Floating Point and DSP Extensions
Writing float in C on a microcontroller does not tell you what the hardware will do. The same line of source can compile to one instruction, to a forty-cycle library call, or to a two-hundred-cycle double-precision emulation — and the compiler chooses silently, based on flags you may not have set deliberately. Nothing in the source distinguishes the three cases, which is why "why is my control loop suddenly missing deadlines" is so often a floating-point question.