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/*
** nsvbs.h - NSV basic inline bitstream classes
**
** Copyright (C) 2001-2002 Nullsoft, Inc.
** Confidential Subject to NDA
**
** Note: these bitstream classes encode/decode everything in LSB.
** bits are stored from the lowest bit to the highest bit.
** putbits(4,0xE) will result in getbits(1)=0, getbits(1)=1,
** getbits(1)=1, getbits(1)=1
** or of course, getbits(4) == 0xE :)
*/
#ifndef _NSVBS_H_
#define _NSVBS_H_
#include <stdlib.h>
#include <memory.h>
#include <bfc/platform/types.h>
#include "../nu/GrowBuf.h"
class nsv_OutBS
{
public:
nsv_OutBS() { m_used = 0; m_curb=0; }
~nsv_OutBS() { }
void putbits(int nbits, unsigned int value)
{
while (nbits-- > 0)
{
m_curb|=(value&1)<<(m_used&7);
if (!((++m_used)&7))
{
m_bits.add(&m_curb,1);
m_curb=0;
}
value>>=1;
}
}
// lets you put in any amount of data, but does not preserve endianness.
void putdata(int nbits, void *data)
{
unsigned char *c=(unsigned char *)data;
if (!(m_used&7) && nbits >= 8)
{
m_bits.add(c,nbits/8);
c+=nbits/8;
m_used+=nbits&~7;
nbits&=7;
}
while (nbits > 0)
{
int tb=nbits;
if (tb > 8) tb=8;
putbits(tb,*c++);
nbits-=tb;
}
}
int getlen() { return m_used; } // in bits
void *get(int *len) // len is in bytes, forces to byte aligned.
{
if (m_used&7)
{
m_bits.add(&m_curb,1);
m_used=(m_used+7)&~7;
m_curb=0;
}
*len=m_used/8;
return m_bits.get();
}
void clear()
{
m_used=0;
m_curb=0;
m_bits.resize(0);
}
private:
GrowBuf m_bits;
int m_used; // bits
unsigned char m_curb;
};
class nsv_InBS {
public:
nsv_InBS() { m_bitpos=0; m_eof=0; }
~nsv_InBS() { }
void clear()
{
m_eof=0;
m_bitpos=0;
m_bits.resize(0);
}
void add(void *data, int len)
{
m_bits.add(data,len);
m_eof=0;
}
void addbyte(unsigned char byte)
{
add(&byte,1);
}
void addint(unsigned int dword)
{
addbyte(dword&0xff);
addbyte((dword>>8)&0xff);
addbyte((dword>>16)&0xff);
addbyte((dword>>24)&0xff);
}
void compact()
{
size_t bytepos=m_bitpos/8;
if (bytepos)
{
unsigned char *t=(unsigned char *)m_bits.get();
size_t l=m_bits.getlen()-bytepos;
memcpy(t,t+bytepos,l);
m_bits.resize(l);
m_bitpos&=7;
}
m_eof=0;
}
void seek(ptrdiff_t nbits)
{
if (nbits < 0 && ((size_t)(-nbits)) > m_bitpos)
m_bitpos=0;
else
m_bitpos+=nbits;
m_eof=m_bits.getlen()*8 < m_bitpos;
}
void rewind() { m_bitpos=0; m_eof=0; }
int eof() { return m_eof; }
size_t avail() { if (m_eof) return 0; return m_bits.getlen()*8 - m_bitpos; }
unsigned int getbits(size_t nbits)
{
unsigned int ret=0;
if (!nbits) return ret;
unsigned char *t=(unsigned char *)m_bits.get();
if (!t || m_bits.getlen()*8 < m_bitpos+nbits) m_eof=1;
else
{
t+=m_bitpos/8;
for (size_t sh = 0; sh != nbits; sh ++)
{
ret|=((*t>>(m_bitpos&7))&1) << sh;
if (!((++m_bitpos)&7)) t++;
}
}
return ret;
}
int getdata(size_t nbits, void *data)
{
unsigned char *t=(unsigned char *)data;
if (m_bits.getlen()*8 < m_bitpos+nbits) return 1;
if (!(m_bitpos&7) && nbits >= 8)
{
char *bitptr=(char*)m_bits.get();
bitptr+=(m_bitpos/8);
memcpy(t,bitptr,nbits/8);
m_bitpos+=nbits&~7;
t+=nbits/8;
nbits&=7;
}
while (nbits > 0)
{
size_t nb=nbits;
if (nb > 8) nb=8;
*t++=getbits(nb);
nbits-=nb;
}
return 0;
}
void *getcurbyteptr()
{
char *t=(char*)m_bits.get();
return (void *)(t+(m_bitpos/8));
}
private:
GrowBuf m_bits;
size_t m_bitpos;
int m_eof;
};
#endif//_NSVBS_H_
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