www.pudn.com > XvidQP.rar > bit_res.cpp

/* bit_res.cpp 
 
	Implementation of Bit Reservoir for Layer III 
 
   Adapted from the public c code by Jeff Tsay. */ 
 
#include "all.h" 
#include "bit_res.h" 
 
Bit_Reserve::Bit_Reserve() 
{ 
	uint32 shifted_one = 1; 
 
	offset       = 0; 
   totbit		 = 0; 
   buf_byte_idx = 0; 
	buf          = new uint32[BUFSIZE]; 
	buf_bit_idx  = 8; 
	putmask      = new uint32[32]; 
 
   putmask[0] = 0; 
 
   for (int32 i=1; i<32; i++) 
   { 
   	putmask[i] = putmask[i-1] + shifted_one; 
      shifted_one <<= 1; 
   } 
} 
 
Bit_Reserve::~Bit_Reserve () 
{ 
	delete [] putmask; 
	delete [] buf; 
} 
 
uint32 Bit_Reserve::hgetbits(uint32 N) 
// read N bits from the bit stream 
{ 
   totbit += N; 
 
   uint32 val = 0; 
   int32 j = N; 
 
   while (j > 0) { 
 
	  if (buf_bit_idx == 0) { 
   	  buf_bit_idx = 8; 
	     buf_byte_idx++; 
/*	if (buf_byte_idx > offset) 
	  { printf("Buffer overflow !!\n");exit(3); } */ 
     } 
 
	  int32 k = (j < buf_bit_idx) ? j : buf_bit_idx; 
 
   // BUFSIZE = 4096 = 2^12, so 
   // buf_byte_idx%BUFSIZE == buf_byte_idx & 0xfff 
     int32 tmp = buf[buf_byte_idx & 0xfff] & putmask[buf_bit_idx]; 
     buf_bit_idx -= k; 
	  tmp = tmp >> buf_bit_idx; 
     j -=k; 
     val |= tmp << j; 
   } 
   return val; 
} 
 
uint32 Bit_Reserve::hget1bit() 
// read 1 bit from the bit stream 
{ 
   uint32 val; 
 
   totbit++; 
 
	if (buf_bit_idx == 0) { 
     buf_bit_idx = 8; 
	  buf_byte_idx++; 
   } 
 
   // BUFSIZE = 4096 = 2^12, so 
   // buf_byte_idx%BUFSIZE == buf_byte_idx & 0xfff 
   val = buf[buf_byte_idx & 0xfff] & putmask[buf_bit_idx]; 
   buf_bit_idx--; 
	val = val >> buf_bit_idx; 
 
   return val; 
} 
 
void Bit_Reserve::hputbuf(int32 val) 
// write 8 bits into the bit stream 
{ 
   buf[offset] = val; 
   offset = (offset + 1) & 0xfff; 
} 
 
void Bit_Reserve::rewindNbits(int32 N) 
{ 
	totbit -= N; 
	buf_bit_idx += N; 
	while(buf_bit_idx >= 8) { 
   	buf_bit_idx -= 8; 
		buf_byte_idx--; 
	} 
} 
 
void Bit_Reserve::rewindNbytes(int32 N) 
{ 
   totbit -= (N << 3); 
	buf_byte_idx -= N; 
}