NAME
        afp - Convert ASCII string variable into fast floating point

   SYNOPSIS
        ffp_value = afp(string);

    FUNCTION
        Accepts the address of the ASCII string in C format that is
        converted into an FFP floating point number.

        The string is expected in this Format:
        {S}{digits}{'.'}{digits}{'E'}{S}{digits}
        <*******MANTISSA*******><***EXPONENT***>


        Syntax rules:
        Both signs are optional and are '+' or '-'. The mantissa must be
        present. The exponent need not be present. The mantissa may lead
        with a decimal point. The mantissa need not have a decimal point.
        Examples: All of these values represent the number fourty-two.
                     42            .042e3
                     42.          +.042e+03
                    +42.          0.000042e6
                0000042.00       420000e-4
                             420000.00e-0004

        Floating point range:
        Fast floating point supports the value zero and non-zero values
        within the following bounds -
                        18                             20
         9.22337177 x 10   > +number >        5.42101070 x 10
                        18                             -20
        -9.22337177 x 10   > -number > -2.71050535 x 10

        Precision:
        This conversion results in a 24 bit precision with guaranteed
        error less than or equal to one-half least significant bit.

        INPUTS
        string - Pointer to the ASCII string to be converted.


        OUTPUTS
        string - points to the character which terminated the scan
        equ - fast floating point equivalent