add DEFLATE decoder

png-branch
an 2019-03-12 03:39:09 -04:00
parent 745f32f3bd
commit bd13092188
12 changed files with 543 additions and 22 deletions

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@ -1,13 +1,14 @@
//! DEFLATE loader.
use crate::durandal::err::*;
use crate::durandal::{bit::*, err::*};
use std::cmp::Ordering;
/// Loads a ZLIB file header.
pub fn load_zlib_header(b: &[u8]) -> ResultS<usize>
{
const CM: u8 = 0b00001111;
const CINFO: u8 = 0b11110000;
const FDICT: u8 = 0b00100000;
const CM: u8 = 0b0000_1111;
const CINFO: u8 = 0b1111_0000;
const FDICT: u8 = 0b0010_0000;
read_data! {
2, BE in b =>
@ -33,10 +34,11 @@ pub fn load_zlib_header(b: &[u8]) -> ResultS<usize>
/// Loads a GZIP file header.
pub fn load_gzip_header(b: &[u8]) -> ResultS<usize>
{
const FHCRC: u8 = 1 << 1;
const FEXTRA: u8 = 1 << 2;
const FNAME: u8 = 1 << 3;
const FCOMMENT: u8 = 1 << 4;
const FHCRC: u8 = 1 << 1;
const FEXTRA: u8 = 1 << 2;
const FNAME: u8 = 1 << 3;
const FCOMMENT: u8 = 1 << 4;
const FRESERVED: u8 = 0xE0;
read_data! {
10, LE in b =>
@ -51,6 +53,10 @@ pub fn load_gzip_header(b: &[u8]) -> ResultS<usize>
let mut p = 10;
if fl & FRESERVED != 0 {
bail!("reserved flags set");
}
if fl & FEXTRA != 0 {
read_data!(p + 2, LE in b => xlen = u16[p] usize;);
check_data!(p + 2 + xlen, b);
@ -59,11 +65,11 @@ pub fn load_gzip_header(b: &[u8]) -> ResultS<usize>
}
if fl & FNAME != 0 {
p = skip_zero_terminated_item(&b[p..])?;
p += skip_zero_terminated_item(&b[p..])?;
}
if fl & FCOMMENT != 0 {
p = skip_zero_terminated_item(&b[p..])?;
p += skip_zero_terminated_item(&b[p..])?;
}
if fl & FHCRC != 0 {
@ -78,10 +84,315 @@ pub fn load_gzip_header(b: &[u8]) -> ResultS<usize>
fn skip_zero_terminated_item(b: &[u8]) -> ResultS<usize>
{
if let Some(i) = b.iter().position(|&n| n == 0) {
Ok(i)
Ok(i + 1)
} else {
bail!("no end of zero terminated item");
}
}
/// Decompresses a DEFLATE compressed bitstream.
pub fn load_deflate(b: &[u8]) -> ResultS<(usize, Vec<u8>)>
{
let mut v = Vec::new();
let p = stream_deflate(&mut v, b, 0)?;
Ok((p / 8, v))
}
fn stream_deflate(v: &mut Vec<u8>, b: &[u8], p: usize) -> ResultS<usize>
{
let bfinal = read_bits_l(b, p, 1)?;
let btype = read_bits_l(b, p + 1, 2)?;
let p = p + 3;
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)
}
}
fn stream_dynamic(v: &mut Vec<u8>, b: &[u8], mut p: usize) -> ResultS<usize>
{
const CODE_ORDERING: [usize; NUM_CODES] = [
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;
let hdist = read_bits_l(b, p, 5)?; p += 5;
let hclen = read_bits_l(b, p, 4)?; p += 4;
let hlit = 257 + hlit as 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];
for i in 0..hclen {
let len = read_bits_l(b, p, 3)? as u16;
p += 3;
code_lengths[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;
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");
}
}
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;
let table_len = HuffmanTable::new(&alphabet[len_sta..len_end])?;
let table_dst = HuffmanTable::new(&alphabet[dst_sta..dst_end])?;
output_tables(v, b, p, table_len, table_dst)
}
fn stream_s_table(_v: &mut Vec<u8>, _b: &[u8], _p: usize) -> ResultS<usize>
{
unimplemented!()
}
fn stream_literal(v: &mut Vec<u8>, b: &[u8], p: usize) -> ResultS<usize>
{
// copy data directly from byte boundary
let mut p = p / 8 + 1;
read_data! {
p + 4, LE in b =>
