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a4bd7707 KS |
1 | //! Codebook support for bitstream reader. |
2 | //! | |
3 | //! Codebook is a set of unique bit strings and values assigned to them. | |
4 | //! Since there are many ways to define codebook, this implementation employs [`CodebookDescReader`] trait to provide codebook generator with the codes. | |
5 | //! Please also pay attention to the codebook creation mode: if bitstream reader reads bits starting from most significant bit first then you should use [`MSB`] mode and [`LSB`] mode otherwise. | |
6 | //! | |
7 | //! # Examples | |
8 | //! | |
9 | //! Create a codebook from arrays with codeword descriptions: | |
10 | //! ``` | |
11 | //! use nihav_core::io::codebook::{ShortCodebookDesc, ShortCodebookDescReader, Codebook, CodebookMode}; | |
12 | //! | |
13 | //! let cb_desc: Vec<ShortCodebookDesc> = vec!( | |
14 | //! ShortCodebookDesc { code: 0b00, bits: 2 }, | |
15 | //! ShortCodebookDesc { code: 0, bits: 0 }, | |
16 | //! ShortCodebookDesc { code: 0b01, bits: 2 }, | |
17 | //! ShortCodebookDesc { code: 0b1, bits: 1 }); | |
18 | //! let mut cr = ShortCodebookDescReader::new(cb_desc); | |
4a483ccb | 19 | //! let cb = Codebook::new(&mut cr, CodebookMode::MSB).unwrap(); |
a4bd7707 KS |
20 | //! ``` |
21 | //! | |
22 | //! Create a codebook using more flexible [`TableCodebookDescReader`] approach. | |
23 | //! This will create a codebook for the following set: `1` -> -2, `01` -> -1, `001` -> 0, `0001` -> 1, `00001` -> 2. | |
24 | //! ``` | |
25 | //! use nihav_core::io::codebook::{TableCodebookDescReader, Codebook, CodebookMode}; | |
26 | //! | |
27 | //! fn map_cb_index(index: usize) -> i16 { (index as i16) - 2 } | |
28 | //! const CB_BITS: [u8; 5] = [ 1, 2, 3, 4, 5 ]; | |
29 | //! const CB_CODES: [u8; 5] = [ 1, 1, 1, 1, 1 ]; | |
30 | //! | |
31 | //! let mut tcr = TableCodebookDescReader::new(&CB_CODES, &CB_BITS, map_cb_index); | |
32 | //! let cb = Codebook::new(&mut tcr, CodebookMode::MSB).unwrap(); | |
33 | //! ``` | |
34 | //! | |
35 | //! Read value using a codebook: | |
36 | //! ```no_run | |
37 | //! use nihav_core::io::bitreader::BitReader; | |
38 | //! use nihav_core::io::codebook::{Codebook, CodebookReader, CodebookMode}; | |
39 | //! # use nihav_core::io::codebook::{ShortCodebookDesc, ShortCodebookDescReader, CodebookDescReader, CodebookResult}; | |
40 | //! | |
41 | //! # fn foo(br: &mut BitReader) -> CodebookResult<()> { | |
42 | //! # let mut cr = ShortCodebookDescReader::new(vec![ShortCodebookDesc { code: 0b00, bits: 2 }]); | |
43 | //! let cb = Codebook::new(&mut cr, CodebookMode::MSB).unwrap(); | |
44 | //! let value = br.read_cb(&cb)?; | |
45 | //! # Ok(()) | |
46 | //! # } | |
47 | //! ``` | |
48 | //! | |
49 | //! [`MSB`]: ./enum.CodebookMode.html#variant.MSB | |
50 | //! [`LSB`]: ./enum.CodebookMode.html#variant.LSB | |
51 | //! [`CodebookDescReader`]: ./trait.CodebookDescReader.html | |
52 | //! [`TableCodebookDescReader`]: ./struct.TableCodebookDescReader.html | |
53 | ||
0ca65ffd KS |
54 | use std::collections::HashMap; |
55 | use std::cmp::{max, min}; | |
