//! Syscall implementations for `riscv32`.

use super::{StatfsBuf, SysInfo, UtsNameBuf};

pub(super) unsafe fn sys_open(path: *const u8, flags: i32) -> i32 {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 56i32,  // SYS_openat
      in("a0") -100i32,  // AT_FDCWD
      in("a1") path,
      in("a2") flags,
      in("a3") 0i32,  // mode
      lateout("a0") ret,
      options(nostack)
    );
    ret
  }
}

pub(super) unsafe fn sys_read(fd: i32, buf: *mut u8, count: usize) -> isize {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 63i32,  // SYS_read
      in("a0") fd,
      in("a1") buf,
      in("a2") count,
      lateout("a0") ret,
      options(nostack)
    );
    ret as isize
  }
}

pub(super) unsafe fn sys_write(fd: i32, buf: *const u8, count: usize) -> isize {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 64i32,  // SYS_write
      in("a0") fd,
      in("a1") buf,
      in("a2") count,
      lateout("a0") ret,
      options(nostack)
    );
    ret as isize
  }
}

pub(super) unsafe fn sys_close(fd: i32) -> i32 {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 57i32,  // SYS_close
      in("a0") fd,
      lateout("a0") ret,
      options(nostack)
    );
    ret
  }
}

pub(super) unsafe fn sys_uname(buf: *mut UtsNameBuf) -> i32 {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 160i32,  // SYS_uname
      in("a0") buf,
      lateout("a0") ret,
      options(nostack)
    );
    ret
  }
}

pub(super) unsafe fn sys_statfs(path: *const u8, buf: *mut StatfsBuf) -> i32 {
  unsafe {
    // asm-generic __NR_statfs routes to sys_statfs64 on 32-bit: 3-arg form.
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 43i32,  // __NR_statfs
      in("a0") path,
      in("a1") core::mem::size_of::<StatfsBuf>(),
      in("a2") buf,
      lateout("a0") ret,
      options(nostack)
    );
    ret
  }
}

pub(super) unsafe fn sys_sysinfo(info: *mut SysInfo) -> i64 {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 179_i32, // __NR_sysinfo
      in("a0") info,
      lateout("a0") ret,
      options(nostack)
    );
    i64::from(ret)
  }
}

pub(super) unsafe fn sys_sched_getaffinity(
  pid: i32,
  mask_size: usize,
  mask: *mut u8,
) -> i32 {
  unsafe {
    let ret: i32;
    core::arch::asm!(
      "ecall",
      in("a7") 123i32,  // __NR_sched_getaffinity
      in("a0") pid,
      in("a1") mask_size,
      in("a2") mask,
      lateout("a0") ret,
      options(nostack)
    );
    ret
  }
}

pub(super) unsafe fn sys_exit(code: i32) -> ! {
  unsafe {
    core::arch::asm!(
      "ecall",
      in("a7") 93i32,  // SYS_exit
      in("a0") code,
      options(noreturn, nostack)
    );
  }
}