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|
use nihav_core::io::byteio::*;
use nihav_core::codecs::{EncoderResult, EncoderError};
use super::models::*;
pub struct EncSeq {
pub bit: bool,
pub idx: u8,
}
pub struct TokenSeq<T: PartialEq> {
pub val: T,
pub seq: &'static [EncSeq],
}
#[macro_export]
macro_rules! bit_entry {
(T; $idx:expr) => {EncSeq {bit: true, idx: $idx }};
(F; $idx:expr) => {EncSeq {bit: false, idx: $idx }};
}
#[macro_export]
macro_rules! bit_seq {
($val: expr; $( $bit:tt),* ; $( $idx:expr),* ) => {
TokenSeq {
val: $val,
seq:
&[
$(
bit_entry!($bit; $idx),
)*
]
}
};
}
pub struct BoolEncoder<'a, 'b> {
bw: &'a mut ByteWriter<'b>,
val: u32,
range: u32,
bits: u8,
saved: u8,
run: usize,
}
impl<'a, 'b> BoolEncoder<'a, 'b> {
pub fn new(bw: &'a mut ByteWriter<'b>) -> Self {
Self {
bw,
val: 0,
range: 255,
bits: 0,
saved: 0,
run: 0,
}
}
pub fn put_bool(&mut self, bit: bool, prob: u8) -> EncoderResult<()> {
let split = 1 + (((self.range - 1) * u32::from(prob)) >> 8);
if bit {
self.range -= split;
self.val += split;
} else {
self.range = split;
}
if self.range < 128 {
self.renorm()?;
}
Ok(())
}
fn flush_run(&mut self, overflow: bool) -> EncoderResult<()> {
if self.run > 0 {
self.bw.write_byte(self.saved + (overflow as u8))?;
if !overflow {
for _ in 1..self.run {
self.bw.write_byte(0xFF)?;
}
} else {
for _ in 1..self.run {
self.bw.write_byte(0)?;
}
}
self.run = 0;
}
Ok(())
}
fn renorm(&mut self) -> EncoderResult<()> {
let bits = (self.range.leading_zeros() & 7) as u8;
self.range <<= bits;
if self.bits + bits < 23 {
self.bits += bits;
self.val <<= bits;
} else {
for _ in 0..bits {
if (self.bits == 23) && ((self.val >> 31) != 0) {
self.flush_run(true)?;
}
self.val <<= 1;
self.bits += 1;
if self.bits == 24 {
let tbyte = (self.val >> 24) as u8;
let nbyte = (self.val >> 16) as u8;
if tbyte < 0xFF {
self.flush_run(false)?;
if nbyte < 0xFE {
self.bw.write_byte(tbyte)?;
} else {
self.saved = tbyte;
self.run = 1;
}
} else {
self.run += 1;
}
self.val &= 0xFFFFFF;
self.bits -= 8;
}
}
}
Ok(())
}
pub fn flush(mut self) -> EncoderResult<()> {
self.flush_run(false)?;
self.val <<= 24 - self.bits;
self.bw.write_u32be(self.val)?;
Ok(())
}
pub fn put_bits(&mut self, val: u32, len: u8) -> EncoderResult<()> {
let mut mask = 1 << (len - 1);
while mask != 0 {
self.put_bool((val & mask) != 0, 128)?;
mask >>= 1;
}
Ok(())
}
pub fn put_probability(&mut self, prob: u8) -> EncoderResult<()> {
self.put_bits(u32::from(prob >> 1), 7)
}
pub fn encode_probability(&mut self, new: u8, old: u8, prob: u8) -> EncoderResult<()> {
self.put_bool(new != old, prob)?;
if new != old {
self.put_probability(new)?;
}
Ok(())
}
pub fn write_el<T: PartialEq>(&mut self, el: T, tree: &[TokenSeq<T>], probs: &[u8]) -> EncoderResult<()> {
for entry in tree.iter() {
if entry.val == el {
for seq in entry.seq.iter() {
self.put_bool(seq.bit, probs[seq.idx as usize])?;
}
return Ok(());
}
}
Err(EncoderError::Bug)
}
}
pub struct Estimator {}
#[allow(dead_code)]
impl Estimator {
pub fn new() -> Self { Self{} }
pub fn write_el<T: PartialEq>(&self, el: T, tree: &[TokenSeq<T>], probs: &mut [ProbCounter]) {
for entry in tree.iter() {
if entry.val == el {
for seq in entry.seq.iter() {
probs[seq.idx as usize].add(seq.bit);
}
return;
}
}
}
pub fn est_nits(bit: bool, prob: u8) -> u32 {
if !bit {
u32::from(PROB_BITS[prob as usize])
} else {
u32::from(PROB_BITS[256 - (prob as usize)])
}
}
pub fn nits_to_bits(nits: u32) -> u32 { (nits + 7) >> 3 }
}
|