aca89041 | 56 | use super::bitreader::BitReader; |
4667915a | 57 | |
a4bd7707 | 58 | /// A list specifying general codebook operations errors. |
4667915a KS |
59 | #[derive(Debug)] |
60 | pub enum CodebookError { | |
a4bd7707 | 61 | /// Codebook description contains errors. |
4667915a | 62 | InvalidCodebook, |
a4bd7707 | 63 | /// Could not allocate memory for codebook. |
4667915a | 64 | MemoryError, |
a4bd7707 | 65 | /// Bitstream contains a sequence not present in codebook. |
4667915a KS |
66 | InvalidCode, |
67 | } | |
68 | ||
a4bd7707 | 69 | /// Codebook operation modes. |
0ca65ffd KS |
70 | #[derive(Debug, Copy, Clone)] |
71 | pub enum CodebookMode { | |
a4bd7707 | 72 | /// Codes in the codebook should be read most significant bit first. |
0ca65ffd | 73 | MSB, |
a4bd7707 | 74 | /// Codes in the codebook should be read least significant bit first. |
0ca65ffd KS |
75 | LSB, |
76 | } | |
77 | ||
a4bd7707 KS |
78 | /// A specialised `Result` type for codebook operations. |
79 | pub type CodebookResult<T> = Result<T, CodebookError>; | |
4667915a | 80 | |
a4bd7707 KS |
81 | /// Codebook description for `(code bits, code length, code value)` triplet. |
82 | /// | |
83 | /// This should be used to create a list of codeword definitions for [`FullCodebookDescReader`]. | |
84 | /// | |
85 | /// [`FullCodebookDescReader`]: ./struct.FullCodebookDescReader.html | |
fd47a9b6 | 86 | #[derive(Clone,Copy)] |
4667915a | 87 | pub struct FullCodebookDesc<S> { |
a4bd7707 | 88 | /// Codeword bits. |
9a62b981 | 89 | pub code: u32, |
a4bd7707 | 90 | /// Codeword length. |
9a62b981 | 91 | pub bits: u8, |
a4bd7707 | 92 | /// Codeword value (symbol). |
9a62b981 | 93 | pub sym: S, |
4667915a KS |
94 | } |
95 | ||
a4bd7707 KS |
96 | /// Codebook description for `(code bits, code length)` pair with array index being used as codeword value. |
97 | /// | |
98 | /// This should be used to create a list of codeword definitions for [`ShortCodebookDescReader`]. | |
99 | /// | |
100 | /// [`ShortCodebookDescReader`]: ./struct.ShortCodebookDescReader.html | |
fd47a9b6 | 101 | #[derive(Clone,Copy)] |
4667915a | 102 | pub struct ShortCodebookDesc { |
a4bd7707 | 103 | /// Codeword bits. |
9a62b981 | 104 | pub code: u32, |
a4bd7707 | 105 | /// Codeword length. |
9a62b981 | 106 | pub bits: u8, |
4667915a KS |
107 | } |
108 | ||
a4bd7707 KS |
109 | /// The interface for providing a list of codeword definitions to the codebook creator. |
110 | /// | |
111 | /// The structure implementing this trait should be able to provide the total number of defined codewords and their bits and values. [`ShortCodebookDescReader`] or [`TableCodebookDescReader`] are some examples of such implementation. | |
112 | /// Codeword definitions with zero length are ignored (those may be used to create sparse codebook definitions though). | |
113 | /// | |
114 | /// [`ShortCodebookDescReader`]: ./struct.ShortCodebookDescReader.html | |
115 | /// [`TableCodebookDescReader`]: ./struct.TableCodebookDescReader.html | |
4667915a | 116 | pub trait CodebookDescReader<S> { |
