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add remaining encoding config options + presets for x86 and z80

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This commit is contained in:
Dennis Ranke
2022-09-24 22:00:50 +02:00
parent 23872b3222
commit 12e6f95fe8
9 changed files with 121 additions and 45 deletions
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28
src/context_state.rs
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@@ -1,4 +1,7 @@
use crate::rans::{PROB_BITS, ONE_PROB};
use crate::{
rans::{ONE_PROB, PROB_BITS},
Config,
};
const INIT_PROB: u16 = 1 << (PROB_BITS - 1);
const UPDATE_RATE: u32 = 4;
@@ -7,6 +10,8 @@ const UPDATE_ADD: u32 = 8;
#[derive(Clone)]
pub struct ContextState {
contexts: Vec<u8>,
invert_bit_encoding: bool,
simplified_prob_update: bool,
}
pub struct Context<'a> {
@@ -15,9 +20,11 @@ pub struct Context<'a> {
}
impl ContextState {
pub fn new(size: usize) -> ContextState {
pub fn new(size: usize, config: &Config) -> ContextState {
ContextState {
contexts: vec![INIT_PROB as u8; size],
invert_bit_encoding: config.invert_bit_encoding,
simplified_prob_update: config.simplified_prob_update,
}
}
@@ -33,10 +40,21 @@ impl<'a> Context<'a> {
pub fn update(&mut self, bit: bool) {
let old = self.state.contexts[self.index];
self.state.contexts[self.index] = if bit {
old + ((ONE_PROB - old as u32 + UPDATE_ADD) >> UPDATE_RATE) as u8
self.state.contexts[self.index] = if self.state.simplified_prob_update {
let offset = if bit ^ self.state.invert_bit_encoding {
ONE_PROB as i32 >> UPDATE_RATE
} else {
0
};
(offset + old as i32 - ((old as i32 + UPDATE_ADD as i32) >> UPDATE_RATE)) as u8
} else {
old - ((old as u32 + UPDATE_ADD) >> UPDATE_RATE) as u8
if bit ^ self.state.invert_bit_encoding {
old + ((ONE_PROB - old as u32 + UPDATE_ADD) >> UPDATE_RATE) as u8
} else {
old - ((old as u32 + UPDATE_ADD) >> UPDATE_RATE) as u8
}
};
}
}