dlib C++ Library - entropy_encoder_model_kernel_1.h

// Copyright (C) 2004 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_ENTROPY_ENCODER_MODEL_KERNEl_1_
#define DLIB_ENTROPY_ENCODER_MODEL_KERNEl_1_
#include "../algs.h"
#include "entropy_encoder_model_kernel_abstract.h"
#include "../assert.h"
namespace dlib
{
 template <
 unsigned long alphabet_size,
 typename entropy_encoder,
 typename cc
 >
 class entropy_encoder_model_kernel_1 
 {
 /*!
 REQUIREMENTS ON cc
 cc is an implementation of conditioning_class/conditioning_class_kernel_abstract.h
 cc::get_alphabet_size() == alphabet_size+1
 INITIAL VALUE
 Initially this object's finite context model is empty
 CONVENTION
 &get_entropy_encoder() == coder
 &order_0.get_global_state() == &gs
 This is an order-0 model. The last symbol in the order-0 context is 
 an escape into the order minus 1 context.
 !*/
 public:
 typedef entropy_encoder entropy_encoder_type;
 entropy_encoder_model_kernel_1 (
 entropy_encoder& coder
 );
 virtual ~entropy_encoder_model_kernel_1 (
 );
 
 inline void clear(
 );
 inline void encode (
 unsigned long symbol
 );
 entropy_encoder& get_entropy_encoder (
 ) { return coder; }
 static unsigned long get_alphabet_size (
 ) { return alphabet_size; }
 private:
 entropy_encoder& coder;
 typename cc::global_state_type gs;
 cc order_0;
 // restricted functions
 entropy_encoder_model_kernel_1(entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>&); // copy constructor
 entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>& operator=(entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>&); // assignment operator
 }; 
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
 // member function definitions
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
 template <
 unsigned long alphabet_size,
 typename entropy_encoder,
 typename cc
 >
 entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>::
 entropy_encoder_model_kernel_1 (
 entropy_encoder& coder_
 ) : 
 coder(coder_),
 order_0(gs)
 {
 COMPILE_TIME_ASSERT( 1 < alphabet_size && alphabet_size < 65535 );
 }
// ----------------------------------------------------------------------------------------
 template <
 unsigned long alphabet_size,
 typename entropy_encoder,
 typename cc
 >
 entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>::
 ~entropy_encoder_model_kernel_1 (
 )
 {
 }
 
// ----------------------------------------------------------------------------------------
 template <
 unsigned long alphabet_size,
 typename entropy_encoder,
 typename cc
 >
 void entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>::
 clear(
 )
 {
 order_0.clear();
 }
// ----------------------------------------------------------------------------------------
 template <
 unsigned long alphabet_size,
 typename entropy_encoder,
 typename cc
 >
 void entropy_encoder_model_kernel_1<alphabet_size,entropy_encoder,cc>::
 encode (
 unsigned long symbol
 )
 {
 unsigned long low_count = 0, high_count = 0, total_count = 0;
 // if we have seen this symbol in the order-0 context
 if (order_0.get_range(symbol,low_count,high_count,total_count))
 {
 // update the count for this symbol
 order_0.increment_count(symbol,2);
 // encode this symbol
 coder.encode(low_count,high_count,total_count); 
 return;
 }
 
 // if we are here then the symbol does not appear in the order-0 context
 
 // since we have never seen the current symbol in this context
 // escape from order-0 context
 order_0.get_range(alphabet_size,low_count,high_count,total_count);
 coder.encode(low_count,high_count,total_count);
 // increment the count for the escape symbol
 order_0.increment_count(alphabet_size); 
 // update the count for this symbol
 order_0.increment_count(symbol,2);
 // use order minus one context
 coder.encode(symbol,symbol+1,alphabet_size);
 
 }
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_ENTROPY_ENCODER_MODEL_KERNEl_1_