a4bd7707 | 117 | /// Returns the codeword length for the provided index. |
4667915a | 118 | fn bits(&mut self, idx: usize) -> u8; |
a4bd7707 | 119 | /// Returns the codeword bits for the provided index. |
4667915a | 120 | fn code(&mut self, idx: usize) -> u32; |
a4bd7707 | 121 | /// Returns the codeword value (aka codeword symbol) for the provided index. |
4667915a | 122 | fn sym (&mut self, idx: usize) -> S; |
a4bd7707 | 123 | /// Returns the total number of defined codewords. |
4667915a KS |
124 | fn len (&mut self) -> usize; |
125 | } | |
126 | ||
a4bd7707 | 127 | /// The codebook structure for code reading. |
4667915a KS |
128 | #[allow(dead_code)] |
129 | pub struct Codebook<S> { | |
cec9f863 KS |
130 | pub table: Vec<u32>, |
131 | pub syms: Vec<S>, | |
132 | pub lut_bits: u8, | |
4667915a KS |
133 | } |
134 | ||
a4bd7707 | 135 | /// Trait allowing bitreader to use codebook for decoding bit sequences. |
4667915a | 136 | pub trait CodebookReader<S> { |
a4bd7707 KS |
137 | /// Reads the codeword from the bitstream and returns its value (or [`InvalidCode`] on error). |
138 | /// | |
139 | /// [`InvalidCode`]: ./enum.CodebookError.html#variant.InvalidCode | |
4667915a KS |
140 | fn read_cb(&mut self, cb: &Codebook<S>) -> CodebookResult<S>; |
141 | } | |
142 | ||
cec9f863 | 143 | pub const TABLE_FILL_VALUE: u32 = 0x7F; |
0ca65ffd KS |
144 | const MAX_LUT_BITS: u8 = 10; |
145 | ||
146 | fn fill_lut_msb(table: &mut Vec<u32>, off: usize, | |
d23f3327 | 147 | code: u32, bits: u8, lut_bits: u8, symidx: u32, esc: bool) -> CodebookResult<()> { |
0ca65ffd KS |
148 | if !esc { |
149 | let fill_len = lut_bits - bits; | |
150 | let fill_size = 1 << fill_len; | |
151 | let fill_code = code << (lut_bits - bits); | |
e243ceb4 | 152 | let lut_value = (symidx << 8) | u32::from(bits); |
0ca65ffd KS |
153 | for j in 0..fill_size { |
154 | let idx = (fill_code + j) as usize; | |
d23f3327 | 155 | if table[idx + off] != TABLE_FILL_VALUE { return Err(CodebookError::InvalidCodebook); } |
0ca65ffd KS |
156 | table[idx + off] = lut_value; |
157 | } | |
158 | } else { | |
159 | let idx = (code as usize) + off; | |
d23f3327 | 160 | if table[idx] != TABLE_FILL_VALUE { return Err(CodebookError::InvalidCodebook); } |
e243ceb4 | 161 | table[idx] = (symidx << 8) | 0x80 | u32::from(bits); |
0ca65ffd | 162 | } |
d23f3327 | 163 | Ok(()) |
0ca65ffd KS |
164 | } |
165 | ||
166 | fn fill_lut_lsb(table: &mut Vec<u32>, off: usize, | |
d23f3327 | 167 | code: u32, bits: u8, lut_bits: u8, symidx: u32, esc: bool) -> CodebookResult<()> { |
0ca65ffd KS |
168 | if !esc { |
169 | let fill_len = lut_bits - bits; | |
170 | let fill_size = 1 << fill_len; | |
171 | let fill_code = code; | |
172 | let step = lut_bits - fill_len; | |
173 | for j in 0..fill_size { | |
174 | let idx = (fill_code + (j << step)) as usize; | |
d23f3327 | 175 | if table[idx + off] != TABLE_FILL_VALUE { return Err(CodebookError::InvalidCodebook); } |
e243ceb4 | 176 | table[idx + off] = (symidx << 8) | u32::from(bits); |
0ca65ffd KS |
177 | } |
178 | } else { | |
179 | let idx = (code as usize) + off; | |
