[Ether]

Originally Posted by jhersh

Floating point operations ... are done in the PPC core's FPU. You can look at the details for it here: http://cache.freescale.com/files/32b...e300coreRM.pdf

Edit: FP instructions are in section 3.2.4.2 (pg 119).

Thanks for the link Joe.

Using two fmadds instructions¹, at one cycle each², you can get arctangent(x) in the first octant accurate to +/- 0.25 degrees. Pretty tough to beat with a lookup table.

Wrap 3 compares, 1 divide, and 1 more add around that, and you've got atan2(y,x) accurate to +/- 0.25 degrees good for all four quadrants.



¹Para 3.2.4.2.2 Table 3-9

²Para 1.1