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use nihav_core::io::byteio::*;
use nihav_core::codecs::EncoderResult;
use super::super::vpcommon::*;
use super::super::vp6data::*;
use super::models::{VP6HuffModels, VP6Huff};
#[derive(Default)]
pub struct HuffState {
pub dc_zero_run: [usize; 2],
pub dc_zr_coded: [bool; 2],
pub ac_zero_run: [usize; 2],
pub ac_zr_coded: [bool; 2],
}
impl HuffState {
pub fn new() -> Self { Self::default() }
}
pub const MAX_EOB_RUN: usize = 63 + 10;
pub struct HuffEncoder<'a, 'b> {
bw: &'a mut ByteWriter<'b>,
bitbuf: u32,
bits: u8,
}
impl<'a, 'b> HuffEncoder<'a, 'b> {
pub fn new(bw: &'a mut ByteWriter<'b>) -> Self {
Self {
bitbuf: 0,
bits: 0,
bw
}
}
pub fn flush(mut self) -> EncoderResult<()> {
while self.bits > 0 {
self.bw.write_byte((self.bitbuf >> 24) as u8)?;
self.bitbuf <<= 8;
self.bits = self.bits.saturating_sub(8);
}
Ok(())
}
fn put_bits(&mut self, val: u16, bits: u8) -> EncoderResult<()> {
self.bitbuf |= u32::from(val) << (32 - self.bits - bits);
self.bits += bits;
while self.bits >= 8 {
self.bw.write_byte((self.bitbuf >> 24) as u8)?;
self.bitbuf <<= 8;
self.bits -= 8;
}
Ok(())
}
fn encode_eob(&mut self, mdl: &VP6Huff) -> EncoderResult<()> {
self.put_bits(mdl.codes[11], mdl.bits[11])
}
fn encode_val(&mut self, val: i16, mdl: &VP6Huff) -> EncoderResult<()> {
let idx = match val.abs() {
0 => 0,
1 => 1,
2 => 2,
3 => 3,
4 => 4,
5..= 6 => 5,
7..=10 => 6,
11..=18 => 7,
19..=34 => 8,
35..=66 => 9,
_ => 10,
};
self.put_bits(mdl.codes[idx], mdl.bits[idx])?;
if idx >= 5 {
self.put_bits((val.abs() - VP56_COEF_BASE[idx - 5]) as u16, VP6_COEF_ADD_BITS[idx - 5])?;
}
if idx > 0 {
self.put_bits((val < 0) as u16, 1)?;
}
Ok(())
}
fn encode_eob_run(&mut self, val: usize) -> EncoderResult<()> {
match val {
0 => { self.put_bits(0, 2)?; },
1 => { self.put_bits(1, 2)?; },
2..=5 => {
self.put_bits(2, 2)?;
self.put_bits((val - 2) as u16, 2)?;
},
6..=9 => {
self.put_bits(3, 2)?;
self.put_bits(0, 1)?;
self.put_bits((val - 6) as u16, 2)?;
},
_ => {
self.put_bits(3, 2)?;
self.put_bits(1, 1)?;
self.put_bits((val - 10) as u16, 6)?;
},
};
Ok(())
}
fn encode_zero_run(&mut self, val: usize, mdl: &VP6Huff) -> EncoderResult<()> {
self.put_bits(mdl.codes[val.min(8)], mdl.bits[val.min(8)])?;
if val >= 8 {
self.put_bits((val - 8) as u16, 6)?;
}
Ok(())
}
}
pub fn encode_block_huff(huff: &mut HuffEncoder, scan: &[usize; 64], coeffs: &[i16; 64], plane: usize, hstate: &mut HuffState, model: &VP6HuffModels) -> EncoderResult<()> {
let mut last_idx = 64;
for i in (0..64).rev() {
if coeffs[scan[i]] != 0 {
last_idx = i;
break;
}
}
if !hstate.dc_zr_coded[plane] {
let mdl = &model.dc_token_tree[plane];
huff.encode_val(coeffs[0], mdl)?;
if coeffs[0] == 0 {
huff.encode_eob_run(hstate.dc_zero_run[plane])?;
hstate.dc_zr_coded[plane] = hstate.dc_zero_run[plane] > 0;
}
} else {
hstate.dc_zero_run[plane] -= 1;
if hstate.dc_zero_run[plane] == 0 {
hstate.dc_zr_coded[plane] = false;
}
}
if hstate.ac_zr_coded[plane] {
hstate.ac_zero_run[plane] -= 1;
if hstate.ac_zero_run[plane] == 0 {
hstate.ac_zr_coded[plane] = false;
}
return Ok(());
}
let mut last_val = coeffs[0];
if last_idx == 0 || last_idx == 64 {
let ac_band = VP6_IDX_TO_AC_BAND[1].min(3);
let ac_mode = last_val.abs().min(2) as usize;
let mdl = &model.ac_token_tree[plane][ac_mode][ac_band];
huff.encode_eob(mdl)?;
huff.encode_eob_run(hstate.ac_zero_run[plane])?;
hstate.ac_zr_coded[plane] = hstate.ac_zero_run[plane] > 0;
return Ok(());
}
let mut idx = 1;
while idx < 64 {
let ac_band = VP6_IDX_TO_AC_BAND[idx].min(3);
let ac_mode = last_val.abs().min(2) as usize;
let mdl = &model.ac_token_tree[plane][ac_mode][ac_band];
if idx > last_idx {
huff.encode_eob(mdl)?;
break;
}
let val = coeffs[scan[idx]];
huff.encode_val(val, mdl)?;
idx += 1;
last_val = val;
if val == 0 {
let first_idx = idx;
while idx < 64 && coeffs[scan[idx]] == 0 {
idx += 1;
}
let zrun = idx - first_idx;
huff.encode_zero_run(zrun, &model.zero_run_tree[if first_idx >= 7 { 1 } else { 0 }])?;
}
}
Ok(())
}
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