d23f3327 | 180 | if table[idx] != TABLE_FILL_VALUE { return Err(CodebookError::InvalidCodebook); } |
e243ceb4 | 181 | table[idx] = (symidx << 8) | 0x80 | u32::from(bits); |
0ca65ffd | 182 | } |
d23f3327 | 183 | Ok(()) |
0ca65ffd KS |
184 | } |
185 | ||
186 | fn fill_lut(table: &mut Vec<u32>, mode: CodebookMode, | |
d23f3327 | 187 | off: usize, code: u32, bits: u8, lut_bits: u8, symidx: u32, esc: bool) -> CodebookResult<bool> { |
0ca65ffd | 188 | match mode { |
d23f3327 KS |
189 | CodebookMode::MSB => fill_lut_msb(table, off, code, bits, lut_bits, symidx, esc)?, |
190 | CodebookMode::LSB => fill_lut_lsb(table, off, code, bits, lut_bits, symidx, esc)?, | |
0ca65ffd | 191 | }; |
d23f3327 | 192 | Ok(bits > lut_bits) |
0ca65ffd KS |
193 | } |
194 | ||
195 | fn resize_table(table: &mut Vec<u32>, bits: u8) -> CodebookResult<u32> { | |
196 | let add_size = (1 << bits) as usize; | |
197 | table.reserve(add_size); | |
198 | let cur_off = table.len() as u32; | |
199 | let new_size = table.len() + add_size; | |
200 | if table.capacity() < new_size { return Err(CodebookError::MemoryError); } | |
201 | table.resize(new_size, TABLE_FILL_VALUE); | |
202 | Ok(cur_off) | |
203 | } | |
204 | ||
205 | ||
206 | fn extract_lut_part(code: u32, bits: u8, lut_bits: u8, mode: CodebookMode) -> u32 { | |
207 | match mode { | |
208 | CodebookMode::MSB => code >> (bits - lut_bits), | |
209 | CodebookMode::LSB => code & ((1 << lut_bits) - 1), | |
210 | } | |
211 | } | |
212 | ||
213 | fn extract_esc_part(code: u32, bits: u8, lut_bits: u8, mode: CodebookMode) -> u32 { | |
214 | match mode { | |
215 | CodebookMode::MSB => code & ((1 << (bits - lut_bits)) - 1), | |
216 | CodebookMode::LSB => code >> lut_bits, | |
217 | } | |
218 | } | |
219 | ||
220 | #[derive(Clone,Copy)] | |
221 | struct Code { | |
222 | code: u32, | |
223 | bits: u8, | |
224 | idx: usize, | |
225 | } | |
226 | ||
227 | struct CodeBucket { | |
228 | maxlen: u8, | |
229 | offset: usize, | |
230 | codes: Vec<Code>, | |
231 | } | |
232 | ||
233 | impl CodeBucket { | |
234 | fn new() -> Self { | |
235 | CodeBucket { maxlen: 0, offset: 0, codes: Vec::new() } | |
236 | } | |
237 | fn add_code(&mut self, c: Code) { | |
238 | if c.bits > self.maxlen { self.maxlen = c.bits; } | |
239 | self.codes.push(c); | |
240 | } | |
241 | } | |
242 | ||
243 | type EscapeCodes = HashMap<u32, CodeBucket>; | |
244 | ||
245 | fn add_esc_code(cc: &mut EscapeCodes, key: u32, code: u32, bits: u8, idx: usize) { | |
e243ceb4 | 246 | cc.entry(key).or_insert_with(CodeBucket::new); |
0ca65ffd KS |
247 | let b = cc.get_mut(&key); |
248 | if let Some(bucket) = b { | |
e243ceb4 | 249 | bucket.add_code(Code {code, bits, idx }); |
0ca65ffd KS |
250 | } else { panic!("no bucket when expected!"); } |
251 | } | |
252 | ||
253 | fn build_esc_lut(table: &mut Vec<u32>, | |
254 | mode: CodebookMode, | |
255 | bucket: &CodeBucket) -> CodebookResult<()> { | |
256 | let mut escape_list: EscapeCodes = HashMap::new(); | |
257 | let maxlen = if bucket.maxlen > MAX_LUT_BITS { MAX_LUT_BITS } else { bucket.maxlen }; | |
258 | ||
259 | for code in &bucket.codes { | |
