FranLMSP/pokemon_sprite_decompress
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Franco Colmenarez 2021-05-16 20:08:25 -05:00
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.gitignore vendored Normal file
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/target
*.pkz
.vscode

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Cargo.lock generated Normal file
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# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
[[package]]
name = "bitflags"
version = "1.2.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
[[package]]
name = "libc"
version = "0.2.94"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "18794a8ad5b29321f790b55d93dfba91e125cb1a9edbd4f8e3150acc771c1a5e"
[[package]]
name = "numtoa"
version = "0.1.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "b8f8bdf33df195859076e54ab11ee78a1b208382d3a26ec40d142ffc1ecc49ef"
[[package]]
name = "pokemon_sprite"
version = "0.1.0"
dependencies = [
"termion",
]
[[package]]
name = "redox_syscall"
version = "0.2.8"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "742739e41cd49414de871ea5e549afb7e2a3ac77b589bcbebe8c82fab37147fc"
dependencies = [
"bitflags",
]
[[package]]
name = "redox_termios"
version = "0.1.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "8440d8acb4fd3d277125b4bd01a6f38aee8d814b3b5fc09b3f2b825d37d3fe8f"
dependencies = [
"redox_syscall",
]
[[package]]
name = "termion"
version = "1.5.6"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "077185e2eac69c3f8379a4298e1e07cd36beb962290d4a51199acf0fdc10607e"
dependencies = [
"libc",
"numtoa",
"redox_syscall",
"redox_termios",
]

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Cargo.toml Normal file
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[package]
name = "pokemon_sprite"
version = "0.1.0"
authors = ["Franco Colmenarez <info@francoacg.com>"]
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
termion = "1.5.6"

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src/README.md Normal file
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```
dd if=pkmn-yellow-en.gb of=surprise.pkz ibs=1 skip=183637 count=244
```

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src/main.rs Normal file
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use std::env;
use std::cmp;
use std::io::prelude::*;
use std::fs::File;
enum EncodingMode {
Mode1,
Mode2,
Mode3,
}
struct BitStream {
bit_index: u8,
byte_index: usize,
bytes: Vec<u8>,
last_two_bits: u8,
}
impl BitStream {
fn load_bytes_from_file(&mut self, filename: &str) {
let mut file = match File::open(&filename) {
Ok(file) => file,
Err(error) => panic!("Could not open the file! {:?}", error)
};
match file.read_to_end(&mut self.bytes) {
Ok(_) => println!("File data loaded!"),
Err(_) => panic!("An error ocurred trying to read the file"),
};
}
fn next_bit(&mut self) {
self.bit_index += 1;
self.check_end_of_byte();
self.update_last_two_bits();
}
fn current_byte(&self) -> u8 {
match self.bytes.get(self.byte_index) {
Some(byte) => *byte,
None => 0,
}
}
fn current_bit(&self) -> u8 {
(self.current_byte() >> 7 - self.bit_index) & 0b00000001
}
fn update_last_two_bits(&mut self) {
self.last_two_bits = ((self.last_two_bits << 1) | self.current_bit()) & 0b00000011;
}
fn check_end_of_byte(&mut self) {
let last_byte_index = self.bytes.len() - 1;
if self.byte_index >= last_byte_index {
self.byte_index = last_byte_index;
if self.bit_index >= 7 {
self.bit_index = 7;
}
} else {
if self.bit_index > 7 {
self.bit_index = 0;
self.byte_index += 1;
if self.byte_index > last_byte_index {
self.byte_index = last_byte_index;
}
}
}
}
fn read_bits(&mut self, bits_amount: u8, write_from_left: bool) -> u8 {
let mut count: u8 = 0;
let mut byte: u8 = 0;
while count < bits_amount {
byte = match write_from_left {
true => byte | (self.current_bit() << 7 - count),
false => (byte << 1) | self.current_bit(),
};
count += 1;
self.update_last_two_bits();
self.next_bit();
}
byte
}
fn bits_left(&self) -> usize {
(self.bytes.len() * 8) - ((self.byte_index * 8) + 1 + self.bit_index as usize) as usize
}
}
struct Buffer {
bit_index: u8,
width: u8,
height: u8,
vertical_offset: u8,
horizontal_offset: u8,
byte_index: usize,
bytes: Vec<u8>,
bitplane_length: usize,
row_index: usize,
}
impl Buffer {
fn allocate_space(&mut self, width: u8, height: u8) {
const MAX_SPRITE_SIZE: u8 = 7; // 7 tiles
self.width = width;
self.height = height;
// We will need the vertical and horizontal offsets later, this is used to center the resulting
// sprite in a box of 7 * 7 tiles
// vertical offset = 7 - height
// horizontal offset = ((7 - width) / 2) + (1/2) -> then round the result down
self.vertical_offset = MAX_SPRITE_SIZE - width;
self.horizontal_offset = ((MAX_SPRITE_SIZE - height) / 2) + (1 / 2);
// We need 3 bitplanes, the first and second ones are where the
// decompressed bytes will be, which are 7 x 7 each.