len = u16[p] usize;
}
p += 4;
v.extend_from_slice(ok!(b.get(p..p + len), "not enough data")?);
Ok((p + len) * 8)
}
fn output_tables(v: &mut Vec<u8>,
b: &[u8],
mut p: usize,
table_len: HuffmanTable,
table_dst: HuffmanTable)
-> ResultS<usize>
{
const LEN_BASE: [usize; 29] = [
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
67, 83, 99, 115, 131, 163, 195, 227, 258
];
const LEN_EXTRA_BITS: [u8; 29] = [
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4,
5, 5, 5, 5, 0
];
const DST_BASE: [usize; 30] = [
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513,
769, 1025, 1537, 2049, 3073, 4097, 0x1801, 0x2001, 0x3001, 0x4001, 0x6001
];
const DST_EXTRA_BITS: [u8; 30] = [
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10,
11, 11, 12, 12, 13, 13
];
let (bits, sym) = table_len.decode(b, p)?;
p += bits;
match sym.cmp(&256) {
Ordering::Less => {
v.push(sym as u8);
output_tables(v, b, p, table_len, table_dst)
}
Ordering::Equal => {
Ok(p)
}
Ordering::Greater => {
let sym = sym - 257;
if sym > 29 {
Err(err_msg("invalid fixed code"))
} else {
let sym = usize::from(sym);
let bits = LEN_EXTRA_BITS[sym];
let leng = LEN_BASE[sym] + read_bits_l(b, p, bits)? as usize;
p += usize::from(bits);
let (bits, sym) = table_dst.decode(b, p)?;
p += bits;
let sym = usize::from(sym);
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");
}
for _ in 0..leng {
v.push(v[v.len() - dist]);
}
output_tables(v, b, p, table_len, table_dst)
}
}
}
}
impl HuffmanTable
{
fn new(table: &[u16]) -> ResultS<Self>
{
let mut syms = vec![0; table.len()];
let mut nums = [0; 16];
// count the number of symbols for each bit length
for &length in table {
nums[usize::from(length)] += 1;
}
if usize::from(nums[0]) == table.len() {
bail!("bad table lengths");
}
// make offsets into the symbol table for each bit count
let mut ofs = [0; 16];
for i in 1..=14 {
ofs[i + 1] = ofs[i] + usize::from(nums[i]);
}
// make the actual bit pattern table
for (n, &length) in table.iter().enumerate() {
// length 0 means this code isn't used, so only try to make bit
// patterns for codes that actually exist
if length != 0 {
// make sure to make each offset unique
let offset = &mut ofs[usize::from(length)];
syms[*offset] = n as u16;
*offset += 1;
}
}
Ok(Self{nums, syms})
}
fn decode(&self, b: &[u8], mut p: usize) -> ResultS<(usize, u16)>
{
let mut code = 0_u16;
let mut first = 0_u16;
let mut index = 0_u16;
for i in 1..=15 {
// add bit from file
code |= read_bits_l(b, p, 1)? as u16;
p += 1;
// check our symbol table for this one (quick tree check)
let count = u16::from(self.nums[i]);
if i32::from(code) - i32::from(count) < i32::from(first) {
return Ok((i, self.syms[usize::from(index + code - first)]));
}
// continue on, trying to find the correct sequence
index += count;
first += count;
first <<= 1;
code <<= 1;
}
Err(err_msg("code not found in symbol tree"))
}
}
struct HuffmanTable
{
nums: [u8; 16],
syms: Vec<u16>,
}
// EOF

190
tests/data/alice.out Normal file
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@ -0,0 +1,190 @@
Alice was beginning to get very tired of sitting by her sister on the bank, and
of having nothing to do: once or twice she had peeped into the book her sister
was reading, but it had no pictures or conversations in it, 'and what is the
use of a book,' thought Alice 'without pictures or conversations?'
