// Encode a symbol with modelling
public void encodeSymbol(ArithmeticModel m, uint sym)
{
Debug.Assert(m != null);
Debug.Assert(sym <= m.last_symbol);
uint x, init_interval_base = interval_base;
// compute products
if (sym == m.last_symbol)
{
x = m.distribution[sym] * (length >> DM.LengthShift);
interval_base += x; // update interval
length -= x; // no product needed
}
else
{
x = m.distribution[sym] * (length >>= DM.LengthShift);
interval_base += x; // update interval
length = m.distribution[sym + 1] * length - x;
}
if (init_interval_base > interval_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
}
}
public LASwriteItemCompressed_BYTE_v2(ArithmeticEncoder enc, uint number)
{
// set encoder
Debug.Assert(enc!=null);
this.enc=enc;
Debug.Assert(number>0);
this.number=number;
// create models and integer compressors
m_byte=new ArithmeticModel[number];
for(uint i=0; i<number; i++)
{
m_byte[i]=enc.createSymbolModel(256);
}
// create last item
last_item=new byte[number];
}
public LASwriteItemCompressed_BYTE_v2(ArithmeticEncoder enc, uint number)
{
// set encoder
Debug.Assert(enc != null);
this.enc = enc;
Debug.Assert(number > 0);
this.number = number;
// create models and integer compressors
m_byte = new ArithmeticModel[number];
for (uint i = 0; i < number; i++)
{
m_byte[i] = enc.createSymbolModel(256);
}
// create last item
last_item = new byte[number];
}
public LASreadItemCompressed_BYTE_v2(ArithmeticDecoder dec, uint number)
{
// set decoder
Debug.Assert(dec!=null);
this.dec=dec;
Debug.Assert(number>0);
this.number=number;
// create models and integer compressors
m_byte=new ArithmeticModel[number];
for(uint i=0; i<number; i++)
{
m_byte[i]=dec.createSymbolModel(256);
}
// create last item
last_item=new byte[number];
}
public LASreadItemCompressed_BYTE_v2(ArithmeticDecoder dec, uint number)
{
// set decoder
Debug.Assert(dec != null);
this.dec = dec;
Debug.Assert(number > 0);
this.number = number;
// create models and integer compressors
m_byte = new ArithmeticModel[number];
for (uint i = 0; i < number; i++)
{
m_byte[i] = dec.createSymbolModel(256);
}
// create last item
last_item = new byte[number];
}
// Manage Decompressor
public void initDecompressor()
{
Debug.Assert(dec != null);
// maybe create the models
if (mBits == null)
{
mBits = new ArithmeticModel[contexts];
for (uint i = 0; i < contexts; i++)
{
mBits[i] = dec.createSymbolModel(corr_bits + 1);
}
#if !COMPRESS_ONLY_K
mCorrector = new ArithmeticModel[corr_bits + 1];
mCorrectorBit = dec.createBitModel();
for (uint i = 1; i <= corr_bits; i++)
{
if (i <= bits_high)
{
mCorrector[i] = dec.createSymbolModel(1u << (int)i);
}
else
{
mCorrector[i] = dec.createSymbolModel(1u << (int)bits_high);
}
}
#endif
}
// certainly init the models
for (uint i = 0; i < contexts; i++)
{
dec.initSymbolModel(mBits[i]);
}
#if !COMPRESS_ONLY_K
dec.initBitModel(mCorrectorBit);
for (uint i = 1; i <= corr_bits; i++)
{
dec.initSymbolModel(mCorrector[i]);
}
#endif
}
int readCorrector(ArithmeticModel model)
{
int c;
// decode within which interval the corrector is falling
k=dec.decodeSymbol(model);
// decode the exact location of the corrector within the interval
#if COMPRESS_ONLY_K
if(k!=0) // then c is either smaller than 0 or bigger than 1
{
if(k<32)
{
c=(int)dec.readBits(k);
if(c>=(1<<((int)k-1))) // if c is in the interval [ 2^(k-1) ... + 2^k - 1 ]
{
// so we translate c back into the interval [ 2^(k-1) + 1 ... 2^k ] by adding 1
c+=1;
}
else // otherwise c is in the interval [ 0 ... + 2^(k-1) - 1 ]
{
