bit存储读取方法

一般为了节省内存，一个unsigned char占8bit，分bit进行存储。存储时单个bit对外可以使用bool值，多个连续的bit可以使用unsigned char。

获取/设置单个bit值方法

获取/设置多个连续bit值方法

static bool getBitValue(unsigned char data, unsigned char bit)
{
  return (data >> bit) & 1;  
}

static void setBitValue(unsigned char &data, bool value, unsigned char bit)
{
      if(value)
      {
         data |= (1u << bit);
      }      
      else
      {
         data &= ~(1u << bit);
      }
}        

static unsigned char getRangeBitValue(unsigned char data, unsigned char lower_bit, unsigned char high_bit)
{
      data = data & ((1 << (high_bit + 1)) - 1);
      data = data >> lower_bit;
      return data;
}

static void setRangeBitValue(unsigned char &data,unisgned char value, unisgned char lower_bit, unsigned char high_bit)
{
      value << lower_bit;

      unsigned char mask = (1 << (high_bit + 1)) -1;
      mask = mask & ~((1 << lower_bit) - 1);

      value &= mask;
      data &= ~mask;
      data |= value;
}