// LZSS decompressor
#include <stdio.h>
#include <stdlib.h>
#include <sys\stat.h>
char *decode_lzss_stuff(FILE *fp_i, unsigned int *length_ptr) {
unsigned char *outbuffer = NULL; // decoded data
// should check for size overflow, but I'm going to be stupid and not do so
unsigned int buffersize = 163840; // arbitrary initial size
//unsigned char curbyte, controlbyte;
unsigned char controlbyte;
unsigned int bufferindex = 0;
unsigned int i = 0; // used for looping
unsigned char tempbuffer[10]; // actually only 2-3 bytes should be needed
unsigned int num_bytes_to_copy = 0;
unsigned int backwards_offset = 0;
unsigned int iter_count = 0;
int copy_start_index = 0;
unsigned int copy_counter = 0;
outbuffer = malloc(buffersize);
if(outbuffer == NULL) {
printf("Unable to allocate memory.\n");
return NULL;
}
// copy the first 16 bytes
for(i = 0; i < 16; i++) {
outbuffer[bufferindex] = fgetc(fp_i);
bufferindex++;
}
//check that the next byte is 0x11
if (fgetc(fp_i) != 0x11) {
printf("Input file does not appear to be LZSS compressed.\n");
exit(-1);
}
//skip the next 3 bytes
for(i = 0; i < 3; i++) {
fgetc(fp_i);
}
while(!feof(fp_i)) {
if(bufferindex > (buffersize-8000)) { // give a big safety margin for fun
buffersize *= 2; // increase buffer size
outbuffer = realloc(outbuffer, buffersize);
if(outbuffer == NULL) {
printf("Unable to allocate memory.\n");
return NULL;
}
}
controlbyte = fgetc(fp_i);
if(feof(fp_i)) {
continue;
}
//printf("Control byte: 0x%02x\n", controlbyte);
//if(bufferindex > 0xC70 && bufferindex < 0xCF0) {
/*if(bufferindex > 0xC70) {
printf("Control byte: 0x%02x\n", controlbyte);
}*/
for(i = 0; i < 8; i++) {
if(controlbyte & (0x80 >> i)) {
//printf("Encoded data...\n");
// decode encoded data
tempbuffer[0] = fgetc(fp_i);
tempbuffer[1] = fgetc(fp_i);
if((tempbuffer[0] & 0xF0) == 0x10) {
tempbuffer[2] = fgetc(fp_i);
tempbuffer[3] = fgetc(fp_i);
num_bytes_to_copy = (((unsigned int) (tempbuffer[0] & 0x0F)) * 0x1000) + (((unsigned int) tempbuffer[1]) * 0x10) + (tempbuffer[2] >> 4) + 0x111;
backwards_offset = (((unsigned int) (tempbuffer[2] & 0x0F)) * 0x100) + tempbuffer[3] + 1;
}
// if the first nibble is 0, get a third byte
else if((tempbuffer[0] & 0xF0) == 0) {
tempbuffer[2] = fgetc(fp_i);
//printf("0x %02x %02x %02x\n", tempbuffer[0], tempbuffer[1], tempbuffer[2]);
//*length_ptr = bufferindex;
//return outbuffer;
//num_bytes_to_copy = (((unsigned int) tempbuffer[0] >> 4) * 0x100) + tempbuffer[2] + 0x2F;
//num_bytes_to_copy = (((unsigned int) tempbuffer[0] >> 4) * 0x100) + tempbuffer[2] + 0x13;
num_bytes_to_copy = (((unsigned int) tempbuffer[0]) * 0x10) + (tempbuffer[1] >> 4) + 0x11;
backwards_offset = (((unsigned int) (tempbuffer[1] & 0x0F)) * 0x100) + tempbuffer[2] + 1;
//backwards_offset = (((unsigned int) (tempbuffer[0] & 0x0F)) * 0x100) + tempbuffer[1];
//printf("0x %02x %02x %02x #B %x\n", tempbuffer[0], tempbuffer[1], tempbuffer[2], num_bytes_to_copy);
}
else {
tempbuffer[2] = 0x00;
//printf("0x %02x %02x\n", tempbuffer[0], tempbuffer[1]);
num_bytes_to_copy = (tempbuffer[0] >> 4) + 0x01;
//num_bytes_to_copy = (tempbuffer[0] >> 4) - 0x00;
backwards_offset = (((unsigned int) (tempbuffer[0] & 0x0F)) * 0x100) + tempbuffer[1] + 1;
