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// This is free and unencumbered software released into the public domain.
//
// Anyone is free to copy, modify, publish, use, compile, sell, or
// distribute this software, either in source code form or as a compiled
// binary, for any purpose, commercial or non-commercial, and by any
// means.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <vector>
#include <map>
int verbose = 0;
static void push_int_bits(std::vector<bool> &outbits, int value, int bits)
{
while (bits-- > 0)
outbits.push_back((value >> bits) & 1);
}
static void push_zero_bits(std::vector<bool> &outbits, int bits)
{
while (bits-- > 0)
outbits.push_back(false);
}
static int decode_int_from_bits(const std::vector<bool> &inbits, int &cursor, int bits)
{
int ret = 0;
while (bits-- > 0)
if (inbits.at(cursor++))
ret |= 1 << bits;
return ret;
}
void ice_compress(std::vector<bool> &outbits, const std::vector<bool> &inbits)
{
int opcode_stats_d4 = 0;
int opcode_stats_d32 = 0;
int opcode_stats_d256 = 0;
int opcode_stats_raw = 0;
int opcode_stats_d8M = 0;
int opcode_stats_end = 0;
std::vector<int> deltas;
int numzeros = 0;
for (auto bit : inbits)
{
if (bit) {
deltas.push_back(numzeros);
numzeros = 0;
} else {
numzeros++;
}
}
for (int i = 0; i < int(deltas.size()); i++)
{
int raw_len = 0;
int compr_len = 0;
int best_compr_raw_diff = -1;
int best_compr_raw_idx = -1;
int best_compr_raw_len = -1;
for (int j = 0; j+i < int(deltas.size()); j++)
{
int delta = deltas.at(i + j);
raw_len += delta + 1;
if (delta < 4)
compr_len += 3;
else if (delta < 32)
compr_len += 7;
else if (delta < 256)
compr_len += 11;
else
compr_len += 26;
if (compr_len - raw_len < std::max(best_compr_raw_diff - 4, 0) || raw_len > 64)
break;
if (compr_len - raw_len > best_compr_raw_diff) {
best_compr_raw_diff = compr_len - raw_len;
best_compr_raw_idx = j;
best_compr_raw_len = raw_len;
}
}
if (best_compr_raw_diff > 9)
{
opcode_stats_raw++;
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(true);
push_int_bits(outbits, best_compr_raw_len-1, 6);
for (int j = 0; j <= best_compr_raw_idx; j++) {
int delta = deltas.at(i + j);
for (int k = 0; k < delta; k++)
outbits.push_back(false);
if (j < best_compr_raw_idx)
outbits.push_back(true);
}
i += best_compr_raw_idx;
continue;
}
int delta = deltas.at(i);
if (delta < 4) {
opcode_stats_d4++;
outbits.push_back(true);
push_int_bits(outbits, delta, 2);
} else
if (delta < 32) {
opcode_stats_d32++;
outbits.push_back(false);
outbits.push_back(true);
push_int_bits(outbits, delta, 5);
} else
if (delta < 256) {
opcode_stats_d256++;
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(true);
push_int_bits(outbits, delta, 8);
} else {
opcode_stats_d8M++;
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(true);
push_int_bits(outbits, delta, 23);
}
}
opcode_stats_end++;
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(false);
outbits.push_back(false);
push_int_bits(outbits, numzeros, 23);
if (verbose > 1) {
fprintf(stderr, "opcode d4 %5d\n", opcode_stats_d4);
fprintf(stderr, "opcode d32 %5d\n", opcode_stats_d32);
fprintf(stderr, "opcode d256 %5d\n", opcode_stats_d256);
fprintf(stderr, "opcode raw %5d\n", opcode_stats_raw);
fprintf(stderr, "opcode d8M %5d\n", opcode_stats_d8M);
fprintf(stderr, "opcode end %5d\n", opcode_stats_end);
}
}
void ice_uncompress(std::vector<bool> &outbits, const std::vector<bool> &inbits)
{
int cursor = 0;
while (cursor < int(inbits.size()))
{
if (inbits.at(cursor++)) {
int zeros = decode_int_from_bits(inbits, cursor, 2);
push_zero_bits(outbits, zeros);
outbits.push_back(true);
} else
if (inbits.at(cursor++)) {
int zeros = decode_int_from_bits(inbits, cursor, 5);
push_zero_bits(outbits, zeros);
outbits.push_back(true);
} else
if (inbits.at(cursor++)) {
int zeros = decode_int_from_bits(inbits, cursor, 8);
push_zero_bits(outbits, zeros);
outbits.push_back(true);
} else
if (inbits.at(cursor++)) {
int raw_len = decode_int_from_bits(inbits, cursor, 6);
while (raw_len--)
outbits.push_back(inbits.at(cursor++));
outbits.push_back(true);
} else
if (inbits.at(cursor++)) {
int zeros = decode_int_from_bits(inbits, cursor, 23);
push_zero_bits(outbits, zeros);
outbits.push_back(true);
} else {
int zeros = decode_int_from_bits(inbits, cursor, 23);
push_zero_bits(outbits, zeros);
}
}
}
void help()
{
printf("\n");
printf("Usage: icecompr [-v] [input-file [output-file]]\n");
printf("\n");
exit(1);
}
int main(int argc, char **argv)
{
FILE *input_file = stdin;
FILE *output_file = stdout;
int opt;
while ((opt = getopt(argc, argv, "v")) != -1)
{
switch (opt)
{
case 'v':
verbose++;
break;
default:
help();
}
}
if (optind < argc) {
input_file = fopen(argv[optind], "rb");
if (input_file == NULL) {
fprintf(stderr, "Failed to open input file `%s': %s\n", argv[optind], strerror(errno));
return 1;
}
optind++;
}
if (optind < argc) {
output_file = fopen(argv[optind], "wb");
if (output_file == NULL) {
fprintf(stderr, "Failed to open output file `%s': %s\n", argv[optind], strerror(errno));
return 1;
}
optind++;
}
if (optind != argc)
help();
std::vector<bool> original_bits;
int count_set_bits = 0;
while (1)
{
int byte = fgetc(input_file);
if (byte < 0)
break;
// MSB first
for (int i = 7; i >= 0; i--) {
bool bit = (byte >> i) & 1;
if (bit) count_set_bits++;
original_bits.push_back(bit);
}
}
int uncompressed_size = original_bits.size();
if (verbose > 0) {
fprintf(stderr, "Percentage of set bits: %.2f%%\n", (100.0*count_set_bits) / uncompressed_size);
fprintf(stderr, "Uncompressed size: %8d bits\n", uncompressed_size);
}
std::vector<bool> compressed_bits;
ice_compress(compressed_bits, original_bits);
int compressed_size = compressed_bits.size();
if (verbose > 0) {
fprintf(stderr, "Compressed size: %8d bits\n", compressed_size);
fprintf(stderr, "Space savings: %.2f%%\n", 100 - (100.0*compressed_size) / uncompressed_size);
}
std::vector<bool> uncompressed_bits;
ice_uncompress(uncompressed_bits, compressed_bits);
bool check_ok = original_bits == uncompressed_bits;
if (verbose > 0 || !check_ok) {
fprintf(stderr, "Integrity check: %s\n", check_ok ? "OK" : "ERROR");
if (!check_ok)
return 1;
}
fprintf(output_file, "ICECOMPR");
for (int i = 0; i < int(compressed_bits.size()); i += 8) {
int value = 0;
for (int j = 0; j < 8 && i+j < int(compressed_bits.size()); j++)
if (compressed_bits.at(i+j))
value |= 1 << (7-j);
fputc(value, output_file);
}
return 0;
}
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