So she was considering in her own mind (as well as she could, for the hot day
made her feel very sleepy and stupid), whether the pleasure of making a
daisy-chain would be worth the trouble of getting up and picking the daisies,
when suddenly a White Rabbit with pink eyes ran close by her.
There was nothing so VERY remarkable in that; nor did Alice think it so VERY
much out of the way to hear the Rabbit say to itself, 'Oh dear! Oh dear! I
shall be late!' (when she thought it over afterwards, it occurred to her that
she ought to have wondered at this, but at the time it all seemed quite
natural); but when the Rabbit actually TOOK A WATCH OUT OF ITS
WAISTCOAT-POCKET, and looked at it, and then hurried on, Alice started to her
feet, for it flashed across her mind that she had never before seen a rabbit
with either a waistcoat-pocket, or a watch to take out of it, and burning with
curiosity, she ran across the field after it, and fortunately was just in time
to see it pop down a large rabbit-hole under the hedge.
In another moment down went Alice after it, never once considering how in the
world she was to get out again.
The rabbit-hole went straight on like a tunnel for some way, and then dipped
suddenly down, so suddenly that Alice had not a moment to think about stopping
herself before she found herself falling down a very deep well.
Either the well was very deep, or she fell very slowly, for she had plenty of
time as she went down to look about her and to wonder what was going to happen
next. First, she tried to look down and make out what she was coming to, but it
was too dark to see anything; then she looked at the sides of the well, and
noticed that they were filled with cupboards and book-shelves; here and there
she saw maps and pictures hung upon pegs. She took down a jar from one of the
shelves as she passed; it was labelled 'ORANGE MARMALADE', but to her great
disappointment it was empty: she did not like to drop the jar for fear of
killing somebody, so managed to put it into one of the cupboards as she fell
past it.
'Well!' thought Alice to herself, 'after such a fall as this, I shall think
nothing of tumbling down stairs! How brave they'll all think me at home! Why, I
wouldn't say anything about it, even if I fell off the top of the house!'
(Which was very likely true.)
Down, down, down. Would the fall NEVER come to an end! 'I wonder how many miles
I've fallen by this time?' she said aloud. 'I must be getting somewhere near
the centre of the earth. Let me see: that would be four thousand miles down, I
think--' (for, you see, Alice had learnt several things of this sort in her
lessons in the schoolroom, and though this was not a VERY good opportunity for
showing off her knowledge, as there was no one to listen to her, still it was
good practice to say it over) '--yes, that's about the right distance--but then
I wonder what Latitude or Longitude I've got to?' (Alice had no idea what
Latitude was, or Longitude either, but thought they were nice grand words to
say.)
Presently she began again. 'I wonder if I shall fall right THROUGH the earth!
How funny it'll seem to come out among the people that walk with their heads
downward! The Antipathies, I think--' (she was rather glad there WAS no one
listening, this time, as it didn't sound at all the right word) '--but I shall
have to ask them what the name of the country is, you know. Please, Ma'am, is
this New Zealand or Australia?' (and she tried to curtsey as she spoke--fancy
CURTSEYING as you're falling through the air! Do you think you could manage
it?) 'And what an ignorant little girl she'll think me for asking! No, it'll
never do to ask: perhaps I shall see it written up somewhere.'
Down, down, down. There was nothing else to do, so Alice soon began talking
again. 'Dinah'll miss me very much to-night, I should think!' (Dinah was the
cat.) 'I hope they'll remember her saucer of milk at tea-time. Dinah my dear! I
wish you were down here with me! There are no mice in the air, I'm afraid, but
you might catch a bat, and that's very like a mouse, you know. But do cats eat
bats, I wonder?' And here Alice began to get rather sleepy, and went on saying
to herself, in a dreamy sort of way, 'Do cats eat bats? Do cats eat bats?' and
sometimes, 'Do bats eat cats?' for, you see, as she couldn't answer either
question, it didn't much matter which way she put it. She felt that she was
dozing off, and had just begun to dream that she was walking hand in hand with
Dinah, and saying to her very earnestly, 'Now, Dinah, tell me the truth: did
you ever eat a bat?' when suddenly, thump! thump! down she came upon a heap of
sticks and dry leaves, and the fall was over.