// so we translate c back into the interval [ - (2^k - 1) ... - (2^(k-1)) ] by subtracting (2^k - 1)
c-=((1<<(int)k)-1);
}
}
else
{
c=corr_min;
}
}
else // then c is either 0 or 1
{
c=(int)dec.readBit();
}
#else // COMPRESS_ONLY_K
if(k!=0) // then c is either smaller than 0 or bigger than 1
{
if(k<32)
{
if(k<=bits_high) // for small k we can do this in one step
{
// decompress c with the range coder
c=(int)dec.decodeSymbol(mCorrector[k]);
}
else
{
// for larger k we need to do this in two steps
uint k1=k-bits_high;
// decompress higher bits with table
c=(int)dec.decodeSymbol(mCorrector[k]);
// read lower bits raw
int c1=(int)dec.readBits(k1);
// put the corrector back together
c=(c<<(int)k1)|c1;
}
// translate c back into its correct interval
if(c>=(1<<((int)k-1))) // if c is in the interval [ 2^(k-1) ... + 2^k - 1 ]
{
// so we translate c back into the interval [ 2^(k-1) + 1 ... 2^k ] by adding 1
c+=1;
}
else // otherwise c is in the interval [ 0 ... + 2^(k-1) - 1 ]
{
// so we translate c back into the interval [ - (2^k - 1) ... - (2^(k-1)) ] by subtracting (2^k - 1)
c-=((1<<(int)k)-1);
}
}
else
{
c=corr_min;
}
}
else // then c is either 0 or 1
{
c=(int)dec.decodeBit(mCorrectorBit);
}
#endif // COMPRESS_ONLY_K
return c;
}
void writeCorrector(int c, ArithmeticModel model)
{
// find the tighest interval [ - (2^k - 1) ... + (2^k) ] that contains c
k=0;
// do this by checking the absolute value of c (adjusted for the case that c is 2^k)
uint c1=(uint)(c<=0?-c:c-1);
// this loop could be replaced with more efficient code
while(c1!=0)
{
c1=c1>>1;
k=k+1;
}
// the number k is between 0 and corr_bits and describes the interval the corrector falls into
// we can compress the exact location of c within this interval using k bits
enc.encodeSymbol(model, k);
#if COMPRESS_ONLY_K
if(k!=0) // then c is either smaller than 0 or bigger than 1
{
Debug.Assert((c!=0)&&(c!=1));
if(k<32)
{
// translate the corrector c into the k-bit interval [ 0 ... 2^k - 1 ]
if(c<0) // then c is in the interval [ - (2^k - 1) ... - (2^(k-1)) ]
{
// so we translate c into the interval [ 0 ... + 2^(k-1) - 1 ] by adding (2^k - 1)
enc.writeBits((int)k, (uint)(c+((1<<(int)k)-1)));
}
else // then c is in the interval [ 2^(k-1) + 1 ... 2^k ]
{
// so we translate c into the interval [ 2^(k-1) ... + 2^k - 1 ] by subtracting 1
enc.writeBits((int)k, (uint)(c-1));
}
}
}
else // then c is 0 or 1
{
Debug.Assert((c==0)||(c==1));
enc.writeBit((uint)c);
}
#else // COMPRESS_ONLY_K
if(k!=0) // then c is either smaller than 0 or bigger than 1
{
Debug.Assert((c!=0)&&(c!=1));
if(k<32)
{
// translate the corrector c into the k-bit interval [ 0 ... 2^k - 1 ]
if(c<0) // then c is in the interval [ - (2^k - 1) ... - (2^(k-1)) ]
{
// so we translate c into the interval [ 0 ... + 2^(k-1) - 1 ] by adding (2^k - 1)
c+=((1<<(int)k)-1);
}
else // then c is in the interval [ 2^(k-1) + 1 ... 2^k ]
{
// so we translate c into the interval [ 2^(k-1) ... + 2^k - 1 ] by subtracting 1
c-=1;
}
if(k<=bits_high) // for small k we code the interval in one step
{
// compress c with the range coder
enc.encodeSymbol(mCorrector[k], (uint)c);
}
else // for larger k we need to code the interval in two steps
{
// figure out how many lower bits there are
int k1=(int)k-(int)bits_high;
// c1 represents the lowest k-bits_high+1 bits
c1=(uint)(c&((1<<k1)-1));
// c represents the highest bits_high bits
c=c>>k1;
// compress the higher bits using a context table
enc.encodeSymbol(mCorrector[k], (uint)c);
// store the lower k1 bits raw
enc.writeBits(k1, c1);
}
}
}
