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