PRC wrote: > The MIPS ABI document says: > For non-leaf function,$31 must be saved. If any of > $16..$23 or$29..$31 is changed within the called function, it must be saved > in the stack frame before use and restored from the stack frame before re- > turn from the function. > > My interrupt/exception handler contains two parts: one written in assembly > and the other written in C. The ASM handler does some simple work like > saving status, epc and gerneral registers and then jumps/calls to the C handler > to do more complex work. Since MIPS ABI guarantees $16~$23 and $29~$31 are saved > in C functions if they are used, is it safe to save only those registers except $16~$23 and $29~$31 in ASM handler? In theory, yes: the ABI makes that guarantee. As long as all called code conforms to the ABI you'll be fine. Andrew.
