Function encode_upcall_trd104_ptr 

pub unsafe fn encode_upcall_trd104_ptr(
    upcall: &FunctionCall,
    a0: *mut u32,
    a1: *mut u32,
    a2: *mut u32,
    a3: *mut u32,
)

Encode the upcall arguments into 4 registers compatible with TRD104.

Use pointer writes.

Safety

All pointers a0, a1, a2, a3 must point to valid, aligned, and writable memory locations.