// The third one is usually 7 x 7 maximum too, but glitched pokemon could
// have way more
// Note: Each tile has 64 pixels
self.bitplane_length = ((7 * 7 * 2) + cmp::max(7 * 7, width as usize * height as usize)) * 8;
self.bytes = vec![0; self.bitplane_length];
}
fn write_pair(&mut self, data: u8) {
let column_height = self.height * 8;
self.bytes[self.byte_index] = self.bytes[self.byte_index] | (data << 8 - (self.bit_index + 2));
self.byte_index += 1;
self.row_index += 1;
// We have reached the end of the column
if self.row_index >= column_height as usize {
self.row_index = 0;
self.bit_index += 2;// Next column (in bits)
self.byte_index -= column_height as usize;
if self.bit_index >= 7 {
self.bit_index = 0;
// Jump to the next column
self.byte_index += column_height as usize;
}
}
}
fn write_zero_pairs(&mut self, zero_pairs_amount: usize) {
let mut count = 0;
while count < zero_pairs_amount {
self.write_pair(0);
count += 1;
}
}
fn decompress_to_bitplane(&mut self, bytes: &mut BitStream, initial_packet: u8, primary_buffer: bool, first_bitplane: bool) {
let mut rle_length: u8 = 0;
let mut reading_first_rle = initial_packet == 0; // 1 for data packet and 0 for RLE packet
let mut reading_second_rle = false;
let mut first_rle_bits_read: u16 = 0;
let mut bits_written: usize = 0;
let bytes_to_write: usize = self.width as usize * self.height as usize * 8;
// If the primary buffer is true, start decoding into buffer B at location 392,
// else, decode into buffer C at location 784
// Glitched pokemons overflow from Buffer B to C
self.byte_index = if primary_buffer {7 * 7 * 8} else {7 * 7 * 8 * 2};
self.bit_index = 0;
self.row_index = 0;
println!("Bytes to write: {}", bytes_to_write);
while (first_bitplane && bits_written < bytes_to_write * 8) || (!first_bitplane && bytes.bits_left() > 0) {
if reading_first_rle {
let current_bit = bytes.current_bit();
rle_length += 1; // We have to count the length of the rle packet even if the bit is zero
if current_bit == 0 {
// Once we find a zero, we can start reading the amount of bits we counted
// If the bit is 1, we increment the count by 1 and jump to the next bit
first_rle_bits_read = (first_rle_bits_read << 1) | (current_bit as u16);
reading_first_rle = false;
reading_second_rle = true;
} else {
// If the bit is 1, we increment the count by 1 and jump to the next bit
first_rle_bits_read = (first_rle_bits_read << 1) | (current_bit as u16);
}
bytes.next_bit();
continue;
}
if reading_second_rle {
// Read the amount of bits we counted
let mut second_rle_bits_read = 0;
let mut rle_bits_count = 0;
while rle_bits_count < rle_length {
let current_bit = bytes.current_bit();
second_rle_bits_read = (second_rle_bits_read << 1) | (current_bit as u16);
rle_bits_count += 1;
bytes.next_bit();
}
// Then, we add the first 2 groups plus one (the plus one is to take care of
// the "offset" of the compression algorithm)
// This is the amount to zero pairs that we have to add to the buffer.
