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19cfcd2f KS |
1 | use nihav_core::io::byteio::*; |
2 | use nihav_core::codecs::{EncoderResult, EncoderError}; | |
3 | use super::models::*; | |
4 | ||
5 | pub struct EncSeq { | |
6 | pub bit: bool, | |
7 | pub idx: u8, | |
8 | } | |
9 | ||
10 | pub struct TokenSeq<T: PartialEq> { | |
11 | pub val: T, | |
12 | pub seq: &'static [EncSeq], | |
13 | } | |
14 | ||
15 | #[macro_export] | |
16 | macro_rules! bit_entry { | |
17 | (T; $idx:expr) => {EncSeq {bit: true, idx: $idx }}; | |
18 | (F; $idx:expr) => {EncSeq {bit: false, idx: $idx }}; | |
19 | } | |
20 | ||
21 | #[macro_export] | |
22 | macro_rules! bit_seq { | |
23 | ($val: expr; $( $bit:tt),* ; $( $idx:expr),* ) => { | |
24 | TokenSeq { | |
25 | val: $val, | |
26 | seq: | |
27 | &[ | |
28 | $( | |
29 | bit_entry!($bit; $idx), | |
30 | )* | |
31 | ] | |
32 | } | |
33 | }; | |
34 | } | |
35 | ||
36 | pub struct BoolEncoder<'a, 'b> { | |
37 | bw: &'a mut ByteWriter<'b>, | |
38 | val: u32, | |
39 | range: u32, | |
40 | bits: u8, | |
41 | saved: u8, | |
42 | run: usize, | |
43 | } | |
44 | ||
45 | impl<'a, 'b> BoolEncoder<'a, 'b> { | |
46 | pub fn new(bw: &'a mut ByteWriter<'b>) -> Self { | |
47 | Self { | |
48 | bw, | |
49 | val: 0, | |
50 | range: 255, | |
51 | bits: 0, | |
52 | saved: 0, | |
53 | run: 0, | |
54 | } | |
55 | } | |
56 | pub fn put_bool(&mut self, bit: bool, prob: u8) -> EncoderResult<()> { | |
57 | let split = 1 + (((self.range - 1) * u32::from(prob)) >> 8); | |
58 | if bit { | |
59 | self.range -= split; | |
60 | self.val += split; | |
61 | } else { | |
62 | self.range = split; | |
63 | } | |
64 | ||
65 | if self.range < 128 { | |
66 | self.renorm()?; | |
67 | } | |
68 | Ok(()) | |
69 | } | |
70 | fn flush_run(&mut self, overflow: bool) -> EncoderResult<()> { | |
71 | if self.run > 0 { | |
72 | self.bw.write_byte(self.saved + (overflow as u8))?; | |
73 | if !overflow { | |
74 | for _ in 1..self.run { | |
75 | self.bw.write_byte(0xFF)?; | |
76 | } | |
77 | } else { | |
78 | for _ in 1..self.run { | |
79 | self.bw.write_byte(0)?; | |
80 | } | |
81 | } | |
82 | self.run = 0; | |
83 | } | |
84 | Ok(()) | |
85 | } | |
86 | fn renorm(&mut self) -> EncoderResult<()> { | |
87 | let bits = (self.range.leading_zeros() & 7) as u8; | |
88 | self.range <<= bits; | |
89 | if self.bits + bits < 23 { | |
90 | self.bits += bits; | |
91 | self.val <<= bits; | |
92 | } else { | |
93 | for _ in 0..bits { | |
94 | if (self.bits == 23) && ((self.val >> 31) != 0) { | |
95 | self.flush_run(true)?; | |
96 | } | |
97 | self.val <<= 1; | |
98 | self.bits += 1; | |
99 | if self.bits == 24 { | |
100 | let tbyte = (self.val >> 24) as u8; | |
101 | let nbyte = (self.val >> 16) as u8; | |
102 | if tbyte < 0xFF { | |
103 | self.flush_run(false)?; | |
104 | if nbyte < 0xFE { | |
105 | self.bw.write_byte(tbyte)?; | |
106 | } else { | |
107 | self.saved = tbyte; | |
108 | self.run = 1; | |
109 | } | |
110 | } else { | |
111 | self.run += 1; | |
112 | } | |
113 | self.val &= 0xFFFFFF; | |
114 | self.bits -= 8; | |
115 | } | |
116 | } | |
117 | } | |
118 | Ok(()) | |
119 | } | |
120 | pub fn flush(mut self) -> EncoderResult<()> { | |
121 | self.flush_run(false)?; | |
122 | self.val <<= 24 - self.bits; | |
123 | self.bw.write_u32be(self.val)?; | |
124 | Ok(()) | |
125 | } | |
126 | ||
127 | pub fn put_bits(&mut self, val: u32, len: u8) -> EncoderResult<()> { | |
128 | let mut mask = 1 << (len - 1); | |
129 | while mask != 0 { | |
130 | self.put_bool((val & mask) != 0, 128)?; | |
131 | mask >>= 1; | |
132 | } | |
133 | Ok(()) | |
134 | } | |
135 | pub fn put_probability(&mut self, prob: u8) -> EncoderResult<()> { | |
136 | self.put_bits(u32::from(prob >> 1), 7) | |
137 | } | |
138 | pub fn encode_probability(&mut self, new: u8, old: u8, prob: u8) -> EncoderResult<()> { | |
139 | self.put_bool(new != old, prob)?; | |
140 | if new != old { | |
141 | self.put_probability(new)?; | |
142 | } | |
143 | Ok(()) | |
144 | } | |
145 | pub fn write_el<T: PartialEq>(&mut self, el: T, tree: &[TokenSeq<T>], probs: &[u8]) -> EncoderResult<()> { | |
146 | for entry in tree.iter() { | |
147 | if entry.val == el { | |
148 | for seq in entry.seq.iter() { | |
149 | self.put_bool(seq.bit, probs[seq.idx as usize])?; | |
150 | } | |
151 | return Ok(()); | |
152 | } | |
153 | } | |
154 | Err(EncoderError::Bug) | |
155 | } | |
156 | } | |
157 | ||
158 | pub struct Estimator {} | |
159 | ||
160 | #[allow(dead_code)] | |
161 | impl Estimator { | |
162 | pub fn new() -> Self { Self{} } | |
163 | pub fn write_el<T: PartialEq>(&self, el: T, tree: &[TokenSeq<T>], probs: &mut [ProbCounter]) { | |
164 | for entry in tree.iter() { | |
165 | if entry.val == el { | |
166 | for seq in entry.seq.iter() { | |
167 | probs[seq.idx as usize].add(seq.bit); | |
168 | } | |
169 | return; | |
170 | } | |
171 | } | |
172 | } | |
173 | pub fn est_nits(bit: bool, prob: u8) -> u32 { | |
174 | if !bit { | |
175 | u32::from(PROB_BITS[prob as usize]) | |
176 | } else { | |
177 | u32::from(PROB_BITS[256 - (prob as usize)]) | |
178 | } | |
179 | } | |
180 | pub fn nits_to_bits(nits: u32) -> u32 { (nits + 7) >> 3 } | |
181 | } |