In a C compiler implemented for that architecture, copying a value of memory line size could very well use an instruction that does it all at once if the regist

In a C compiler implemented for that architecture, copying a value of memory line size could very well use an instruction that does it all at once if the registers are large enough or a DMA intrinsic is exposed. Really that's the point. C is like a near-asm language that standardizes across ISAs with the opportunity for the compiler, libraries, or programmer to do something more clever on a specific system. It requires dedication and patience, but in the end is generally a good middle ground for low level work.