260 | let bits = code.bits; | |
26af5ca8 | 261 | if code.bits <= MAX_LUT_BITS { |
0ca65ffd | 262 | fill_lut(table, mode, bucket.offset, code.code, bits, |
d23f3327 | 263 | maxlen, code.idx as u32, false)?; |
0ca65ffd KS |
264 | } else { |
265 | let ckey = extract_lut_part(code.code, bits, MAX_LUT_BITS, mode); | |
266 | let cval = extract_esc_part(code.code, bits, MAX_LUT_BITS, mode); | |
267 | add_esc_code(&mut escape_list, ckey, cval, bits - MAX_LUT_BITS, code.idx); | |
268 | } | |
269 | } | |
270 | ||
271 | let cur_offset = bucket.offset; | |
272 | for (ckey, sec_bucket) in &mut escape_list { | |
273 | let key = *ckey as u32; | |
274 | let maxlen = min(sec_bucket.maxlen, MAX_LUT_BITS); | |
275 | let new_off = resize_table(table, maxlen)?; | |
276 | fill_lut(table, mode, cur_offset, key, maxlen, | |
d23f3327 | 277 | MAX_LUT_BITS, new_off, true)?; |
0ca65ffd KS |
278 | sec_bucket.offset = new_off as usize; |
279 | } | |
280 | ||
e243ceb4 | 281 | for sec_bucket in escape_list.values() { |
0ca65ffd KS |
282 | build_esc_lut(table, mode, sec_bucket)?; |
283 | } | |
1a151e53 | 284 | |
0ca65ffd KS |
285 | Ok(()) |
286 | } | |
287 | ||
4667915a | 288 | impl<S: Copy> Codebook<S> { |
0ca65ffd | 289 | |
a4bd7707 | 290 | /// Constructs a new `Codebook` instance using provided codebook description and mode. |
0ca65ffd | 291 | pub fn new(cb: &mut CodebookDescReader<S>, mode: CodebookMode) -> CodebookResult<Self> { |
4667915a KS |
292 | let mut maxbits = 0; |
293 | let mut nnz = 0; | |
0ca65ffd KS |
294 | let mut escape_list: EscapeCodes = HashMap::new(); |
295 | ||
296 | let mut symidx: usize = 0; | |
4667915a KS |
297 | for i in 0..cb.len() { |
298 | let bits = cb.bits(i); | |
26488721 | 299 | if bits > 0 { |
e243ceb4 | 300 | nnz += 1; |
26488721 KS |
301 | if cb.code(i) >= (1 << bits) { |
302 | return Err(CodebookError::InvalidCodebook); | |
303 | } | |
304 | } | |
0ca65ffd KS |
305 | maxbits = max(bits, maxbits); |
306 | if bits > MAX_LUT_BITS { | |
307 | let code = cb.code(i); | |
308 | let ckey = extract_lut_part(code, bits, MAX_LUT_BITS, mode); | |
309 | let cval = extract_esc_part(code, bits, MAX_LUT_BITS, mode); | |
310 | add_esc_code(&mut escape_list, ckey, cval, bits - MAX_LUT_BITS, symidx); | |
4667915a | 311 | } |
e243ceb4 | 312 | if bits > 0 { symidx += 1; } |
4667915a KS |
313 | } |
314 | if maxbits == 0 { return Err(CodebookError::InvalidCodebook); } | |
315 | ||
0ca65ffd KS |
316 | if maxbits > MAX_LUT_BITS { maxbits = MAX_LUT_BITS; } |
317 | ||
4667915a | 318 | let tab_len = 1 << maxbits; |
0ca65ffd KS |
319 | let mut table: Vec<u32> = Vec::with_capacity(tab_len); |
320 | let mut syms: Vec<S> = Vec::with_capacity(nnz); | |
4667915a | 321 | if table.capacity() < tab_len { return Err(CodebookError::MemoryError); } |
0ca65ffd KS |
322 | if syms.capacity() < nnz { return Err(CodebookError::MemoryError); } |
323 | table.resize(tab_len, TABLE_FILL_VALUE); | |
4667915a KS |
324 | |
325 | let mut symidx: u32 = 0; | |
326 | for i in 0..cb.len() { | |
327 | let bits = cb.bits(i); | |
0ca65ffd | 328 | let code = cb.code(i); |
