Converting floating point to fixed point

Question

In C++, what\'s the generic way to convert any floating point value (float) to fixed point (int, 16:16 or 24:8)?

EDIT: For clarification, fixed-poin

Answer 1

There isn't any built in support in C++ for fixed point numbers. Your best bet would be to write a wrapper 'FixedInt' class that takes doubles and converts them.

As for a generic method to convert... the int part is easy enough, just grab the integer part of the value and store it in the upper bits... decimal part would be something along the lines of:

for (int i = 1; i <= precision; i++)
{
   if (decimal_part > 1.f/(float)(i + 1)
   {
      decimal_part -= 1.f/(float)(i + 1);
      fixint_value |= (1 << precision - i);
   }
}

although this is likely to contain bugs still