osblog/risc_v/ch7/src/syscall.rs

// syscall.rs
// System calls
// Stephen Marz
// 3 Jan 2020

use crate::cpu::TrapFrame;

pub fn do_syscall(mepc: usize, frame: *mut TrapFrame) -> usize {
    let syscall_number;
    unsafe {
        // A0 is X10, so it's register number 10.
        syscall_number = (*frame).regs[10];
    }
    match syscall_number {
        0 => {
            // Exit
            mepc + 4
        },
        _ => {
            print!("Unknown syscall number {}", syscall_number);
            mepc + 4
        }
    }
}