Update lzcomp

This commit is contained in:
Rangi 2020-05-24 12:29:05 -04:00
parent c1c671d84b
commit 159cef004f
4 changed files with 53 additions and 9 deletions

View File

@ -37,13 +37,16 @@ struct command * compress (const unsigned char * data, unsigned short * size, un
} else {
struct command * compressed_sequences[COMPRESSION_METHODS];
unsigned short lengths[COMPRESSION_METHODS];
unsigned flags = compressor -> methods;
unsigned flags = 0;
for (current = 0; current < COMPRESSION_METHODS; current ++) {
lengths[current] = *size;
if (!flags) flags = (++ compressor) -> methods;
compressed_sequences[current] = compressor -> function(data, bitflipped, lengths + current, -- flags);
if (flags == compressor -> methods) {
flags = 0;
compressor ++;
}
result = select_command_sequence(compressed_sequences, lengths, COMPRESSION_METHODS, size);
compressed_sequences[current] = compressor -> function(data, bitflipped, lengths + current, flags ++);
}
result = select_optimal_sequence(compressed_sequences, lengths, size);
for (current = 0; current < COMPRESSION_METHODS; current ++) free(compressed_sequences[current]);
}
free(bitflipped);

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@ -1,8 +1,47 @@
#include "proto.h"
struct command * select_command_sequence (struct command ** sequences, const unsigned short * lengths, unsigned count, unsigned short * final_length) {
struct command * select_optimal_sequence (struct command ** sequences, const unsigned short * lengths, unsigned short * final_length) {
struct command * compressor_sequences[NUM_COMPRESSORS * 2];
unsigned short compressor_lengths[NUM_COMPRESSORS * 2];
struct command * inverted_sequences[COMPRESSION_METHODS];
unsigned short inverted_lengths[COMPRESSION_METHODS];
unsigned p, current, method = 0;
for (current = 0; current < NUM_COMPRESSORS; current ++) {
compressor_sequences[current] = select_command_sequence(sequences + method, lengths + method, compressors[current].methods, compressor_lengths + current);
compressor_sequences[current + NUM_COMPRESSORS] = select_command_sequence(sequences + method, lengths + method, -(int) compressors[current].methods,
compressor_lengths + (current + NUM_COMPRESSORS));
for (p = 0; p < compressors[current].methods; p ++) {
inverted_sequences[method + compressors[current].methods - 1 - p] = sequences[method + p];
inverted_lengths[method + compressors[current].methods - 1 - p] = lengths[method + p];
}
method += compressors[current].methods;
}
unsigned short final_lengths[8];
struct command * final_sequences[8] = {
select_command_sequence(compressor_sequences, compressor_lengths, NUM_COMPRESSORS, final_lengths),
select_command_sequence(compressor_sequences, compressor_lengths, -NUM_COMPRESSORS, final_lengths + 1),
select_command_sequence(compressor_sequences + NUM_COMPRESSORS, compressor_lengths + NUM_COMPRESSORS, NUM_COMPRESSORS, final_lengths + 2),
select_command_sequence(compressor_sequences + NUM_COMPRESSORS, compressor_lengths + NUM_COMPRESSORS, -NUM_COMPRESSORS, final_lengths + 3),
select_command_sequence(sequences, lengths, COMPRESSION_METHODS, final_lengths + 4),
select_command_sequence(sequences, lengths, -COMPRESSION_METHODS, final_lengths + 5),
select_command_sequence(inverted_sequences, inverted_lengths, COMPRESSION_METHODS, final_lengths + 6),
select_command_sequence(inverted_sequences, inverted_lengths, -COMPRESSION_METHODS, final_lengths + 7)
};
for (current = 0; current < (2 * NUM_COMPRESSORS); current ++) free(compressor_sequences[current]);
struct command * result = select_command_sequence(final_sequences, final_lengths, 8, final_length);
for (current = 0; current < 8; current ++) free(final_sequences[current]);
return result;
}
struct command * select_command_sequence (struct command ** sequences, const unsigned short * lengths, int count, unsigned short * final_length) {
// negative count indicates iterating backwards
unsigned short min_sequence = 0, min_length = compressed_length(*sequences, *lengths);
unsigned short seq, len;
int backwards = 0;
if (count < 0) {
backwards = 1;
count = -count;
}
for (seq = 1; seq < count; seq ++) {
len = compressed_length(sequences[seq], lengths[seq]);
if (len < min_length) {
@ -15,7 +54,9 @@ struct command * select_command_sequence (struct command ** sequences, const uns
memcpy(current, sequences[min_sequence], *final_length * sizeof(struct command));
struct command * new;
for (seq = 1; seq < count; seq ++) {
if (backwards) seq = count - seq;
new = merge_command_sequences(current, *final_length, sequences[(seq + min_sequence) % count], lengths[(seq + min_sequence) % count], final_length);
if (backwards) seq = count - seq; // restore the value for the loop
free(current);
current = new;
}

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@ -17,7 +17,7 @@ void optimize (struct command * commands, unsigned short count) {
next -> command = 7;
continue;
}
if (next -> command == commands -> command) {
if (next -> command == commands -> command)
switch (commands -> command) {
case 0:
if ((commands -> value + commands -> count) != next -> value) break;
@ -40,8 +40,6 @@ void optimize (struct command * commands, unsigned short count) {
}
next -> count = (commands -> count + next -> count) - MAX_COMMAND_COUNT;
commands -> count = MAX_COMMAND_COUNT;
break;
}
}
commands = next;
}

View File

@ -3,6 +3,7 @@
#include <string.h>
#include <stdarg.h>
#define NUM_COMPRESSORS 4
#define COMPRESSION_METHODS 96 /* sum of all values for the methods field in compressors */
#define MAX_FILE_SIZE 32768
#define SHORT_COMMAND_COUNT 32
@ -48,7 +49,8 @@ int main(int, char **);
struct command * compress(const unsigned char *, unsigned short *, unsigned);
// merging.c
struct command * select_command_sequence(struct command **, const unsigned short *, unsigned, unsigned short *);
struct command * select_optimal_sequence(struct command **, const unsigned short *, unsigned short *);
struct command * select_command_sequence(struct command **, const unsigned short *, int, unsigned short *);
struct command * merge_command_sequences(const struct command *, unsigned short, const struct command *, unsigned short, unsigned short *);
// mpcomp.c