4667915a | 329 | if bits == 0 { continue; } |
0ca65ffd | 330 | if bits <= MAX_LUT_BITS { |
d23f3327 | 331 | fill_lut(&mut table, mode, 0, code, bits, maxbits, symidx, false)?; |
0ca65ffd KS |
332 | } else { |
333 | let ckey = extract_lut_part(code, bits, MAX_LUT_BITS, mode) as usize; | |
334 | if table[ckey] == TABLE_FILL_VALUE { | |
335 | let key = ckey as u32; | |
336 | if let Some(bucket) = escape_list.get_mut(&key) { | |
337 | let maxlen = min(bucket.maxlen, MAX_LUT_BITS); | |
338 | let new_off = resize_table(&mut table, maxlen)?; | |
d23f3327 | 339 | fill_lut(&mut table, mode, 0, key, maxlen, MAX_LUT_BITS, new_off, true)?; |
0ca65ffd KS |
340 | bucket.offset = new_off as usize; |
341 | } | |
342 | } | |
4667915a | 343 | } |
e243ceb4 | 344 | symidx += 1; |
4667915a KS |
345 | } |
346 | ||
e243ceb4 | 347 | for bucket in escape_list.values() { |
0ca65ffd KS |
348 | build_esc_lut(&mut table, mode, &bucket)?; |
349 | } | |
350 | ||
4667915a KS |
351 | for i in 0..cb.len() { |
352 | if cb.bits(i) > 0 { | |
353 | syms.push(cb.sym(i)); | |
354 | } | |
355 | } | |
356 | ||
e243ceb4 | 357 | Ok(Codebook { table, syms, lut_bits: maxbits }) |
4667915a KS |
358 | } |
359 | } | |
360 | ||
361 | impl<'a, S: Copy> CodebookReader<S> for BitReader<'a> { | |
362 | #[allow(unused_variables)] | |
363 | fn read_cb(&mut self, cb: &Codebook<S>) -> CodebookResult<S> { | |
0ca65ffd KS |
364 | let mut esc = true; |
365 | let mut idx = 0; | |
366 | let mut lut_bits = cb.lut_bits; | |
367 | while esc { | |
368 | let lut_idx = (self.peek(lut_bits) as usize) + (idx as usize); | |
369 | if cb.table[lut_idx] == TABLE_FILL_VALUE { return Err(CodebookError::InvalidCode); } | |
370 | let bits = cb.table[lut_idx] & 0x7F; | |
371 | esc = (cb.table[lut_idx] & 0x80) != 0; | |
372 | idx = (cb.table[lut_idx] >> 8) as usize; | |
0bbe433e KS |
373 | let skip_bits = if esc { u32::from(lut_bits) } else { bits }; |
374 | if (skip_bits as isize) > self.left() { | |
0ca65ffd KS |
375 | return Err(CodebookError::InvalidCode); |
376 | } | |
e243ceb4 | 377 | self.skip(skip_bits as u32).unwrap(); |
0ca65ffd | 378 | lut_bits = bits as u8; |
4667915a | 379 | } |
0ca65ffd | 380 | Ok(cb.syms[idx]) |
4667915a KS |
381 | } |
382 | } | |
383 | ||
a4bd7707 | 384 | /// Codebook description that stores a list of codewords and their values. |
4667915a KS |
385 | pub struct FullCodebookDescReader<S> { |
386 | data: Vec<FullCodebookDesc<S>>, | |
387 | } | |
388 | ||
389 | impl<S> FullCodebookDescReader<S> { | |
a4bd7707 | 390 | /// Constructs a new `FullCodebookDescReader` instance. |
4667915a | 391 | pub fn new(data: Vec<FullCodebookDesc<S>>) -> Self { |
e243ceb4 | 392 | FullCodebookDescReader { data } |
4667915a KS |
393 | } |
394 | } | |
395 | ||
396 | impl<S: Copy> CodebookDescReader<S> for FullCodebookDescReader<S> { | |
397 | fn bits(&mut self, idx: usize) -> u8 { self.data[idx].bits } | |
398 | fn code(&mut self, idx: usize) -> u32 { self.data[idx].code } | |
399 | fn sym (&mut self, idx: usize) -> S { self.data[idx].sym } | |
400 | fn len(&mut self) -> usize { self.data.len() } | |
401 | } | |
402 | ||
