mirror of
https://github.com/qgis/QGIS.git
synced 2025-02-23 00:02:38 -05:00
287 lines
11 KiB
C++
287 lines
11 KiB
C++
|
/*
|
||
|
|
===============================================================================
|
||
|
|
|
||
|
|
FILE: decoder.hpp
|
||
|
|
|
||
|
|
CONTENTS:
|
||
|
|
Decoder stuff
|
||
|
|
|
||
|
|
PROGRAMMERS:
|
||
|
|
|
||
|
|
martin.isenburg@rapidlasso.com - http://rapidlasso.com
|
||
|
|
uday.karan@gmail.com - Hobu, Inc.
|
||
|
|
|
||
|
|
COPYRIGHT:
|
||
|
|
|
||
|
|
(c) 2007-2014, martin isenburg, rapidlasso - tools to catch reality
|
||
|
|
(c) 2014, Uday Verma, Hobu, Inc.
|
||
|
|
|
||
|
|
This is free software; you can redistribute and/or modify it under the
|
||
|
|
terms of the GNU Lesser General Licence as published by the Free Software
|
||
|
|
Foundation. See the COPYING file for more information.
|
||
|
|
|
||
|
|
This software is distributed WITHOUT ANY WARRANTY and without even the
|
||
|
|
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
||
|
|
|
||
|
|
CHANGE HISTORY:
|
||
|
|
|
||
|
|
===============================================================================
|
||
|
|
*/
|
||
|
|
|
||
|
|
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
||
|
|
// -
|
||
|
|
// **************************** -
|
||
|
|
// ARITHMETIC CODING EXAMPLES -
|
||
|
|
// **************************** -
|
||
|
|
// -
|
||
|
|
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
||
|
|
// -
|
||
|
|
// Fast arithmetic coding implementation -
|
||
|
|
// -> 32-bit variables, 32-bit product, periodic updates, table decoding -
|
||
|
|
// -
|
||
|
|
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
||
|
|
// -
|
||
|
|
// Version 1.00 - April 25, 2004 -
|
||
|
|
// -
|
||
|
|
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
||
|
|
// -
|
||
|
|
// WARNING -
|
||
|
|
// ========= -
|
||
|
|
// -
|
||
|
|
// The only purpose of this program is to demonstrate the basic principles -
|
||
|
|
// of arithmetic coding. The original version of this code can be found in -
|
||
|
|
// Digital Signal Compression: Principles and Practice -
|
||
|
|
// (Cambridge University Press, 2011, ISBN: 9780511984655) -
|
||
|
|
// -
|
||
|
|
// Copyright (c) 2019 by Amir Said (said@ieee.org) & -
|
||
|
|
// William A. Pearlman (pearlw@ecse.rpi.edu) -
|
||
|
|
// -
|
||
|
|
// Redistribution and use in source and binary forms, with or without -
|
||
|
|
// modification, are permitted provided that the following conditions are -
|
||
|
|
// met: -
|
||
|
|
// -
|
||
|
|
// 1. Redistributions of source code must retain the above copyright notice, -
|
||
|
|
// this list of conditions and the following disclaimer. -
|
||
|
|
// -
|
||
|
|
// 2. Redistributions in binary form must reproduce the above copyright -
|
||
|
|
// notice, this list of conditions and the following disclaimer in the -
|
||
|
|
// documentation and/or other materials provided with the distribution. -
|
||
|
|
// -
|
||
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -
|
||
|
|
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED -
|
||
|
|
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A -
|
||
|
|
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER -
|
||
|
|
// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, -
|
||
|
|
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, -
|
||
|
|
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR -
