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#[cfg(test)] extern crate rand;
#[cfg(test)] extern crate pretty_assertions;
extern crate byteorder;
use byteorder::{ReadBytesExt, WriteBytesExt, BE};
use std::io::Cursor;
use std::io::SeekFrom;
use std::io::prelude::*;
use std::iter::FromIterator;
pub fn get_subvector(base: &Vec<u8>, from: usize, till: usize) -> Vec<u8> {
if from >= till {
return vec![];
} else if from > base.len() {
return vec![];
} else if till > base.len() {
return vec![];
}
Vec::from_iter(base[from..till].iter().cloned())
}
#[cfg(test)]
mod tests {
#[test]
fn test_get_subvector() {
let ret = super::get_subvector(&vec![1, 2, 3, 4, 5, 6, 7, 8, 9], 3, 7);
assert_eq!(ret, [4, 5, 6, 7]);
}
#[test]
fn test_compress() {
use rand::{thread_rng, Rng};
let mut rng = thread_rng();
for i in 0..9 {
let mut block: Vec<u8> = Vec::new();
while block.len() != 2048 {
block.push(rng.gen_range(0, 255));
}
super::compress(block, i);
}
}
}
fn compression_search(buffer: &Vec<u8>, pos: usize, max_len: usize, search_range: usize, src_end: usize) -> (usize, usize) {
let mut found_len = 1;
let mut found = 0;
if pos + 2 < src_end {
let mut search: isize = pos as isize - search_range as isize;
if search < 0 {
search = 0;
}
let mut cmp_end = pos + max_len;
if cmp_end > src_end {
cmp_end = src_end;
}
let c1 = get_subvector(&buffer, pos, pos+1);
while search < pos as isize {
search = { let mut result: isize = -1;
for i in search..pos as isize{
if c1 == get_subvector(&buffer, i as usize, c1.len()) {
result = i as isize;
break;
}
}
result
};
if search == -1 {
break;
}
let mut cmp1 = (search + 1) as usize;
let mut cmp2 = pos + 1;
while cmp2 < cmp_end && buffer[cmp1] == buffer[cmp2] {
cmp1 += 1;
cmp2 += 1;
}
let len_ = cmp2 - pos;
if found_len < len_ {
found_len = len_;
found = search as usize;
if found_len == max_len {
break;
}
}
search += 1
}
}
(found, found_len)
}
pub fn compress(buffer: Vec<u8>, level: usize) -> Vec<u8> {
let mut result: Vec<u8> = Vec::new();
let search_range = {
if level == 0 {
0
} else if level < 9 {
0x10E0 * level / 9 - 0x0E0
} else {
0x1000
}
};
let src_end = buffer.len();
let max_len = 0x111;
let mut code_byte_pos;
let mut pos = 0;
while pos < src_end {
code_byte_pos = result.len();
result.push(0);
for i in 0..8 {
if pos >= src_end {
break;
}
let mut found_len = 1;
let mut found = 0;
if search_range > 0 {
let ret = compression_search(
&buffer, pos, max_len, search_range, src_end
);
found = ret.0;
found_len = ret.1;
}
if found_len > 2 {
let delta = pos - found - 1;
if found_len < 0x12 {
result.push((delta >> 8 | (found_len - 2) << 4) as u8);
result.push((delta & 0xFF) as u8);
} else {
result.push((delta >> 8) as u8);
result.push((delta & 0xFF) as u8);
result.push(((found_len - 0x12) & 0xFF) as u8);
}
pos += found_len;
} else {
result[code_byte_pos] |= 1 << (7 - i);
result.push(buffer[pos]);
pos += 1;
}
}
}
result
}
pub fn deflate(buffer: Vec<u8>, level: usize) -> Vec<u8> {
compress(buffer, level)
}
pub fn inflate(buffer: Vec<u8>) -> Vec<u8> {
decompress(buffer)
}
pub fn generate_header(size: u32) -> Vec<u8> { let mut result: Vec<u8> = b"Yaz0".to_vec();
result.write_u32::<BE>(size).unwrap();
result.append(&mut [0u8; 8].to_vec());
result
}
fn get_size(buffer: &Vec<u8>) -> usize {
let mut rdr = Cursor::new(buffer);
rdr.seek(SeekFrom::Start(4)).unwrap();
rdr.read_u32::<BE>().unwrap() as usize
}
pub fn decompress(buffer: Vec<u8>) -> Vec<u8> {
let size = get_size(&buffer);
let mut result: Vec<u8> = Vec::with_capacity(size);
let mut cursor = 16; let mut rcursor = 0; let mut code = buffer[cursor]; cursor += 1; let mut used_bits = 0;
while rcursor < size {
if used_bits == 8 {
code = buffer[cursor]; cursor += 1;
used_bits = 0;
}
if 0x80 & code != 0 {
result.push(buffer[cursor]); rcursor += 1;
cursor += 1;
} else {
let mut byte_count = buffer[cursor] as usize; cursor += 1;
let b2 = buffer[cursor] as usize; cursor += 1;
let mut copy_source = rcursor - ((byte_count & 0x0F) << 8 | b2) - 1;
if byte_count >> 4 == 0 {
byte_count = (buffer[cursor] as usize) + 0x12; cursor += 1;
} else {
byte_count = (byte_count >> 4) + 2;
}
for _ in 0..byte_count {
result.push(result[copy_source]);
copy_source += 1;
rcursor += 1;
}
}
code <<= 1;
used_bits += 1;
}
result
}
pub fn alt_decompress(buffer: Vec<u8>) -> Vec<u8> {
let mut result: Vec<u8> = Vec::new();
let src_end: usize = buffer.len();
let dest_end: usize = {
let mut rdr = Cursor::new(get_subvector(&buffer, 4, 8));
rdr.read_u32::<BE>().unwrap() as usize
};
while result.len() != dest_end {
result.push(0);
}
let mut code = buffer[16];
let mut src_pos: usize = 17;
let mut dest_pos: usize = 0;
while src_pos < src_end && dest_pos < dest_end {
let mut normal_exit: bool = true;
for _ in 0..8 {
if src_pos >= src_end || dest_pos >= dest_end {
normal_exit = false;
break;
}
if code & 0x80 > 0 {
result[dest_pos] = buffer[src_pos];
dest_pos += 1;
src_pos += 1;
} else {
let b1 = buffer[src_pos] as usize; src_pos += 1;
let b2 = buffer[src_pos] as usize; src_pos += 1;
let mut copy_src: usize = {
dest_pos - ((b1 & 0x0F) << 8 | b2) - 1
};
let n = {
if b1 >> 4 == 0 {
let temp: usize = (buffer[src_pos] as usize) + 0x12;
src_pos += 1;
temp
} else {
((b1 >> 4) + 2) as usize
}
};
for _ in 0..n {
result[dest_pos] = result[copy_src];
dest_pos += 1;
copy_src += 1;
}
}
code <<= 1;
}
if normal_exit {
if src_pos >= src_end || dest_pos >= dest_end {
break;
}
code = buffer[src_pos];
src_pos += 1;
}
}
result
}