code warrior disassemble code question

[lvyang]

code warrior IDE(5.9.0)

MCU:SPC560P34

e_stwu   rsp,-32(rsp)

I find this code on every function disassemble code first line.

who can tell me what's the meaning or reference doc?

Thanks.

[martin_kovar · Accepted solution]

Hi,

this instruction allocates stack for the function. At the end of the function, there is something like se_addi r1,0x20 which returns stack pointer to the previous position (before function was called).

Regards,

Martin

[lvyang]

Hi Martin,

Does the compile define the symble "rsp" as a stack pointer?

If so how to realize push and pop function.

Thanks in advance.

[martin_kovar]

Hello,

rsp is only (compiler) symbolic name for r1 register. If you look at the PPC EABI standard, you will find there that r1 register is always stack pointer.

What do you mean by push and pop functions?

If you create and call function in C language, compiler automatically create stack frame for this function.

But you can use nofralloc directive in your asm function:

Regards,

Martin

[lvyang]

Thanks a lot.