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package compressors;
/**
* Pokemon Gen 2 sprite decompressor Source:
* https://github.com/pret/pokemon-reverse-engineering-tools/blob/master/pokemontools/lz.py
* (and gfx.py for flatten())
* Ported to Java by sneed
*
*/
public class Gen2Decmp {
private static final int LZ_END = 0xFF;
private static final int INITIAL_BUF_SIZE = 0x1000;
public byte[] data;
private int address;
private byte[] output;
private int out_idx;
private int cmd;
private int len;
private int offset;
private static int[] bit_flipped;
static {
bit_flipped = new int[0x100];
for (int b = 0; b < 0x100; b++) {
for (int i = 0; i < 8; i++) {
bit_flipped[b] += ((b >> i) & 1) << (7 - i);
}
}
}
public Gen2Decmp(byte[] input, int baseOffset, int tilesWide, int tilesHigh) {
this.data = input;
this.address = baseOffset;
decompress();
cutAndTranspose(tilesWide, tilesHigh);
}
public byte[] getData() {
return output;
}
public byte[] getFlattenedData() {
return flatten(output);
}
private void cutAndTranspose(int width, int height) {
if (output == null) {
return;
}
int tiles = width * height;
byte[] newData = new byte[width * height * 16];
for (int tile = 0; tile < tiles; tile++) {
int oldTileX = tile % width;
int oldTileY = tile / width;
int newTileNum = oldTileX * height + oldTileY;
System.arraycopy(output, tile * 16, newData, newTileNum * 16, 16);
}
output = newData;
}
private void decompress() {
output = new byte[INITIAL_BUF_SIZE];
while (true) {
if (this.peek() == LZ_END) {
this.next();
break;
}
cmd = (this.peek() & 0xE0) >> 5;
if (cmd == 7) {
// LONG command
cmd = (this.peek() & 0x1C) >> 2;
len = (this.next() & 0x03) * 0x100 + this.next() + 1;
} else {
// Normal length
len = (this.next() & 0x1F) + 1;
}
while (out_idx + len > output.length) {
resizeOutput();
}
switch (cmd) {
case 0:
// Literal
System.arraycopy(data, address, output, out_idx, len);
out_idx += len;
address += len;
break;
case 1:
// Iterate
byte repe = (byte) next();
for (int i = 0; i < len; i++) {
output[out_idx++] = repe;
}
break;
case 2:
// Alternate
byte[] alts = { (byte) next(), (byte) next() };
for (int i = 0; i < len; i++) {
output[out_idx++] = alts[i & 1];
}
break;
case 3:
// Zero-fill
// Easy, since Java arrays are initialized to 0.
out_idx += len;
break;
case 4:
// Default repeat
repeat();
break;
case 5:
repeat(1, bit_flipped);
break;
case 6:
repeat(-1, null);
break;
}
}
byte[] finalOutput = new byte[out_idx];
System.arraycopy(output, 0, finalOutput, 0, out_idx);
output = finalOutput;
}
private void repeat() {
repeat(1, null);
}
private void repeat(int direction, int[] table) {
get_offset();
for (int i = 0; i < len; i++) {
int value = output[offset + i * direction] & 0xFF;
output[out_idx++] = (byte) ((table == null) ? value : table[value]);
}
}
private void get_offset() {
if (this.peek() >= 0x80) {
// Negative
offset = this.next() & 0x7F;
offset = out_idx - offset - 1;
} else {
// Positive, extended
offset = this.next() * 0x100 + this.next();
}
}
private void resizeOutput() {
byte[] newOut = new byte[output.length * 2];
System.arraycopy(output, 0, newOut, 0, out_idx);
output = newOut;
}
private int peek() {
return data[address] & 0xFF;
}
public int next() {
return data[address++] & 0xFF;
}
private static byte[] flatten(byte[] planar) {
byte[] strips = new byte[planar.length * 4];
for (int j = 0; j < planar.length / 2; j++) {
int bottom = planar[j * 2] & 0xFF;
int top = planar[j * 2 + 1] & 0xFF;
byte[] strip = new byte[8];
for (int i = 7; i >= 0; i--) {
strip[7 - i] = (byte) (((bottom >>> i) & 1) + ((top * 2 >>> i) & 2));
}
System.arraycopy(strip, 0, strips, j * 8, 8);
}
return strips;
}
}
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