make deflate functions non-recursive (sad)
parent
499c25fb93
commit
0c0591f5ce
|
|
@ -94,41 +94,31 @@ fn skip_zero_terminated_item(b: &[u8]) -> ResultS<usize>
|
|||
pub fn load_deflate(b: &[u8]) -> ResultS<(usize, Vec<u8>)>
|
||||
{
|
||||
let mut v = Vec::new();
|
||||
let p = stream_deflate(&mut v, b, 0)?;
|
||||
let mut p = 0;
|
||||
|
||||
Ok((p / 8, v))
|
||||
}
|
||||
loop {
|
||||
let bfinal = read_bits_l(b, p, 1)?; p += 1;
|
||||
let btype = read_bits_l(b, p, 2)?; p += 2;
|
||||
|
||||
fn stream_deflate(v: &mut Vec<u8>, b: &[u8], mut p: usize) -> ResultS<usize>
|
||||
{
|
||||
let bfinal = read_bits_l(b, p, 1)?; p += 1;
|
||||
let btype = read_bits_l(b, p, 2)?; p += 2;
|
||||
match btype {
|
||||
0b10 => p = stream_dynamic(&mut v, b, p)?,
|
||||
0b01 => p = stream_s_table(&mut v, b, p)?,
|
||||
0b00 => p = stream_literal(&mut v, b, p)?,
|
||||
_ => bail!("bad btype"),
|
||||
}
|
||||
|
||||
let p = match btype {
|
||||
0b10 => stream_dynamic(v, b, p)?,
|
||||
0b01 => stream_s_table(v, b, p)?,
|
||||
0b00 => stream_literal(v, b, p)?,
|
||||
_ => bail!("bad btype"),
|
||||
};
|
||||
|
||||
if bfinal == 0 {
|
||||
stream_deflate(v, b, p)
|
||||
} else {
|
||||
Ok(p)
|
||||
if bfinal == 1 {
|
||||
return Ok((p / 8, v));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn stream_dynamic(v: &mut Vec<u8>, b: &[u8], mut p: usize) -> ResultS<usize>
|
||||
{
|
||||
const CODE_ORDERING: [usize; NUM_CODES] = [
|
||||
const CODE_ORDERING: [usize; 19] = [
|
||||
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
|
||||
];
|
||||
|
||||
const NUM_CODES: usize = 19;
|
||||
|
||||
const MAX_LIT_CODES: usize = 286;
|
||||
const MAX_DST_CODES: usize = 30;
|
||||
|
||||
// read header (number of literal alphabet codes, number of distance
|
||||
// alphabet codes, and number of lengths for decoding the alphabet)
|
||||
let hlit = read_bits_l(b, p, 5)?; p += 5;
|
||||
|
|
@ -139,80 +129,30 @@ fn stream_dynamic(v: &mut Vec<u8>, b: &[u8], mut p: usize) -> ResultS<usize>
|
|||
let hdist = 1 + hdist as usize;
|
||||
let hclen = 4 + hclen as usize;
|
||||
|
||||
let alphabet_total = hlit + hdist;
|
||||
|
||||
// first, get the huffman coding for the alphabet (which is also compressed)
|
||||
let mut code_lengths = [0; NUM_CODES];
|
||||
let mut code_table = [0; 19];
|
||||
|
||||
for i in 0..hclen {
|
||||
let len = read_bits_l(b, p, 3)? as u16;
|
||||
p += 3;
|
||||
|
||||
code_lengths[CODE_ORDERING[i]] = len;
|
||||
code_table[CODE_ORDERING[i]] = len;
|
||||
}
|
||||
|
||||
let code_lengths = HuffmanTable::new(&code_lengths)?;
|
||||
let mut alphabet = [0; MAX_LIT_CODES + MAX_DST_CODES];
|
||||
|
||||
// then, we decode the alphabet (doing both types at the same time, because
|
||||
// they're encoded the same anyways)
|
||||
let mut i = 0;
|
||||
while i < alphabet_total {
|
||||
let (bits, sym) = code_lengths.decode(b, p)?;
|
||||
p += bits;
|
||||
let code_table = HuffmanTable::new(&code_table)?;
|
||||
