Allocates the space required to hold a new set of registers
on the stack given by stackPointer and clears the area
except the for the PC which is set to the address given by
entryPoint. The stack will be set so that when the
entryPoint function returns, the fallback function will be
called.
INPUTS
stackPointer
Pointer to specific stack.
entryPoint
Function to call when the new context
comes alive.
fallBack
Address of the function to be called
when the entryPoint function returns.
RESULT
The new stackPointer with the context saved.
NOTES
This function is very CPU dependant. In fact it can differ
over different models of the same processor family.