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use std::u16;
use lzvalue::LZValue;
use huffman_table::{NUM_LITERALS_AND_LENGTHS, NUM_DISTANCE_CODES, END_OF_BLOCK_POSITION,
get_distance_code, get_length_code};
pub type FrequencyType = u16;
pub const MAX_BUFFER_LENGTH: usize = 1024 * 31;
#[derive(Debug, PartialEq)]
pub enum BufferStatus {
NotFull,
Full,
}
pub trait OutputWriter {
fn write_literal(&mut self, literal: u8) -> BufferStatus;
fn write_length_distance(&mut self, length: u16, distance: u16) -> BufferStatus;
fn buffer_length(&self) -> usize;
fn clear_buffer(&mut self);
fn get_buffer(&self) -> &[LZValue];
}
pub struct _DummyWriter {
written: usize,
}
impl OutputWriter for _DummyWriter {
fn write_literal(&mut self, _: u8) -> BufferStatus {
self.written += 1;
BufferStatus::NotFull
}
fn write_length_distance(&mut self, _: u16, _: u16) -> BufferStatus {
self.written += 2;
BufferStatus::NotFull
}
fn buffer_length(&self) -> usize {
self.written
}
fn clear_buffer(&mut self) {}
fn get_buffer(&self) -> &[LZValue] {
&[]
}
}
fn check_buffer_length(buffer: &[LZValue]) -> BufferStatus {
if buffer.len() >= MAX_BUFFER_LENGTH {
BufferStatus::Full
} else {
BufferStatus::NotFull
}
}
#[derive(Debug)]
pub struct FixedWriter {
pub buffer: Vec<LZValue>,
}
impl FixedWriter {
pub fn new() -> FixedWriter {
FixedWriter { buffer: Vec::with_capacity(MAX_BUFFER_LENGTH) }
}
}
impl OutputWriter for FixedWriter {
fn write_literal(&mut self, literal: u8) -> BufferStatus {
debug_assert!(self.buffer.len() < MAX_BUFFER_LENGTH);
self.buffer.push(LZValue::literal(literal));
check_buffer_length(&self.buffer)
}
fn write_length_distance(&mut self, length: u16, distance: u16) -> BufferStatus {
debug_assert!(self.buffer.len() < MAX_BUFFER_LENGTH);
self.buffer.push(LZValue::length_distance(length, distance));
check_buffer_length(&self.buffer)
}
fn buffer_length(&self) -> usize {
self.buffer.len()
}
fn clear_buffer(&mut self) {
self.buffer.clear();
}
fn get_buffer(&self) -> &[LZValue] {
&self.buffer
}
}
pub struct DynamicWriter {
fixed_writer: FixedWriter,
frequencies: [FrequencyType; NUM_LITERALS_AND_LENGTHS],
distance_frequencies: [FrequencyType; NUM_DISTANCE_CODES],
}
impl OutputWriter for DynamicWriter {
fn write_literal(&mut self, literal: u8) -> BufferStatus {
let ret = self.fixed_writer.write_literal(literal);
self.frequencies[usize::from(literal)] += 1;
ret
}
fn write_length_distance(&mut self, length: u16, distance: u16) -> BufferStatus {
let ret = self.fixed_writer.write_length_distance(length, distance);
let l_code_num = get_length_code(length);
self.frequencies[l_code_num] += 1;
let d_code_num = get_distance_code(distance);
self.distance_frequencies[usize::from(d_code_num)] += 1;
ret
}
fn buffer_length(&self) -> usize {
self.fixed_writer.buffer_length()
}
fn clear_buffer(&mut self) {
self.clear_data();
self.clear();
}
fn get_buffer(&self) -> &[LZValue] {
self.fixed_writer.get_buffer()
}
}
impl DynamicWriter {
pub fn new() -> DynamicWriter {
let mut w = DynamicWriter {
fixed_writer: FixedWriter::new(),
frequencies: [0; NUM_LITERALS_AND_LENGTHS],
distance_frequencies: [0; NUM_DISTANCE_CODES],
};
w.frequencies[END_OF_BLOCK_POSITION] = 1;
w
}
pub fn write_length_rle(&mut self, length: u16) -> BufferStatus {
let ret = self.fixed_writer.write_length_distance(length, 1);
let l_code_num = get_length_code(length);
self.frequencies[l_code_num] += 1;
self.distance_frequencies[0] += 1;
ret
}
pub fn get_frequencies(&self) -> (&[u16], &[u16]) {
(&self.frequencies, &self.distance_frequencies)
}
pub fn clear_frequencies(&mut self) {
self.frequencies = [0; NUM_LITERALS_AND_LENGTHS];
self.distance_frequencies = [0; NUM_DISTANCE_CODES];
self.frequencies[END_OF_BLOCK_POSITION] = 1;
}
pub fn clear_data(&mut self) {
self.fixed_writer.clear_buffer();
}
pub fn clear(&mut self) {
self.clear_frequencies();
self.clear_data();
}
}