let mut alphabet = vec![0; hlit + hdist];
|
||||
|
||||
match sym {
|
||||
0..=15 => {
|
||||
// raw code
|
||||
alphabet[i] = sym;
|
||||
i += 1;
|
||||
}
|
||||
16 => {
|
||||
// copy previous code 3-6 times
|
||||
if i == 0 {bail!("cannot copy on first alphabet code");}
|
||||
|
||||
let len = usize::from(read_bits_l(b, p, 2)? as u8 + 3);
|
||||
let lst = alphabet[i - 1];
|
||||
p += 2;
|
||||
|
||||
for _ in 0..len {alphabet[i] = lst; i += 1;}
|
||||
}
|
||||
17 => {
|
||||
// repeat '0' 3-10 times
|
||||
let len = usize::from(read_bits_l(b, p, 3)? as u8 + 3);
|
||||
p += 3;
|
||||
|
||||
for _ in 0..len {alphabet[i] = 0; i += 1;}
|
||||
}
|
||||
18 => {
|
||||
// repeat '0' 11-138 times
|
||||
let len = usize::from(read_bits_l(b, p, 7)? as u8 + 11);
|
||||
p += 7;
|
||||
|
||||
for _ in 0..len {alphabet[i] = 0; i += 1;}
|
||||
}
|
||||
_ => {
|
||||
bail!("bad symbol in alphabet");
|
||||
}
|
||||
}
|
||||
|
||||
if i > alphabet_total {
|
||||
bail!("too many codes");
|
||||
}
|
||||
}
|
||||
p = read_alphabet(b, p, &mut alphabet, code_table)?;
|
||||
|
||||
if alphabet[256] == 0 {
|
||||
bail!("no way to end block");
|
||||
}
|
||||
|
||||
let len_sta = 0;
|
||||
let len_end = hlit;
|
||||
let dst_sta = len_end;
|
||||
let dst_end = dst_sta + hdist;
|
||||
|
||||
// build the length and distance tables from this information
|
||||
let table_len = HuffmanTable::new(&alphabet[len_sta..len_end])?;
|
||||
let table_dst = HuffmanTable::new(&alphabet[dst_sta..dst_end])?;
|
||||
let table_len = HuffmanTable::new(&alphabet[ 0..hlit ])?;
|
||||
let table_dst = HuffmanTable::new(&alphabet[hlit..hlit + hdist])?;
|
||||
|
||||
output_tables(v, b, p, table_len, table_dst)
|
||||
}
|
||||
|
|
@ -251,6 +191,60 @@ fn stream_literal(v: &mut Vec<u8>, b: &[u8], p: usize) -> ResultS<usize>
|
|||
Ok((p + len) * 8)
|
||||
}
|
||||
|
||||
fn read_alphabet(b: &[u8],
|
||||
mut p: usize,
|
||||
alphabet: &mut [u16],
|
||||
code_table: HuffmanTable)
|
||||
-> ResultS<usize>
|
||||
{
|
||||
let mut i = 0;
|
||||
while i < alphabet.len() {
|
||||
let (bits, sym) = code_table.decode(b, p)?;
|
||||
p += bits;
|
||||
|
||||
match sym {
|
||||
0..=15 => {
|
||||
// raw code
|
||||
alphabet[i] = sym;
|
||||
i += 1;
|
||||
}
|
||||
16 => {
|
||||
// copy previous code 3-6 times
|
||||
if i == 0 {bail!("cannot copy on first alphabet code");}
|
||||
|
||||
let len = usize::from(read_bits_l(b, p, 2)? as u8 + 3);
|
||||
let lst = alphabet[i - 1];
|
||||
p += 2;
|
||||
|
||||
for _ in 0..len {alphabet[i] = lst; i += 1;}
|
||||
}
|
||||
17 => {
|
||||
// repeat '0' 3-10 times
|
||||
let len = usize::from(read_bits_l(b, p, 3)? as u8 + 3);
|
||||
p += 3;
|
||||
|
||||
for _ in 0..len {alphabet[i] = 0; i += 1;}
|
||||
}
|
||||
18 => {
|
||||
// repeat '0' 11-138 times
|
||||
let len = usize::from(read_bits_l(b, p, 7)? as u8 + 11);
|
||||
p += 7;
|
||||
|
||||
for _ in 0..len {alphabet[i] = 0; i += 1;}
|
||||
}
|
||||
_ => {
|
||||