else // then c is 0 or 1
{
Debug.Assert((c==0)||(c==1));
enc.encodeBit(mCorrectorBit, (uint)c);
}
#endif // COMPRESS_ONLY_K
}
// Manage Decompressor
public void initDecompressor()
{
Debug.Assert(dec!=null);
// maybe create the models
if(mBits==null)
{
mBits=new ArithmeticModel[contexts];
for(uint i=0; i<contexts; i++)
{
mBits[i]=dec.createSymbolModel(corr_bits+1);
}
#if !COMPRESS_ONLY_K
mCorrector=new ArithmeticModel[corr_bits+1];
mCorrectorBit=dec.createBitModel();
for(uint i=1; i<=corr_bits; i++)
{
if(i<=bits_high)
{
mCorrector[i]=dec.createSymbolModel(1u<<(int)i);
}
else
{
mCorrector[i]=dec.createSymbolModel(1u<<(int)bits_high);
}
}
#endif
}
// certainly init the models
for(uint i=0; i<contexts; i++)
{
dec.initSymbolModel(mBits[i]);
}
#if !COMPRESS_ONLY_K
dec.initBitModel(mCorrectorBit);
for(uint i=1; i<=corr_bits; i++)
{
dec.initSymbolModel(mCorrector[i]);
}
#endif
}
int readCorrector(ArithmeticModel model)
{
int c;
// decode within which interval the corrector is falling
k = dec.decodeSymbol(model);
// decode the exact location of the corrector within the interval
#if COMPRESS_ONLY_K
if (k != 0) // then c is either smaller than 0 or bigger than 1
{
if (k < 32)
{
c = (int)dec.readBits(k);
if (c >= (1 << ((int)k - 1))) // if c is in the interval [ 2^(k-1) ... + 2^k - 1 ]
{
// so we translate c back into the interval [ 2^(k-1) + 1 ... 2^k ] by adding 1
c += 1;
}
else // otherwise c is in the interval [ 0 ... + 2^(k-1) - 1 ]
{
// so we translate c back into the interval [ - (2^k - 1) ... - (2^(k-1)) ] by subtracting (2^k - 1)
c -= ((1 << (int)k) - 1);
}
}
else
{
c = corr_min;
}
}
else // then c is either 0 or 1
{
c = (int)dec.readBit();
}
#else // COMPRESS_ONLY_K
if (k != 0) // then c is either smaller than 0 or bigger than 1
{
if (k < 32)
{
if (k <= bits_high) // for small k we can do this in one step
{
// decompress c with the range coder
c = (int)dec.decodeSymbol(mCorrector[k]);
}
else
{
// for larger k we need to do this in two steps
uint k1 = k - bits_high;
// decompress higher bits with table
c = (int)dec.decodeSymbol(mCorrector[k]);
// read lower bits raw
int c1 = (int)dec.readBits(k1);
// put the corrector back together
c = (c << (int)k1) | c1;
}
// translate c back into its correct interval
if (c >= (1 << ((int)k - 1))) // if c is in the interval [ 2^(k-1) ... + 2^k - 1 ]
{
// so we translate c back into the interval [ 2^(k-1) + 1 ... 2^k ] by adding 1
c += 1;
}
else // otherwise c is in the interval [ 0 ... + 2^(k-1) - 1 ]
{
// so we translate c back into the interval [ - (2^k - 1) ... - (2^(k-1)) ] by subtracting (2^k - 1)
c -= ((1 << (int)k) - 1);
}
}
else
{
c = corr_min;
}
}
else // then c is either 0 or 1
{
c = (int)dec.decodeBit(mCorrectorBit);
}
#endif // COMPRESS_ONLY_K
return(c);
}
void writeCorrector(int c, ArithmeticModel model)
{
// find the tighest interval [ - (2^k - 1) ... + (2^k) ] that contains c
k = 0;
// do this by checking the absolute value of c (adjusted for the case that c is 2^k)
uint c1 = (uint)(c <= 0?-c:c - 1);
// this loop could be replaced with more efficient code
while (c1 != 0)
{
c1 = c1 >> 1;
k = k + 1;
}
// the number k is between 0 and corr_bits and describes the interval the corrector falls into
// we can compress the exact location of c within this interval using k bits
enc.encodeSymbol(model, k);
#if COMPRESS_ONLY_K
if (k != 0) // then c is either smaller than 0 or bigger than 1
{
Debug.Assert((c != 0) && (c != 1));
if (k < 32)
{
// translate the corrector c into the k-bit interval [ 0 ... 2^k - 1 ]