Alice was not a bit hurt, and she jumped up on to her feet in a moment: she
looked up, but it was all dark overhead; before her was another long passage,
and the White Rabbit was still in sight, hurrying down it. There was not a
moment to be lost: away went Alice like the wind, and was just in time to hear
it say, as it turned a corner, 'Oh my ears and whiskers, how late it's
getting!' She was close behind it when she turned the corner, but the Rabbit
was no longer to be seen: she found herself in a long, low hall, which was lit
up by a row of lamps hanging from the roof.
There were doors all round the hall, but they were all locked; and when Alice
had been all the way down one side and up the other, trying every door, she
walked sadly down the middle, wondering how she was ever to get out again.
Suddenly she came upon a little three-legged table, all made of solid glass;
there was nothing on it except a tiny golden key, and Alice's first thought was
that it might belong to one of the doors of the hall; but, alas! either the
locks were too large, or the key was too small, but at any rate it would not
open any of them. However, on the second time round, she came upon a low
curtain she had not noticed before, and behind it was a little door about
fifteen inches high: she tried the little golden key in the lock, and to her
great delight it fitted!
Alice opened the door and found that it led into a small passage, not much
larger than a rat-hole: she knelt down and looked along the passage into the
loveliest garden you ever saw. How she longed to get out of that dark hall, and
wander about among those beds of bright flowers and those cool fountains, but
she could not even get her head through the doorway; 'and even if my head would
go through,' thought poor Alice, 'it would be of very little use without my
shoulders. Oh, how I wish I could shut up like a telescope! I think I could, if
I only knew how to begin.' For, you see, so many out-of-the-way things had
happened lately, that Alice had begun to think that very few things indeed were
really impossible.
There seemed to be no use in waiting by the little door, so she went back to
the table, half hoping she might find another key on it, or at any rate a book
of rules for shutting people up like telescopes: this time she found a little
bottle on it, ('which certainly was not here before,' said Alice,) and round
the neck of the bottle was a paper label, with the words 'DRINK ME' beautifully
printed on it in large letters.
It was all very well to say 'Drink me,' but the wise little Alice was not going
to do THAT in a hurry. 'No, I'll look first,' she said, 'and see whether it's
marked "poison" or not'; for she had read several nice little histories about
children who had got burnt, and eaten up by wild beasts and other unpleasant
things, all because they WOULD not remember the simple rules their friends had
taught them: such as, that a red-hot poker will burn you if you hold it too
long; and that if you cut your finger VERY deeply with a knife, it usually
bleeds; and she had never forgotten that, if you drink much from a bottle
marked 'poison,' it is almost certain to disagree with you, sooner or later.
However, this bottle was NOT marked 'poison,' so Alice ventured to taste it,
and finding it very nice, (it had, in fact, a sort of mixed flavour of
cherry-tart, custard, pine-apple, roast turkey, toffee, and hot buttered
toast,) she very soon finished it off.
* * * * * * *
* * * * * *
* * * * * * *
'What a curious feeling!' said Alice; 'I must be shutting up like a telescope.'
And so it was indeed: she was now only ten inches high, and her face brightened
up at the thought that she was now the right size for going through the little
door into that lovely garden. First, however, she waited for a few minutes to
see if she was going to shrink any further: she felt a little nervous about
this; 'for it might end, you know,' said Alice to herself, 'in my going out
altogether, like a candle. I wonder what I should be like then?' And she tried
to fancy what the flame of a candle is like after the candle is blown out, for
she could not remember ever having seen such a thing.
After a while, finding that nothing more happened, she decided on going into
the garden at once; but, alas for poor Alice! when she got to the door, she
found she had forgotten the little golden key, and when she went back to the
table for it, she found she could not possibly reach it: she could see it quite
plainly through the glass, and she tried her best to climb up one of the legs
of the table, but it was too slippery; and when she had tired herself out with
trying, the poor little thing sat down and cried.
