mips calling conventions

[Nathan Sidwell]

Mad Props wrote:
> Hi,
> 
> I have a question regarding the mips32 calling conventions in gcc. I
> implement in C++ and use assembly when neccessary. As far as I know the
> first four arguments are passed in a0 to a3 but space on the stack still
> needs to be "allocated" for those four arguments. Here is what I've got so
> far:

this is true for integer args, I think (but I'm not sure) floating point args 
are passed differently.  The definitive answer would be in the mips psABI 
document (google is you friend).

> [...]
> mfc0    a0,c0_badvaddr
> subi    sp, sp, 16
> jal     a000a8e8 <foo>
> move    a1,sp  <-- not sure why you have this
> addi    sp, sp, 32
> [...]
> 
> every time a call a C routine in assembly.
Yes, you need to do this.  Though most of the time, you can just have the stack 
permanently depressed through out your function.  GCC does this for instance.

nathan

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