a4bd7707 | 403 | /// Codebook description that stores a list of codewords and their value is equal to the index. |
4667915a KS |
404 | pub struct ShortCodebookDescReader { |
405 | data: Vec<ShortCodebookDesc>, | |
406 | } | |
407 | ||
408 | impl ShortCodebookDescReader { | |
a4bd7707 | 409 | /// Constructs a new `ShortCodebookDescReader` instance. |
4667915a | 410 | pub fn new(data: Vec<ShortCodebookDesc<>>) -> Self { |
e243ceb4 | 411 | ShortCodebookDescReader { data } |
4667915a KS |
412 | } |
413 | } | |
414 | ||
415 | impl CodebookDescReader<u32> for ShortCodebookDescReader { | |
416 | fn bits(&mut self, idx: usize) -> u8 { self.data[idx].bits } | |
417 | fn code(&mut self, idx: usize) -> u32 { self.data[idx].code } | |
418 | fn sym (&mut self, idx: usize) -> u32 { idx as u32 } | |
419 | fn len(&mut self) -> usize { self.data.len() } | |
420 | } | |
421 | ||
a4bd7707 | 422 | /// Flexible codebook description that uses two separate arrays for codeword bits and lengths and a function that maps codeword index into its symbol. |
db63f876 KS |
423 | pub struct TableCodebookDescReader<'a, CodeType:'static, IndexType:'static> { |
424 | bits: &'a [u8], | |
425 | codes: &'a [CodeType], | |
6465a946 KS |
426 | idx_map: fn(usize) -> IndexType, |
427 | } | |
428 | ||
db63f876 | 429 | impl<'a, CodeType, IndexType> TableCodebookDescReader<'a, CodeType, IndexType> { |
a4bd7707 | 430 | /// Constructs a new `TableCodebookDescReader` instance. |
db63f876 | 431 | pub fn new(codes: &'a [CodeType], bits: &'a [u8], idx_map: fn(usize) -> IndexType) -> Self { |
6465a946 KS |
432 | Self { bits, codes, idx_map } |
433 | } | |
434 | } | |
db63f876 | 435 | impl<'a, CodeType: Copy+Into<u32>, IndexType> CodebookDescReader<IndexType> for TableCodebookDescReader<'a, CodeType, IndexType> |
6465a946 KS |
436 | { |
437 | fn bits(&mut self, idx: usize) -> u8 { self.bits[idx] } | |
438 | fn code(&mut self, idx: usize) -> u32 { self.codes[idx].into() } | |
439 | fn sym (&mut self, idx: usize) -> IndexType { (self.idx_map)(idx) } | |
440 | fn len(&mut self) -> usize { self.bits.len() } | |
441 | } | |
442 | ||
4667915a KS |
443 | #[cfg(test)] |
444 | mod test { | |
445 | use super::*; | |
aca89041 | 446 | use crate::io::bitreader::*; |
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447 | |
448 | #[test] | |
449 | fn test_cb() { | |
450 | const BITS: [u8; 2] = [0b01011011, 0b10111100]; | |
451 | let cb_desc: Vec<FullCodebookDesc<i8>> = vec!( | |
452 | FullCodebookDesc { code: 0b0, bits: 1, sym: 16 }, | |
453 | FullCodebookDesc { code: 0b10, bits: 2, sym: -3 }, | |
454 | FullCodebookDesc { code: 0b110, bits: 3, sym: 42 }, | |
455 | FullCodebookDesc { code: 0b1110, bits: 4, sym: -42 } | |
456 | ); | |
457 | let buf = &BITS; | |
fa90ccfb | 458 | let mut br = BitReader::new(buf, BitReaderMode::BE); |
4667915a | 459 | let mut cfr = FullCodebookDescReader::new(cb_desc); |
0ca65ffd | 460 | let cb = Codebook::new(&mut cfr, CodebookMode::MSB).unwrap(); |
4667915a KS |
461 | assert_eq!(br.read_cb(&cb).unwrap(), 16); |
462 | assert_eq!(br.read_cb(&cb).unwrap(), -3); | |
