Parser.h

#pragma once
 
#include <assert.h>
#include <stdint.h>
#include <stddef.h>
 
namespace Cogs::Core{
 
inline uint32_t get_bit(const uint8_t *data, size_t &bit)
{
  size_t byte = bit>>0x3; //size_t byte = bit/8;
  size_t n = bit&0x7; // size_t n = bit%8;
  uint32_t res = (data[byte]>>(7-n))&1;
  bit++;
  return res;
}
inline uint32_t peek_bit(const uint8_t *data, size_t &bit)
{
  size_t byte = bit>>0x3; //size_t byte = bit/8;
  size_t n = bit&0x7; //size_t n = bit%8;
  uint32_t res = (data[byte]>>(7-n))&1;
  return res;
}
inline uint32_t next_bits(size_t n, const uint8_t *data, size_t bit)
{
  assert(n<=32);
  uint32_t res = 0;
  for(uint32_t i=0; i<n; i++)
    res = (res << 1) | get_bit(data, bit);
  return res;
}
inline uint32_t read_bits(size_t n, const uint8_t *data, size_t &bit)
{
  assert(n<=32);
  uint32_t res = 0;
  for(uint32_t i=0; i<n; i++)
    res = (res << 1) | get_bit(data, bit);
  return res;
}
inline uint64_t read_bits64(size_t n, const uint8_t *data, size_t &bit)
{
  assert(n<=64);
  uint64_t res = 0;
  for(uint32_t i=0; i<n; i++)
    res = (res << 1) | get_bit(data, bit);
  return res;
}
 
// Parse Syntax Elements
inline uint32_t parse_ue(const uint8_t *data, size_t &bit);
 
inline uint32_t parse_ae(const uint8_t * /*data*/, size_t & /*bit*/)
{
  assert(false);
  return 0;
}
inline uint32_t parse_b(size_t n, const uint8_t *data, size_t &bit) { return read_bits(n, data, bit); }
inline uint32_t parse_f(size_t n, const uint8_t *data, size_t &bit) { return read_bits(n, data, bit); }
inline int32_t parse_i(size_t n, const uint8_t *data, size_t &bit) { return (int32_t)read_bits(n, data, bit); }
inline int32_t parse_se(const uint8_t *data, size_t &bit)
{
  uint32_t codeNum = parse_ue(data, bit);
  uint32_t neg = (codeNum & 1) ^ 1;
  return -(int32_t)neg * (((int32_t)codeNum+1)/2);
}
inline uint32_t parse_u(size_t n, const uint8_t *data, size_t &bit) { return read_bits(n, data, bit); }
inline uint64_t parse_u64(size_t n, const uint8_t *data, size_t &bit) { return read_bits64(n, data, bit); }
inline uint32_t parse_ue(const uint8_t *data, size_t &bit)
{
  int32_t leadingZeroBits = -1;
  for(uint32_t b=0; !b; leadingZeroBits++)
    b = get_bit(data, bit);
  //uint32_t codeNum = (1<<leadingZeroBits)-1+readBits(leadingZeroBits);
  uint32_t codeNum = (1<<leadingZeroBits)-1+parse_u(leadingZeroBits, data, bit);
  return codeNum;
}
inline uint32_t parse_ue(const uint8_t *data, size_t &bit, size_t size)
{
  int32_t leadingZeroBits = -1;
  for(uint32_t b=0; !b; leadingZeroBits++){
    b = get_bit(data, bit);
    if(bit/8 >= size) return 0;
  }
  //uint32_t codeNum = (1<<leadingZeroBits)-1+readBits(leadingZeroBits);
  uint32_t codeNum = (1<<leadingZeroBits)-1+parse_u(leadingZeroBits, data, bit);
  return codeNum;
}
inline uint64_t parse_ue64(const uint8_t *data, size_t &bit)
{
  int32_t leadingZeroBits = -1;
  for(uint32_t b=0; !b; leadingZeroBits++)
    b = get_bit(data, bit);
  //uint32_t codeNum = (1<<leadingZeroBits)-1+readBits(leadingZeroBits);
  uint64_t codeNum = ((uint64_t)1<<leadingZeroBits)-1+parse_u64(leadingZeroBits, data, bit);
  return codeNum;
}
 
inline uint32_t more_rbsp_data(const uint8_t *data, size_t size, size_t bit)
{
  if(bit>=size*8) return 0x0;
  size_t stop_bit = size*8-1;
  while(!peek_bit(data, stop_bit)) stop_bit--;
  if(bit<stop_bit) return 0x1;
  return 0x0;
}
 
}// namespace ...