// For example, if the result is 4, we will have to add 4 zero pairs,
// or 8 zeros in total
let zero_pairs = first_rle_bits_read + second_rle_bits_read + 1;
self.write_zero_pairs(zero_pairs as usize); // write the zero pairs to the buffer
bits_written += zero_pairs as usize * 2;
first_rle_bits_read = 0;
rle_length = 0;
// Aftrer reading RLE packets, the next is a data packet until we find a 00 pair
reading_first_rle = false;
reading_second_rle = false;
continue;
}
// When we are not reading RLE packets, we can read the pairs of data (data packets) until
// we find a 00 pair
if !reading_first_rle && !reading_second_rle {
let bits_pair = bytes.read_bits(2, false);
if bits_pair == 0 {
rle_length = 0;
reading_first_rle = true;
reading_second_rle = false;
} else {
self.write_pair(bits_pair); // write the zero pairs to the buffer
bits_written += 2;
}
}
}
println!("Bytes written: {}", bits_written / 8);
}
fn delta_decode(&mut self, buffer: u8) {
let index_offset = match buffer{
0 => 0, // Address at 0
1 => 7 * 7 * 8, // Address at 392
_ => 7 * 7 * 8 * 2, // Address at 784
};
let mut row_index: usize = 0;
let row_height = self.height as usize * 8; // Height in bits
let col_width = self.width as usize; // Width in bytes
// The initial state is always zero at the beginning of each row
let delta_decode_nibble: [u8; 16] = [
0b0000, 0b0001, 0b0011, 0b0010,
0b0111, 0b0110, 0b0100, 0b0101,
0b1111, 0b1110, 0b1100, 0b1101,
0b1000, 0b1001, 0b1011, 0b1010,
];
// We have to process row by row, then pairs of 4 bits for each column
while row_index < row_height {
let mut prev_state = 0;
let mut col_index: usize = 0;
while col_index < col_width {
// Calculate the index in the bytes
let index: usize = (col_index * (self.height as usize * 8) + row_index) + index_offset;
let byte = self.bytes[index];
// Getting the first sub-column (4 bits)
let first = delta_decode_nibble[(byte >> 4) as usize] ^ (0b1111 * prev_state);
prev_state = first & 1;
// Then the second sub-column (4 bits)
let second = delta_decode_nibble[(byte & 0b1111) as usize] ^ (0b1111 * prev_state);
prev_state = second & 1;
// Combine the two
self.bytes[index] = (first << 4) + second;
col_index += 1;
}
row_index += 1;
self.byte_index += 1;
}
}
fn xor_buffers(&mut self, buffer_index: u8, replace_buffer: u8) {
let buffer_index_offset: usize = match buffer_index {
0 => 0, // Address at 0
1 => 7 * 7 * 8, // Address at 392
_ => 7 * 7 * 8 * 2, // Address at 784
};
let replace_index_offset: usize = match replace_buffer {
0 => 0, // Address at 0
1 => 7 * 7 * 8, // Address at 392
_ => 7 * 7 * 8 * 2, // Address at 784
};
let mut row_index = 0;
let row_height = self.height as usize * 8; // Height in bits
while row_index < row_height {
self.bytes[(row_index + replace_index_offset) as usize] =
self.bytes[(row_index + replace_index_offset) as usize] ^
self.bytes[(row_index + buffer_index_offset) as usize];
row_index += 1;
}
}
fn wipe_bitplane(&mut self, bitplane: u8) {
let offset: usize = match bitplane {
0 => 0, // Address at 0
1 => 7 * 7 * 8, // Address at 392
_ => 7 * 7 * 8 * 2, // Address at 784
};
// Wipe the "to" bitplane first
let mut index = offset;
let buffer_size = 7 * 7 * 8;
while index < offset + buffer_size {
self.bytes[index] = 0;
index += 1;
}
}
fn copy_bitplane(&mut self, from: u8, to: u8) {
self.wipe_bitplane(to);
let to_bitplane_start: usize = match to {
0 => 0, // Address at 0
1 => 7 * 7 * 8, // Address at 392
_ => 7 * 7 * 8 * 2, // Address at 784
};
let from_bitplane_start: usize = match from {
0 => 0, // Address at 0
1 => 7 * 7 * 8, // Address at 392
_ => 7 * 7 * 8 * 2, // Address at 784
};
let mut from_bitplane_index = from_bitplane_start;