//backwards_offset = (((unsigned int) (tempbuffer[0] & 0x0F)) * 0x100) + tempbuffer[1] - 2;
}
if(backwards_offset <= 0) {
printf("Error: Backwards offset is <= 0, this probably is wrong.\n");
}
else {
//printf("0x%03x bytes to copy, from an backwards offset of 0x%03x.\n",
// num_bytes_to_copy, backwards_offset);
copy_start_index = bufferindex - backwards_offset;
if(copy_start_index < 0) {
printf("Error: Copy start index is < 0, this probably is wrong.\n");
}
for(copy_counter = 0; copy_counter < num_bytes_to_copy; copy_counter++) {
if(bufferindex > (buffersize - 16)) {
printf("Buffer overflow ahoy! Trying to save things! bufferindex = %d\n", bufferindex);
break;
}
else if((copy_start_index + copy_counter) >= bufferindex) {
printf("Copying uninitialized data? I think not!\n");
//printf("copy_start_index = %d\n", copy_start_index);
//printf("copy_counter = %d\n", copy_counter);
//printf("Backwards offset coding bytes: 0x %02x %02x %02x\n",
// tempbuffer[0], tempbuffer[1], tempbuffer[2]);
//printf("num_bytes_to_copy = %d\n", num_bytes_to_copy);
//printf("backwards_offset = %d\n", backwards_offset);
//printf("bufferindex = %d\n", bufferindex);
//printf("buffersize = %d\n", buffersize);
break;
}
else {
outbuffer[bufferindex] = outbuffer[copy_start_index + copy_counter];
bufferindex++;
}
} // end copy loop
//if(bufferindex > 0xC70 && bufferindex < 0xCF0) {
/*if(bufferindex > 0xC70) {
printf("(end copy loop)\n");
}*/
} // end valid backwards offset
} // end encoded data
else {
outbuffer[bufferindex] = fgetc(fp_i);
//if(bufferindex > 0xC70 && bufferindex < 0xCF0) {
/*if(bufferindex > 0xC70) {
printf("0x%02x (literal)\n", outbuffer[bufferindex]);
}*/
bufferindex++;
} // end literal data
}
/*if(iter_count > 40) {
break;
}*/
iter_count++;
}
if(length_ptr != NULL) {
*length_ptr = bufferindex;
}
else {
printf("Hey, invalid length pointer supplied!\n");
}
return outbuffer;
}
int main(int argc, char *argv[]) {
FILE *fp_i, *fp_o;
unsigned char curbyte = 0;
unsigned int i = 0;
unsigned int decoded_length = 0;
//int startfound = 0;
char *outbuffer = NULL;
if(argc != 3) {
printf("Usage: bin2jpg input_file output_file\n");
exit(-1);
}
fp_i = fopen(argv[1], "rb");
if(fp_i == NULL) {
printf("Error opening input file %s.\n", argv[1]);
exit(-1);
}
fp_o = fopen(argv[2], "wb");
if(fp_o == NULL) {
printf("Error opening output file %s.\n", argv[2]);
fclose(fp_i);
exit(-1);
}
outbuffer = decode_lzss_stuff(fp_i, &decoded_length);
// write the output, dropping the first 3c bytes to get to the start of the JPG data
fwrite(outbuffer, 1, decoded_length, fp_o);
// TODO: drop data past the end of JPG marker?
if(outbuffer != NULL) {
free(outbuffer);
}
fclose(fp_i);
fclose(fp_o);
chmod(argv[2], 0777); // for some reason umask didn't seem to work for this
return 0;
}
If anyone wants to help, any stages you could post would be appreciated, especially if you can accurately describe the whole thing (particularly stuff that's not easy to tell from the 160x120 thumbnail), and especially pairs of stages that only differ in one thing (name, comment, music, one piece flipped horizontally, one piece enlarged, one piece switched for another, etc.)
