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implement encoding options

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This commit is contained in:
Dennis Ranke
2022-09-24 20:52:39 +02:00
parent ced6cc8c32
commit 23872b3222
6 changed files with 87 additions and 54 deletions
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56
src/lz.rs
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@@ -1,5 +1,6 @@
use crate::context_state::ContextState;
use crate::rans::{EntropyCoder, RansDecoder};
use crate::Config;
#[derive(Copy, Clone, Debug)]
pub enum Op {
@@ -8,11 +9,11 @@ pub enum Op {
}
impl Op {
pub fn encode(&self, coder: &mut dyn EntropyCoder, state: &mut CoderState) {
pub fn encode(&self, coder: &mut dyn EntropyCoder, state: &mut CoderState, config: &Config) {
let literal_base = state.pos % state.parity_contexts * 256;
match self {
&Op::Literal(lit) => {
encode_bit(coder, state, literal_base, false);
encode_bit(coder, state, literal_base, !config.is_match_bit);
let mut context_index = 1;
for i in (0..8).rev() {
let bit = (lit >> i) & 1 != 0;
@@ -23,22 +24,28 @@ impl Op {
state.pos += 1;
}
&Op::Match { offset, len } => {
encode_bit(coder, state, literal_base, true);
encode_bit(coder, state, literal_base, config.is_match_bit);
if !state.prev_was_match {
encode_bit(
coder,
state,
256 * state.parity_contexts,
offset != state.last_offset,
(offset != state.last_offset) == config.new_offset_bit,
);
} else {
assert!(offset != state.last_offset);
}
if offset != state.last_offset {
encode_length(coder, state, 256 * state.parity_contexts + 1, offset + 1);
encode_length(
coder,
state,
256 * state.parity_contexts + 1,
offset + 1,
config,
);
state.last_offset = offset;
}
encode_length(coder, state, 256 * state.parity_contexts + 65, len);
encode_length(coder, state, 256 * state.parity_contexts + 65, len, config);
state.prev_was_match = true;
state.pos += len as usize;
}
@@ -46,12 +53,22 @@ impl Op {
}
}
pub fn encode_eof(coder: &mut dyn EntropyCoder, state: &mut CoderState) {
encode_bit(coder, state, state.pos % state.parity_contexts * 256, true);
pub fn encode_eof(coder: &mut dyn EntropyCoder, state: &mut CoderState, config: &Config) {
encode_bit(
coder,
state,
state.pos % state.parity_contexts * 256,
config.is_match_bit,
);
if !state.prev_was_match {
encode_bit(coder, state, 256 * state.parity_contexts, true);
encode_bit(
coder,
state,
256 * state.parity_contexts,
config.new_offset_bit,
);
}
encode_length(coder, state, 256 * state.parity_contexts + 1, 1);
encode_length(coder, state, 256 * state.parity_contexts + 1, 1, config);
}
fn encode_bit(
@@ -68,17 +85,18 @@ fn encode_length(
state: &mut CoderState,
context_start: usize,
mut value: u32,
config: &Config,
) {
assert!(value >= 1);
let mut context_index = context_start;
while value >= 2 {
encode_bit(coder, state, context_index, true);
encode_bit(coder, state, context_index, config.continue_value_bit);
encode_bit(coder, state, context_index + 1, value & 1 != 0);
context_index += 2;
value >>= 1;
}
encode_bit(coder, state, context_index, false);
encode_bit(coder, state, context_index, !config.continue_value_bit);
}
#[derive(Clone)]
@@ -106,7 +124,7 @@ impl CoderState {
}
}
pub fn unpack(packed_data: &[u8], config: crate::Config) -> Vec<u8> {
pub fn unpack(packed_data: &[u8], config: Config) -> Vec<u8> {
let mut decoder = RansDecoder::new(packed_data, config.use_bitstream);
let mut contexts = ContextState::new((1 + 255) * config.parity_contexts + 1 + 64 + 64);
let mut result = vec![];
@@ -117,10 +135,13 @@ pub fn unpack(packed_data: &[u8], config: crate::Config) -> Vec<u8> {
decoder: &mut RansDecoder,
contexts: &mut ContextState,
mut context_index: usize,
config: &Config,
) -> usize {
let mut length = 0;
let mut bit_pos = 0;
while decoder.decode_with_context(&mut contexts.context_mut(context_index)) {
while decoder.decode_with_context(&mut contexts.context_mut(context_index))
== config.continue_value_bit
{
length |= (decoder.decode_with_context(&mut contexts.context_mut(context_index + 1))
as usize)
<< bit_pos;
@@ -132,15 +153,19 @@ pub fn unpack(packed_data: &[u8], config: crate::Config) -> Vec<u8> {
loop {
let literal_base = result.len() % config.parity_contexts * 256;
if decoder.decode_with_context(&mut contexts.context_mut(literal_base)) {
if decoder.decode_with_context(&mut contexts.context_mut(literal_base))
== config.is_match_bit
{
if prev_was_match
|| decoder
.decode_with_context(&mut contexts.context_mut(256 * config.parity_contexts))
== config.new_offset_bit
{
offset = decode_length(
&mut decoder,
&mut contexts,
256 * config.parity_contexts + 1,
&config,
) - 1;
if offset == 0 {
break;
@@ -150,6 +175,7 @@ pub fn unpack(packed_data: &[u8], config: crate::Config) -> Vec<u8> {
&mut decoder,
&mut contexts,
256 * config.parity_contexts + 65,
&config,
);
for _ in 0..length {
result.push(result[result.len() - offset]);