/* =============================================================================== FILE: encoder.hpp CONTENTS: Encoder 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 __encoder_hpp__ #define __encoder_hpp__ #include "common/types.hpp" namespace laszip { namespace encoders { template< typename TOutStream > struct arithmetic { arithmetic(TOutStream& out) : outstream(out) { outbuffer = new U8[2*AC_BUFFER_SIZE]; endbuffer = outbuffer + 2 * AC_BUFFER_SIZE; base = 0; length = AC__MaxLength; outbyte = outbuffer; endbyte = endbuffer; } ~arithmetic() { delete [] outbuffer; } void done() { U32 init_base = base; // done encoding: set final data bytes BOOL another_byte = TRUE; if (length > 2 * AC__MinLength) { base += AC__MinLength; // base offset length = AC__MinLength >> 1; // set new length for 1 more byte } else { base += AC__MinLength >> 1; // base offset length = AC__MinLength >> 9; // set new length for 2 more bytes another_byte = FALSE; } if (init_base > base) propagate_carry(); // overflow = carry renorm_enc_interval(); // renormalization = output last bytes if (endbyte != endbuffer) { assert(outbyte < outbuffer + AC_BUFFER_SIZE); outstream.putBytes(outbuffer + AC_BUFFER_SIZE, AC_BUFFER_SIZE); } I64 buffer_size = outbyte - outbuffer; if (buffer_size) outstream.putBytes(outbuffer, (U32)buffer_size); // write two or three zero bytes to be in sync with the decoder's byte reads outstream.putByte(0); outstream.putByte(0); if (another_byte) outstream.putByte(0); } /* Encode a bit with modelling */ template void encodeBit(EntropyModel& m, U32 sym) { assert(sym <= 1); U32 x = m.bit_0_prob * (length >> BM__LengthShift); // product l x p0 // update interval if (sym == 0) { length = x; ++m.bit_0_count; } else { U32 init_base = base; base += x; length -= x; if (init_base > base) propagate_carry(); // overflow = carry } if (length < AC__MinLength) renorm_enc_interval(); // renormalization if (--m.bits_until_update == 0) m.update(); // periodic model update } /* Encode a symbol with modelling */ template void encodeSymbol(EntropyModel& m, U32 sym) { assert(sym <= m.last_symbol); U32 x, init_base = base; // compute products if (sym == m.last_symbol) { x = m.distribution[sym] * (length >> DM__LengthShift); base += x; // update interval length -= x; // no product needed } else { x = m.distribution[sym] * (length >>= DM__LengthShift); base += x; // update interval length = m.distribution[sym+1] * length - x; } if (init_base > base) propagate_carry(); // overflow = carry if (length < AC__MinLength) renorm_enc_interval(); // renormalization ++m.symbol_count[sym]; if (--m.symbols_until_update == 0) m.update(); // periodic model update } /* Encode a bit without modelling */ void writeBit(U32 sym) { assert(sym < 2); U32 init_base = base; base += sym * (length >>= 1); // new interval base and length if (init_base > base) propagate_carry(); // overflow = carry if (length < AC__MinLength) renorm_enc_interval(); // renormalization } void writeBits(U32 bits, U32 sym) { assert(bits && (bits <= 32) && (sym < (1u< 19) { writeShort(sym&U16_MAX); sym = sym >> 16; bits = bits - 16; } U32 init_base = base; base += sym * (length >>= bits); // new interval base and length if (init_base > base) propagate_carry(); // overflow = carry if (length < AC__MinLength) renorm_enc_interval(); // renormalization } void writeByte(U8 sym) { U32 init_base = base; base += (U32)(sym) * (length >>= 8); // new interval base and length if (init_base > base) propagate_carry(); // overflow = carry if (length < AC__MinLength) renorm_enc_interval(); // renormalization } void writeShort(U16 sym) { U32 init_base = base; base += (U32)(sym) * (length >>= 16); // new interval base and length if (init_base > base) propagate_carry(); // overflow = carry if (length < AC__MinLength) renorm_enc_interval(); // renormalization } void writeInt(U32 sym) { writeShort((U16)(sym & 0xFFFF)); // lower 16 bits writeShort((U16)(sym >> 16)); // UPPER 16 bits } void writeFloat(F32 sym) /* danger in float reinterpretation */ { U32I32F32 u32i32f32; u32i32f32.f32 = sym; writeInt(u32i32f32.u32); } void writeInt64(U64 sym) { writeInt((U32)(sym & 0xFFFFFFFF)); // lower 32 bits writeInt((U32)(sym >> 32)); // UPPER 32 bits } void writeDouble(F64 sym) /* danger in float reinterpretation */ { U64I64F64 u64i64f64; u64i64f64.f64 = sym; writeInt64(u64i64f64.u64); } TOutStream& getOutStream() { return outstream; } private: void propagate_carry() { U8 * b; if (outbyte == outbuffer) b = endbuffer - 1; else b = outbyte - 1; while (*b== 0xFFU) { *b = 0; if (b == outbuffer) b= endbuffer - 1; else b--; assert(outbuffer <= b); assert(b < endbuffer); assert(outbyte < endbuffer); } ++*b; } void renorm_enc_interval() { do { // output and discard top byte assert(outbuffer <= outbyte); assert(outbyte < endbuffer); assert(outbyte < endbyte); *outbyte++ = (U8)(base >> 24); if (outbyte == endbyte) manage_outbuffer(); base <<= 8; } while ((length <<= 8) < AC__MinLength); // length multiplied by 256 } void manage_outbuffer() { if (outbyte == endbuffer) outbyte = outbuffer; outstream.putBytes(outbyte, AC_BUFFER_SIZE); endbyte = outbyte + AC_BUFFER_SIZE; assert(endbyte > outbyte); assert(outbyte < endbuffer); } arithmetic(const arithmetic&) = delete; arithmetic& operator = (const arithmetic&) = delete; private: U8* outbuffer; U8* endbuffer; U8* outbyte; U8* endbyte; U32 base, value, length; TOutStream& outstream; }; } } #endif // __encoder_hpp__