bail!("bad symbol in alphabet");
|
||||
}
|
||||
}
|
||||
|
||||
if i > alphabet.len() {
|
||||
bail!("too many codes");
|
||||
}
|
||||
}
|
||||
|
||||
Ok(p)
|
||||
}
|
||||
|
||||
fn output_tables(v: &mut Vec<u8>,
|
||||
b: &[u8],
|
||||
mut p: usize,
|
||||
|
|
@ -278,54 +272,53 @@ fn output_tables(v: &mut Vec<u8>,
|
|||
11, 11, 12, 12, 13, 13
|
||||
];
|
||||
|
||||
let (bits, sym) = table_len.decode(b, p)?;
|
||||
p += bits;
|
||||
loop {
|
||||
let (bits, sym) = table_len.decode(b, p)?;
|
||||
p += bits;
|
||||
|
||||
match sym.cmp(&256) {
|
||||
Ordering::Less => {
|
||||
// direct byte
|
||||
v.push(sym as u8);
|
||||
output_tables(v, b, p, table_len, table_dst)
|
||||
}
|
||||
Ordering::Equal => {
|
||||
Ok(p)
|
||||
}
|
||||
Ordering::Greater => {
|
||||
// this is a <len, dst> pair
|
||||
let sym = sym - 257;
|
||||
|
||||
if sym > 29 {
|
||||
bail!("invalid fixed code");
|
||||
match sym.cmp(&256) {
|
||||
Ordering::Less => {
|
||||
// direct byte
|
||||
v.push(sym as u8);
|
||||
}
|
||||
|
||||
let sym = usize::from(sym);
|
||||
|
||||
// first get the actual length and any extra bits it may have
|
||||
let bits = LEN_EXTRA_BITS[sym];
|
||||
let leng = LEN_BASE[sym] + read_bits_l(b, p, bits)? as usize;
|
||||
p += usize::from(bits);
|
||||
|
||||
// decode the distance with its alphabet
|
||||
let (bits, sym) = table_dst.decode(b, p)?;
|
||||
p += bits;
|
||||
|
||||
let sym = usize::from(sym);
|
||||
|
||||
// get the actual distance and any extra bits it may have
|
||||
let bits = DST_EXTRA_BITS[sym];
|
||||
let dist = DST_BASE[sym] + read_bits_l(b, p, bits)? as usize;
|
||||
p += usize::from(bits);
|
||||
|
||||
if dist > v.len() {
|
||||
bail!("bad distance");
|
||||
Ordering::Equal => {
|
||||
return Ok(p);
|
||||
}
|
||||
Ordering::Greater => {
|
||||
// this is a <len, dst> pair
|
||||
let sym = sym - 257;
|
||||
|
||||
// copy bytes from earlier
|
||||
for _ in 0..leng {
|
||||
v.push(v[v.len() - dist]);
|
||||
if sym > 29 {
|
||||
bail!("invalid fixed code");
|
||||
}
|
||||
|
||||
let sym = usize::from(sym);
|
||||
|
||||
// first get the actual length and any extra bits it may have
|
||||
let bits = LEN_EXTRA_BITS[sym];
|
||||
let leng = LEN_BASE[sym] + read_bits_l(b, p, bits)? as usize;
|
||||
p += usize::from(bits);
|
||||
|
||||
// decode the distance with its alphabet
|
||||
let (bits, sym) = table_dst.decode(b, p)?;
|
||||
p += bits;
|
||||
|
||||
let sym = usize::from(sym);
|
||||
|
||||
// get the actual distance and any extra bits it may have
|
||||
let bits = DST_EXTRA_BITS[sym];
|
||||
let dist = DST_BASE[sym] + read_bits_l(b, p, bits)? as usize;
|
||||
p += usize::from(bits);
|
||||
|
||||
if dist > v.len() {
|
||||
bail!("bad distance");
|
||||
}
|
||||
|
||||
// copy bytes from earlier
|
||||
for _ in 0..leng {
|
||||
v.push(v[v.len() - dist]);
|
||||
}
|
||||
}
|
||||
|
||||
output_tables(v, b, p, table_len, table_dst)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue