...
The context switch code is generally part of a processor’s port of µC/OS-III. A port is the code needed to adapt µC/OS-III to the desired processor. This code is placed in special C and assembly language files: os_cpu.h, os_cpu_c.c and os_cpu_a.asm. Porting µC/uC-OS-III provides more details on the steps needed to port µC/OS-III to different CPU architectures.
...