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
|
/*
* (c) Copyright 2021 by Einar Saukas. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * The name of its author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include "zx0.h"
#define MAX_SCALE 50
int offset_ceiling(int index, int offset_limit) {
return index > offset_limit ? offset_limit : index < INITIAL_OFFSET ? INITIAL_OFFSET : index;
}
int elias_gamma_bits(int value) {
int bits = 1;
while (value >>= 1)
bits += 2;
return bits;
}
BLOCK* zx0_optimize(unsigned char *input_data, int input_size, int skip, int offset_limit) {
BLOCK **last_literal;
BLOCK **last_match;
BLOCK **optimal;
int* match_length;
int* best_length;
int best_length_size;
int bits;
int index;
int offset;
int length;
int bits2;
int dots = 2;
int max_offset = offset_ceiling(input_size-1, offset_limit);
/* allocate all main data structures at once */
last_literal = (BLOCK **)calloc(max_offset+1, sizeof(BLOCK *));
last_match = (BLOCK **)calloc(max_offset+1, sizeof(BLOCK *));
optimal = (BLOCK **)calloc(input_size, sizeof(BLOCK *));
match_length = (int *)calloc(max_offset+1, sizeof(int));
best_length = (int *)malloc(input_size*sizeof(int));
if (!last_literal || !last_match || !optimal || !match_length || !best_length) {
fprintf(stderr, "Error: Insufficient memory\n");
exit(1);
}
best_length[2] = 2;
/* start with fake block */
assign(&last_match[INITIAL_OFFSET], allocate(-1, skip-1, INITIAL_OFFSET, NULL));
printf("[");
/* process remaining bytes */
for (index = skip; index < input_size; index++) {
best_length_size = 2;
max_offset = offset_ceiling(index, offset_limit);
for (offset = 1; offset <= max_offset; offset++) {
if (index != skip && index >= offset && input_data[index] == input_data[index-offset]) {
/* copy from last offset */
if (last_literal[offset]) {
length = index-last_literal[offset]->index;
bits = last_literal[offset]->bits + 1 + elias_gamma_bits(length);
assign(&last_match[offset], allocate(bits, index, offset, last_literal[offset]));
if (!optimal[index] || optimal[index]->bits > bits)
assign(&optimal[index], last_match[offset]);
}
/* copy from new offset */
if (++match_length[offset] > 1) {
if (best_length_size < match_length[offset]) {
bits = optimal[index-best_length[best_length_size]]->bits + elias_gamma_bits(best_length[best_length_size]-1);
do {
best_length_size++;
bits2 = optimal[index-best_length_size]->bits + elias_gamma_bits(best_length_size-1);
if (bits2 <= bits) {
best_length[best_length_size] = best_length_size;
bits = bits2;
} else {
best_length[best_length_size] = best_length[best_length_size-1];
}
} while(best_length_size < match_length[offset]);
}
length = best_length[match_length[offset]];
bits = optimal[index-length]->bits + 8 + elias_gamma_bits((offset-1)/128+1) + elias_gamma_bits(length-1);
if (!last_match[offset] || last_match[offset]->index != index || last_match[offset]->bits > bits) {
assign(&last_match[offset], allocate(bits, index, offset, optimal[index-length]));
if (!optimal[index] || optimal[index]->bits > bits)
assign(&optimal[index], last_match[offset]);
}
}
} else {
/* copy literals */
match_length[offset] = 0;
if (last_match[offset]) {
length = index-last_match[offset]->index;
bits = last_match[offset]->bits + 1 + elias_gamma_bits(length) + length*8;
assign(&last_literal[offset], allocate(bits, index, 0, last_match[offset]));
if (!optimal[index] || optimal[index]->bits > bits)
assign(&optimal[index], last_literal[offset]);
}
}
}
/* indicate progress */
if (index*MAX_SCALE/input_size > dots) {
printf(".");
fflush(stdout);
dots++;
}
}
printf("]\n");
return optimal[input_size-1];
}
|