|
||
|
|
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF -
|
||
|
|
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING -
|
||
|
|
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS -
|
||
|
|
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -
|
||
|
|
// -
|
||
|
|
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
||
|
|
// -
|
||
|
|
// A description of the arithmetic coding method used here is available in -
|
||
|
|
// -
|
||
|
|
// Lossless Compression Handbook, ed. K. Sayood -
|
||
|
|
// Chapter 5: Arithmetic Coding (A. Said), pp. 101-152, Academic Press, 2003 -
|
||
|
|
// -
|
||
|
|
// A. Said, Introduction to Arithetic Coding Theory and Practice -
|
||
|
|
// HP Labs report HPL-2004-76 - http://www.hpl.hp.com/techreports/ -
|
||
|
|
// -
|
||
|
|
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
|
||
|
|
|
||
|
|
|
||
|
|
#ifndef __decoder_hpp__
|
||
|
|
#define __decoder_hpp__
|
||
|
|
|
||
|
|
#include <cassert>
|
||
|
|
|
||
|
|
#include "common/types.hpp"
|
||
|
|
|
||
|
|
namespace laszip {
|
||
|
|
namespace decoders {
|
||
|
|
template<
|
||
|
|
typename TInputStream
|
||
|
|
>
|
||
|
|
struct arithmetic {
|
||
|
|
arithmetic(TInputStream& in) :
|
||
|
|
instream(in), value(0) {
|
||
|
|
length = AC__MaxLength;
|
||
|
|
}
|
||
|
|
|
||
|
|
~arithmetic() {
|
||
|
|
}
|
||
|
|
|
||
|
|
void readInitBytes() {
|
||
|
|
value =
|
||
|
|
(instream.getByte() << 24) |
|
||
|
|
(instream.getByte() << 16) |
|
||
|
|
(instream.getByte() << 8) |
|
||
|
|
instream.getByte();
|
||
|
|
}
|
||
|
|
|
||
|
|
template<typename TEntropyModel>
|
||
|
|
U32 decodeBit(TEntropyModel& m) {
|
||
|
|
U32 x = m.bit_0_prob * (length >> BM__LengthShift); // product l x p0
|
||
|
|
U32 sym = (value >= x); // decision
|
||
|
|
// update & shift interval
|
||
|
|
if (sym == 0) {
|
||
|
|
length = x;
|
||
|
|
++m.bit_0_count;
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
value -= x; // shifted interval base = 0
|
||
|
|
length -= x;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (length < AC__MinLength) renorm_dec_interval(); // renormalization
|
||
|
|
if (--m.bits_until_update == 0) m.update(); // periodic model update
|
||
|
|
|
||
|
|
return sym; // return data bit value
|
||
|
|
}
|
||
|
|
|
||
|
|
template<typename TEntropyModel>
|
||
|
|
U32 decodeSymbol(TEntropyModel& m) {
|
||
|
|
U32 n, sym, x, y = length;
|
||
|
|
|
||
|
|
if (m.decoder_table) { // use table look-up for faster decoding
|
||
|
|
unsigned dv = value / (length >>= DM__LengthShift);
|
||
|
|
unsigned t = dv >> m.table_shift;
|
||
|
|
|
||
|
|
sym = m.decoder_table[t]; // initial decision based on table look-up
|
||
|
|
n = m.decoder_table[t+1] + 1;
|
||
|
|
|
||
|
|
while (n > sym + 1) { // finish with bisection search
|
||
|
|
U32 k = (sym + n) >> 1;
|
||
|
|
if (m.distribution[k] > dv) n = k; else sym = k;
|
||
|
|
}
|
||
|
|
|
||
|
|
// compute products
|
||
|
|
x = m.distribution[sym] * length;
|
||
|
|
if (sym != m.last_symbol) y = m.distribution[sym+1] * length;
|
||
|
|
}
|
||
|
|
else { // decode using only multiplications
|
||
|
|
x = sym = 0;
|
||
|
|
length >>= DM__LengthShift;
|
||
|
|
U32 k = (n = m.symbols) >> 1;
|
||
|
|
// decode via bisection search
|
||
|
|
do {
|
||
|
|
U32 z = length * m.distribution[k];
|
||
|
|
if (z > value) {
|
||
|
|
n = k;
|
||
|
|
