First, I'm sorry for my English grammar..
I'v been trying to reduce the overhead caused by entering into an ISR.
One of the solutions is to save only a fraction of the CPU's registers.
In order to do that, while playing safe with the interrupted thread, I will have to make that the ISR will run using that fraction of the CPU's registers only.
Is there a way to order the compiler to use only some specific registers while compiling?
Important: I'm using Freescals's MPC5553...