符号/Sign 有效数M/Significand 指数E/Exponent
  .  
+   0.0   0
0x0000000000000000 0b0000000000000000000000000000000000000000000000000000000000000000
  .  
+   0.0   0
0x0000000000000000 0b0000000000000000000000000000000000000000000000000000000000000000
  .  
+   0.0   0
0x0000000000000000 0b0000000000000000000000000000000000000000000000000000000000000000