[cairo] Some other bits...

[Bill Spitzak]

Behdad Esfahbod wrote:

int
  _cairo_fixed_integer_part (cairo_fixed_t f)
  {
-    return f >> 16;
+    return f >> CAIRO_FIXED_FLOAT_BITS;
  }

  int
  _cairo_fixed_integer_floor (cairo_fixed_t f)
  {
      if (f >= 0)
-	return f >> 16;
+	return f >> CAIRO_FIXED_FLOAT_BITS;
      else
-	return -((-f - 1) >> 16) - 1;
+	return -((-f - 1) >> CAIRO_FIXED_FLOAT_BITS) - 1;
  }

These functions return identical values! I.e. integer_part() is 
returning floor(), in a much more efficient way.

Test program that exits with zero:

int main() {
   int f; for (f = -1; f > -0x7fffffff; f--) {
     int a,b;
     a = f>>16;
     b = -((-f-1)>>16)-1;
     if (a != b) {printf("%x %x %x\n", f, a,b); return 1;}
   }
   return 0;
}

I recommend you make the functions identical.

Rounding toward zero is complicated, but of absolutly no interest for 
graphics programs, so there is no reason to implement it.