if (c < 0) // then c is in the interval [ - (2^k - 1) ... - (2^(k-1)) ]
{
// so we translate c into the interval [ 0 ... + 2^(k-1) - 1 ] by adding (2^k - 1)
enc.writeBits((int)k, (uint)(c + ((1 << (int)k) - 1)));
}
else // then c is in the interval [ 2^(k-1) + 1 ... 2^k ]
{
// so we translate c into the interval [ 2^(k-1) ... + 2^k - 1 ] by subtracting 1
enc.writeBits((int)k, (uint)(c - 1));
}
}
}
else // then c is 0 or 1
{
Debug.Assert((c == 0) || (c == 1));
enc.writeBit((uint)c);
}
#else // COMPRESS_ONLY_K
if (k != 0) // then c is either smaller than 0 or bigger than 1
{
Debug.Assert((c != 0) && (c != 1));
if (k < 32)
{
// translate the corrector c into the k-bit interval [ 0 ... 2^k - 1 ]
if (c < 0) // then c is in the interval [ - (2^k - 1) ... - (2^(k-1)) ]
{
// so we translate c into the interval [ 0 ... + 2^(k-1) - 1 ] by adding (2^k - 1)
c += ((1 << (int)k) - 1);
}
else // then c is in the interval [ 2^(k-1) + 1 ... 2^k ]
{
// so we translate c into the interval [ 2^(k-1) ... + 2^k - 1 ] by subtracting 1
c -= 1;
}
if (k <= bits_high) // for small k we code the interval in one step
{
// compress c with the range coder
enc.encodeSymbol(mCorrector[k], (uint)c);
}
else // for larger k we need to code the interval in two steps
{
// figure out how many lower bits there are
int k1 = (int)k - (int)bits_high;
// c1 represents the lowest k-bits_high+1 bits
c1 = (uint)(c & ((1 << k1) - 1));
// c represents the highest bits_high bits
c = c >> k1;
// compress the higher bits using a context table
enc.encodeSymbol(mCorrector[k], (uint)c);
// store the lower k1 bits raw
enc.writeBits(k1, c1);
}
}
}
else // then c is 0 or 1
{
Debug.Assert((c == 0) || (c == 1));
enc.encodeBit(mCorrectorBit, (uint)c);
}
#endif // COMPRESS_ONLY_K
}
// Encode a symbol with modelling
public void encodeSymbol(ArithmeticModel m, uint sym)
{
Debug.Assert(m!=null);
Debug.Assert(sym<=m.last_symbol);
uint x, init_interval_base=interval_base;
// compute products
if(sym==m.last_symbol)
{
x=m.distribution[sym]*(length>>DM.LengthShift);
interval_base+=x; // update interval
length-=x; // no product needed
}
else
{
x=m.distribution[sym]*(length>>=DM.LengthShift);
interval_base+=x; // update interval
length=m.distribution[sym+1]*length-x;
}
if(init_interval_base>interval_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
}
public void initSymbolModel(ArithmeticModel m, uint[] table=null)
{
m.init(table);
}
// Decode a symbol with modelling
public uint decodeSymbol(ArithmeticModel m)
{
uint n, sym, x, y=length;
if(m.decoder_table!=null)
{ // use table look-up for faster decoding
uint dv=value/(length>>=DM.LengthShift);
uint 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
uint 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;
uint k=(n=m.symbols)>>1;
// decode via bisection search
do
{
uint 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
Debug.Assert(sym<m.symbols);
return sym;
}
// Decode a symbol with modelling
public uint decodeSymbol(ArithmeticModel m)
{
uint n, sym, x, y = length;
if (m.decoder_table != null)
{ // use table look-up for faster decoding
uint dv = value / (length >>= DM.LengthShift);
uint 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
uint 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;
uint k = (n = m.symbols) >> 1;
// decode via bisection search
do
{
uint 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
}
Debug.Assert(sym < m.symbols);
return(sym);
}
public void initSymbolModel(ArithmeticModel m, uint[] table = null)
{
m.init(table);
}