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// 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_
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