'Come, there's no use in crying like that!' said Alice to herself, rather
sharply; 'I advise you to leave off this minute!' She generally gave herself
very good advice, (though she very seldom followed it), and sometimes she
scolded herself so severely as to bring tears into her eyes; and once she
remembered trying to box her own ears for having cheated herself in a game of
croquet she was playing against herself, for this curious child was very fond
of pretending to be two people. 'But it's no use now,' thought poor Alice, 'to
pretend to be two people! Why, there's hardly enough of me left to make ONE
respectable person!'
Soon her eye fell on a little glass box that was lying under the table: she
opened it, and found in it a very small cake, on which the words 'EAT ME' were
beautifully marked in currants. 'Well, I'll eat it,' said Alice, 'and if it
makes me grow larger, I can reach the key; and if it makes me grow smaller, I
can creep under the door; so either way I'll get into the garden, and I don't
care which happens!'
She ate a little bit, and said anxiously to herself, 'Which way? Which way?',
holding her hand on the top of her head to feel which way it was growing, and
she was quite surprised to find that she remained the same size: to be sure,
this generally happens when one eats cake, but Alice had got so much into the
way of expecting nothing but out-of-the-way things to happen, that it seemed
quite dull and stupid for life to go on in the common way.
So she set to work, and very soon finished off the cake.
* * * * * * *
* * * * * *
* * * * * * *

BIN
tests/data/alice1.in Normal file

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BIN
tests/data/alice2.in Normal file

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@ -1,13 +1,33 @@
use maraiah::marathon::defl::{self, load_gzip_header};
use maraiah::marathon::defl;
include!("data/rand.rs");
#[test]
fn defl_alice()
{
const IN_1: &[u8] = include_bytes!("data/alice1.in");
const IN_2: &[u8] = include_bytes!("data/alice2.in");
const OUT: &[u8] = include_bytes!("data/alice.out");
let p = defl::load_gzip_header(IN_1).unwrap();
assert_eq!(p, 0x14);
let b = &IN_1[p..];
assert_eq!(defl::load_deflate(b).unwrap().1, OUT.to_vec());
let p = defl::load_gzip_header(IN_2).unwrap();
assert_eq!(p, 0x14);
let b = &IN_2[p..];
assert_eq!(defl::load_deflate(b).unwrap().1, OUT.to_vec());
}
#[test]
fn defl_must_succeed()
{
assert!(load_gzip_header(include_bytes!("data/gzipok1.bin")).is_ok());
assert!(load_gzip_header(include_bytes!("data/gzipok2.bin")).is_ok());
assert!(load_gzip_header(include_bytes!("data/gzipok3.bin")).is_ok());
assert!(defl::load_gzip_header(include_bytes!("data/gzipok1.bin")).is_ok());
assert!(defl::load_gzip_header(include_bytes!("data/gzipok2.bin")).is_ok());
assert!(defl::load_gzip_header(include_bytes!("data/gzipok3.bin")).is_ok());
}
#[test]
@ -17,13 +37,13 @@ fn defl_must_not_succeed()
assert!(defl::load_gzip_header(inp).is_err());
}
assert!(load_gzip_header(include_bytes!("data/gzipbad1.bin")).is_err());
assert!(load_gzip_header(include_bytes!("data/gzipbad2.bin")).is_err());
assert!(load_gzip_header(include_bytes!("data/gzipbad3.bin")).is_err());
assert!(load_gzip_header(include_bytes!("data/gzipbad4.bin")).is_err());
assert!(load_gzip_header(include_bytes!("data/gzipbad5.bin")).is_err());
assert!(load_gzip_header(include_bytes!("data/gzipbad6.bin")).is_err());
assert!(load_gzip_header(include_bytes!("data/gzipbad7.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad1.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad2.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad3.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad4.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad5.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad6.bin")).is_err());
assert!(defl::load_gzip_header(include_bytes!("data/gzbad7.bin")).is_err());
}
// EOF