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Newsgroups: comp.lang.ada
Date: Mon, 17 Sep 2018 15:41:33 -0700 (PDT)
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Subject: Re: GNAT for AVR - Mathematical Functions
From: Aurele Vitali <aurele.vitali@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:54350
Date: 2018-09-17T15:41:33-07:00
List-Id: <comp.lang.ada>

I don't know anything about the ATmega328P, but if it uses a builtin floating point processor, you can use Ada inline floating point assembler.  Its not hard to do. Here is a simple example of the square root function: 

  with System.Machine_Code; use System.Machine_Code; 
  EOL : constant String := ASCII.LF & ASCII.HT;

  function Sqrt( x : in Long_Float ) return Long_Float is 
    Result : Long_Float := 0.0; 
  begin 
    Asm( ( "fldl  %1" & EOL &                 -- Load x in St(0) 
           "fsqrt   " & EOL &                 -- Take the Sqrt of St(0) 
           "fstpl %0" ),                      -- Store result and pop St(0) 
         Outputs => ( Long_Float'Asm_Output("=m", Result ) ), 
         Inputs  => ( Long_Float'Asm_Input ( "m",      x ) ) ); 
    return Result; 
  end Sqrt; 

You can do the same thing for trig functions...  Just cut and past and see if this example works. 

Cheers