// Step 1: calculate the offset of the top-left corner
let mut index: usize = ((self.vertical_offset as usize * 8) + (self.horizontal_offset as usize * 8 * 7)) + to_bitplane_start;
// Step 2: copy the columns (height) of tiles
let height = self.height as usize * 8;
let mut current_column = 0;
while current_column < self.width {
let mut row_count: usize = 0;
while row_count < height {
self.bytes[index] = self.bytes[from_bitplane_index];
index += 1;
from_bitplane_index += 1;
row_count += 1;
}
// Revert the pointer back to the previous offset and add 56
// This will put the pointer to the next offset vertical offset
index -= height;
index += 56;
current_column += 1;
}
}
fn zip_buffers(&mut self) {
let mut last_index_buffer_a: usize = (7 * 7 * 8) - 1;
let mut last_index_buffer_b: usize = (7 * 7 * 8 * 2) - 1;
let mut last_index_buffer_c: usize = (7 * 7 * 8 * 3) - 1;
println!("last index A: {}", last_index_buffer_a);
println!("last index B: {}", last_index_buffer_b);
println!("last index C: {}", last_index_buffer_c);
loop {
self.bytes[last_index_buffer_c] = self.bytes[last_index_buffer_b];
last_index_buffer_c -= 1;
self.bytes[last_index_buffer_c] = self.bytes[last_index_buffer_a];
if last_index_buffer_a == 0 {
break;
}
last_index_buffer_a -= 1;
last_index_buffer_b -= 1;
last_index_buffer_c -= 1;
}
println!("Buffer C result: {:02X?}", &self.bytes[last_index_buffer_c..]);
}
fn render(&self) {
println!("{}", termion::clear::All);
let pixel_height = 7 * 8;
let buffer_b_start = 7 * 7 * 8; // 392
let mut index = buffer_b_start;
let buffer_c_end = (7 * 7 * 8 * 3) - 1; // 392
let mut pixel_row = 0;
let mut pixel_col = 0;
let mut current_row_pixel_count = 0;
let mut total_pixels_count = 0;
while index <= buffer_c_end {
let byte = self.bytes[index];
let mut shift: u8 = 8;
let mut count = 0;
while count < 4 {
shift -= 2;
let bit_pair = (byte >> shift) & 0b00000011;
count += 1;
let coords = termion::cursor::Goto(pixel_col + 1, pixel_row + 1);
match bit_pair {
0 => print!("{goto}{color} ", goto = coords, color = termion::color::Bg(termion::color::White)),
1 => print!("{goto}{color} ", goto = coords, color = termion::color::Bg(termion::color::Blue)),
2 => print!("{goto}{color} ", goto = coords, color = termion::color::Bg(termion::color::LightBlue)),
_ => print!("{goto}{color} ", goto = coords, color = termion::color::Bg(termion::color::Black)),
}
/* match bit_pair {
0 => print!("{goto}0", goto = coords),
2 => print!("{goto}1", goto = coords),
3 => print!("{goto}2", goto = coords),
_ => print!("{goto}3", goto = coords),
} */
total_pixels_count += 1;
pixel_col += 1;
current_row_pixel_count += 1;
if current_row_pixel_count > 7 {
current_row_pixel_count = 0;
pixel_col -= 8;
pixel_row += 1;
if pixel_row > pixel_height {
pixel_col += 8;
pixel_row = 0;
}
}
}
index += 1;
}
println!("{reset}", reset = termion::style::Reset);
println!("Total pixels count: {}", total_pixels_count);
}
fn render_all_buffers(&self) {
println!("{}", termion::clear::All);
let pixel_height = 7 * 8;
let mut pixel_row = 0;
let mut pixel_col = 0;
let mut current_row_pixel_count = 0;
let mut total_pixels_count = 0;
for byte in &self.bytes[..] {
let mut shift: u8 = 8;
let mut count = 0;
while count < 4 {
shift -= 2;
let bit_pair = (byte >> shift) & 0b00000011;
count += 1;
let coords = termion::cursor::Goto(pixel_col + 1, pixel_row + 1);
match bit_pair {
0 => print!("{goto}{color} ", goto = coords, color = termion::color::Bg(termion::color::White)),
_ => print!("{goto}{color} ", goto = coords, color = termion::color::Bg(termion::color::Black)),
}
total_pixels_count += 1;
pixel_col += 1;
current_row_pixel_count += 1;
if current_row_pixel_count > 7 {
current_row_pixel_count = 0;
