Exercises in Emulation: Xbox 360’s FMA Instruction

I made some contributions to the team that taught the Xbox 360 how to emulate a lot of the original Xbox games – emulating x86 on PowerPC – and was given the job title Emulation Ninja for that work*. But if we don’t have FMA then we have to do the multiply, get 2349, which would be rounded to two digits of precision and get 2300 (2.3e3). Luckily the vast majority of floating-point math in games is done to float (32-bit) precision, and I was quite happy to use double (64-bit precision) instructions in the emulation of FMA.

Source: randomascii.wordpress.com