463 | assert_eq!(br.read_cb(&cb).unwrap(), 42); | |
464 | assert_eq!(br.read_cb(&cb).unwrap(), -42); | |
465 | let ret = br.read_cb(&cb); | |
466 | if let Err(e) = ret { | |
467 | assert_eq!(e as i32, CodebookError::InvalidCode as i32); | |
468 | } else { | |
469 | assert_eq!(0, 1); | |
470 | } | |
471 | ||
472 | let scb_desc: Vec<ShortCodebookDesc> = vec!( | |
473 | ShortCodebookDesc { code: 0b0, bits: 1 }, | |
474 | ShortCodebookDesc { code: 0, bits: 0 }, | |
475 | ShortCodebookDesc { code: 0b10, bits: 2 }, | |
476 | ShortCodebookDesc { code: 0, bits: 0 }, | |
477 | ShortCodebookDesc { code: 0, bits: 0 }, | |
478 | ShortCodebookDesc { code: 0b110, bits: 3 }, | |
479 | ShortCodebookDesc { code: 0, bits: 0 }, | |
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480 | ShortCodebookDesc { code: 0b11100, bits: 5 }, |
481 | ShortCodebookDesc { code: 0b11101, bits: 5 }, | |
482 | ShortCodebookDesc { code: 0b1111010, bits: 7 }, | |
483 | ShortCodebookDesc { code: 0b1111011, bits: 7 }, | |
484 | ShortCodebookDesc { code: 0b1111110, bits: 7 }, | |
485 | ShortCodebookDesc { code: 0b11111111, bits: 8 } | |
4667915a | 486 | ); |
fa90ccfb | 487 | let mut br2 = BitReader::new(buf, BitReaderMode::BE); |
4667915a | 488 | let mut cfr = ShortCodebookDescReader::new(scb_desc); |
0ca65ffd | 489 | let cb = Codebook::new(&mut cfr, CodebookMode::MSB).unwrap(); |
4667915a KS |
490 | assert_eq!(br2.read_cb(&cb).unwrap(), 0); |
491 | assert_eq!(br2.read_cb(&cb).unwrap(), 2); | |
492 | assert_eq!(br2.read_cb(&cb).unwrap(), 5); | |
0ca65ffd KS |
493 | assert_eq!(br2.read_cb(&cb).unwrap(), 8); |
494 | ||
06fd8c88 | 495 | assert_eq!(reverse_bits(0b0000_0101_1011_1011_1101_1111_0111_1111, 32), |
0ca65ffd KS |
496 | 0b1111_1110_1111_1011_1101_1101_1010_0000); |
497 | ||
498 | const BITS_LE: [u8; 3] = [0b11101111, 0b01110010, 0b01]; | |
499 | let buf = &BITS_LE; | |
500 | let scble_desc: Vec<ShortCodebookDesc> = vec!( | |
501 | ShortCodebookDesc { code: 0b00, bits: 2 }, | |
502 | ShortCodebookDesc { code: 0, bits: 0 }, | |
503 | ShortCodebookDesc { code: 0b01, bits: 2 }, | |
504 | ShortCodebookDesc { code: 0, bits: 0 }, | |
505 | ShortCodebookDesc { code: 0, bits: 0 }, | |
506 | ShortCodebookDesc { code: 0b011, bits: 3 }, | |
507 | ShortCodebookDesc { code: 0, bits: 0 }, | |
508 | ShortCodebookDesc { code: 0b10111, bits: 5 }, | |
509 | ShortCodebookDesc { code: 0b00111, bits: 5 }, | |
510 | ShortCodebookDesc { code: 0b0101111, bits: 7 }, | |
511 | ShortCodebookDesc { code: 0b0111111, bits: 7 }, | |
512 | ShortCodebookDesc { code: 0b1011101111, bits: 10 } | |
513 | ); | |
fa90ccfb | 514 | let mut brl = BitReader::new(buf, BitReaderMode::LE); |
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515 | let mut cfr = ShortCodebookDescReader::new(scble_desc); |
516 | let cb = Codebook::new(&mut cfr, CodebookMode::LSB).unwrap(); | |
517 | assert_eq!(brl.read_cb(&cb).unwrap(), 11); | |
518 | assert_eq!(brl.read_cb(&cb).unwrap(), 0); | |
519 | assert_eq!(brl.read_cb(&cb).unwrap(), 7); | |
520 | assert_eq!(brl.read_cb(&cb).unwrap(), 0); | |
4667915a KS |
521 | } |
522 | } |