y = z; // value is smaller
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
sym = k;
|
||
|
|
x = z; // value is larger or equal
|
||
|
|
}
|
||
|
|
} while ((k = (sym + n) >> 1) != sym);
|
||
|
|
}
|
||
|
|
|
||
|
|
value -= x; // update interval
|
||
|
|
length = y - x;
|
||
|
|
|
||
|
|
if (length < AC__MinLength) renorm_dec_interval(); // renormalization
|
||
|
|
|
||
|
|
++m.symbol_count[sym];
|
||
|
|
if (--m.symbols_until_update == 0) m.update(); // periodic model update
|
||
|
|
|
||
|
|
return sym;
|
||
|
|
}
|
||
|
|
|
||
|
|
U32 readBit() {
|
||
|
|
U32 sym = value / (length >>= 1); // decode symbol, change length
|
||
|
|
value -= length * sym; // update interval
|
||
|
|
|
||
|
|
if (length < AC__MinLength) renorm_dec_interval(); // renormalization
|
||
|
|
|
||
|
|
return sym;
|
||
|
|
}
|
||
|
|
|
||
|
|
U32 readBits(U32 bits) {
|
||
|
|
assert(bits && (bits <= 32));
|
||
|
|
|
||
|
|
if (bits > 19) {
|
||
|
|
U32 tmp = readShort();
|
||
|
|
bits = bits - 16;
|
||
|
|
U32 tmp1 = readBits(bits) << 16;
|
||
|
|
return (tmp1|tmp);
|
||
|
|
}
|
||
|
|
|
||
|
|
U32 sym = value / (length >>= bits);// decode symbol, change length
|
||
|
|
value -= length * sym; // update interval
|
||
|
|
|
||
|
|
if (length < AC__MinLength) renorm_dec_interval(); // renormalization
|
||
|
|
return sym;
|
||
|
|
}
|
||
|
|
|
||
|
|
U8 readByte() {
|
||
|
|
U32 sym = value / (length >>= 8); // decode symbol, change length
|
||
|
|
value -= length * sym; // update interval
|
||
|
|
|
||
|
|
if (length < AC__MinLength) renorm_dec_interval(); // renormalization
|
||
|
|
|
||
|
|
assert(sym < (1<<8));
|
||
|
|
|
||
|
|
return (U8)sym;
|
||
|
|
}
|
||
|
|
|
||
|
|
U16 readShort() {
|
||
|
|
U32 sym = value / (length >>= 16); // decode symbol, change length
|
||
|
|
value -= length * sym; // update interval
|
||
|
|
|
||
|
|
if (length < AC__MinLength) renorm_dec_interval(); // renormalization
|
||
|
|
|
||
|
|
assert(sym < (1<<16));
|
||
|
|
|
||
|
|
return (U16)sym;
|
||
|
|
}
|
||
|
|
|
||
|
|
U32 readInt() {
|
||
|
|
U32 lowerInt = readShort();
|
||
|
|
U32 upperInt = readShort();
|
||
|
|
return (upperInt<<16)|lowerInt;
|
||
|
|
}
|
||
|
|
|
||
|
|
F32 readFloat() { /* danger in float reinterpretation */
|
||
|
|
U32I32F32 u32i32f32;
|
||
|
|
u32i32f32.u32 = readInt();
|
||
|
|
return u32i32f32.f32;
|
||
|
|
}
|
||
|
|
|
||
|
|
U64 readInt64() {
|
||
|
|
U64 lowerInt = readInt();
|
||
|
|
U64 upperInt = readInt();
|
||
|
|
return (upperInt<<32)|lowerInt;
|
||
|
|
}
|
||
|
|
|
||
|
|
F64 readDouble() { /* danger in float reinterpretation */
|
||
|
|
U64I64F64 u64i64f64;
|
||
|
|
u64i64f64.u64 = readInt64();
|
||
|
|
return u64i64f64.f64;
|
||
|
|
}
|
||
|
|
|
||
|
|
TInputStream& getInStream() {
|
||
|
|
return instream;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
arithmetic<TInputStream>(const arithmetic<TInputStream>&) = delete;
|
||
|
|
arithmetic<TInputStream>& operator = (const arithmetic<TInputStream>&) = delete;
|
||
|
|
|
||
|
|
private:
|
||
|
|
void renorm_dec_interval() {
|
||
|
|
do { // read least-significant byte
|
||
|
|
value = (value << 8) | instream.getByte();
|
||
|
|
} while ((length <<= 8) < AC__MinLength); // length multiplied by 256
|
||
|
|
}
|
||
|
|
|
||
|
|
TInputStream& instream;
|
||
|
|
U32 value, length;
|
||
|
|
};
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif // __decoder_hpp__
|