Note: lesser precision does not significantly reduce execution time.



      FPU Tag Word

      Bit 15                8                        0
      ┌──┬──┬──┬──┼──┬──┬──┬──┼──┬──┬──┬──┼──┬──┬──┬─┴┐
      │ x  x│ x  x│ x  x│ x  x│ x  x│ x  x│ x  x│ x  x│
      └──┴─┼┴──┴─┼┴──┴─┼┴──┴─┼┴──┴─┼┴──┴─┼┴──┴─┼┴──┴─┼┛
           7     6     5     4     3     2     1     0 Tag number

      The tag number 0 corresponds to the register which is
      currently ST0.
      The bits for each tag have the same meaning:

       0  0  Valid
       0  1  Zero
       1  0  Special (NaN,Infinity,Denormal,Unnormal,Unsupported)
       1  1  Empty




IIT bankswitching  (IIT math coprocessor)
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