pixel_col -= 8;
pixel_row += 1;
if pixel_row > pixel_height {
pixel_col += 8;
pixel_row = 0;
}
}
}
}
println!("{reset}", reset = termion::style::Reset);
println!("Total pixels count: {}", total_pixels_count);
}
}
fn main() {
// Get the filename
let args: Vec<String> = env::args().collect();
let filename = match &args.get(1) {
Some(filename) => filename.clone(),
None => panic!("No filename specified!"),
// None => "surprise.pkz",
};
println!("Filename: {}", &filename);
let mut sprite_bytes = BitStream {
bit_index: 0,
byte_index: 0,
last_two_bits: 0,
bytes: Vec::new(),
};
sprite_bytes.load_bytes_from_file(&filename);
println!("{:02X?}", sprite_bytes.bytes);
// Read the first byte:
// The first 4 bits are for the sprite width and the second 4 bits for the height
let sprite_width: u8 = sprite_bytes.read_bits(4, false); // Read next 4 bits
let sprite_height: u8 = sprite_bytes.read_bits(4, false); // Read next 4 bits
// Width the width and height we can allocate the buffer
let mut buffer = Buffer {
bit_index: 0,
byte_index: 0,
width: 0,
height: 0,
vertical_offset: 0,
horizontal_offset: 0,
bytes: Vec::new(),
bitplane_length: 0,
row_index: 0,
};
buffer.allocate_space(sprite_width, sprite_height);
println!("Sprite width: {}", buffer.width);
println!("Sprite height: {}", buffer.height);
println!("Vertical offset: {}", buffer.vertical_offset);
println!("Horizontal offset: {}", buffer.horizontal_offset);
// Primary buffer: this defines which bit buffer should be processed first
let primary_buffer: u8 = sprite_bytes.read_bits(1, false); // Read next 1 bit
println!("Primary buffer: {}", primary_buffer);
// Initial packet type of the data
// 0 means RLE packet and 1 means data packet
let initial_packet: u8 = sprite_bytes.read_bits(1, false); // Read next 1 bit
println!("Initial packet: {}", initial_packet);
println!("Total bitplane length: {}", buffer.bitplane_length * 8);
println!("Starting to decompress the first buffer!");
buffer.decompress_to_bitplane(&mut sprite_bytes, initial_packet, primary_buffer == 0, true);
println!("{:02X?}", buffer.bytes);
let encoding_mode: EncodingMode = {
if sprite_bytes.current_bit() == 0 {
sprite_bytes.next_bit();
println!("Encoding mode 1");
EncodingMode::Mode1
} else {
sprite_bytes.next_bit();
match sprite_bytes.current_bit() {
0 => {
println!("Encoding mode 2");
EncodingMode::Mode2
},
_ => {
println!("Encoding mode 3");
EncodingMode::Mode3
},
}
}
};
sprite_bytes.next_bit();
println!("Starting to decompress the second buffer!");
let initial_packet: u8 = sprite_bytes.read_bits(1, false); // Read next 1 bit
buffer.decompress_to_bitplane(&mut sprite_bytes, initial_packet, primary_buffer == 1, false);
println!("{:02X?}", buffer.bytes);
// In mode 1 and 3, we have to delta-decode the buffer C
// In any mode, we have to delta-decode the buffer B
// In mode 2 and 3, xor buffer C against buffer B
match encoding_mode {
EncodingMode::Mode1 => {
buffer.delta_decode(2);
buffer.delta_decode(1);
},
EncodingMode::Mode2 => {
buffer.delta_decode(1);
buffer.xor_buffers(1, 2);
},
EncodingMode::Mode3 => {
buffer.delta_decode(2);
buffer.xor_buffers(1, 2);
},
}
println!("Encoding result:");
println!("{:02X?}", buffer.bytes);
// Now we need to copy the content from buffer B to A and from C to B,
// but in the right order for the Gameboy to draw
buffer.copy_bitplane(1, 0);
buffer.copy_bitplane(2, 1);
println!("Bitplane copy result:");
println!("{:02X?}", buffer.bytes);
// Almost there!
// Now we need to zipper the buffer A and B into buffer C and B going backwards
buffer.zip_buffers();
println!("Resulting zip:");
println!("{:02X?}", buffer.bytes);
// And we can finally start rendering our sprite!!!
buffer.render();
}