft)
count = rleft, end = true;
if (count > 128)
count = 128, end = true;
p1 = p + count - 1;
if (count < 3) {
if (!end || count == 0)
break; /* can't look ahead far enough */
if (count == 1) {
if (wlimit - q < 2) {
status = 1;
break;
}
*++q = 0;
} else { /* count == 2 */
if (p[1] == p[2]) {
if (wlimit - q < 2) {
status = 1;
break;
}
*++q = 255;
} else {
if (wlimit - q < 3) {
status = 1;
break;
}
*++q = 1;
*++q = p[1];
}
}
*++q = p1[1];
p = p1 + 1;
} else if ((next = p[1]) == p[2] && next == p[3]) {
if (wlimit - q < 2) {
status = 1;
break;
}
/* Recognize leading repeated byte */
do {
p++;
}
while (p < p1 && p[2] == next);
if (p == p1 && !end) {
p = beg; /* need to look ahead further */
break;
}
p++;
*++q = (byte) (257 - (p - beg));
*++q = next;
} else {
p1--;
while (p < p1 && (p[2] != p[1] || p[3] != p[1]))
p++;
if (p == p1) {
if (!end) {
p = beg; /* need to look ahead further */
break;
}
p += 2;
}
count = p - beg;
if (wlimit - q < count + 1) {
p = beg;
if (q >= wlimit) {
status = 1;
break;
}
/* Copy some now and some later. */
*++q = count - 1;
ss->copy_left = count;
goto copy;
}
*++q = count - 1;
memcpy(q + 1, beg + 1, count);
q += count;
}
rleft -= p - beg;
if (rleft == 0)
rleft = ss->record_size;
}
if (last && status == 0 && ss->EndOfData) {
if (q < wlimit)
*++q = 128;
else
status = 1;
}
pr->ptr = p;
pw->ptr = q;
ss->record_left = rleft;
return status;
}
/* Stream template */
const stream_template s_RLE_template = {
&st_RLE_state, s_RLE_init, s_RLE_process, 129, 2, NULL,
s_RLE_set_defaults, s_RLE_init
};
|
