What is the fastest way to convert float to int on x86

Question

What is the fastest way you know to convert a floating-point number to an int on an x86 CPU. Preferrably in C or assembly (that can be in-lined in C) for any combination of

Answer 1

There is one instruction to convert a floating point to an int in assembly: use the FISTP instruction. It pops the value off the floating-point stack, converts it to an integer, and then stores at at the address specified. I don't think there would be a faster way (unless you use extended instruction sets like MMX or SSE, which I am not familiar with).

Another instruction, FIST, leaves the value on the FP stack but I'm not sure it works with quad-word sized destinations.