zig/lib/std/os/linux/xtensa.zig

const builtin = @import("builtin");
const std = @import("../../std.zig");
const SYS = std.os.linux.SYS;

pub const syscall_arg_t = u32;

pub fn syscall0(
    number: SYS,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
        : .{ .memory = true });
}

pub fn syscall1(
    number: SYS,
    arg1: syscall_arg_t,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
          [arg1] "{a6}" (arg1),
        : .{ .memory = true });
}

pub fn syscall2(
    number: SYS,
    arg1: syscall_arg_t,
    arg2: syscall_arg_t,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
          [arg1] "{a6}" (arg1),
          [arg2] "{a3}" (arg2),
        : .{ .memory = true });
}

pub fn syscall3(
    number: SYS,
    arg1: syscall_arg_t,
    arg2: syscall_arg_t,
    arg3: syscall_arg_t,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
          [arg1] "{a6}" (arg1),
          [arg2] "{a3}" (arg2),
          [arg3] "{a4}" (arg3),
        : .{ .memory = true });
}

pub fn syscall4(
    number: SYS,
    arg1: syscall_arg_t,
    arg2: syscall_arg_t,
    arg3: syscall_arg_t,
    arg4: syscall_arg_t,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
          [arg1] "{a6}" (arg1),
          [arg2] "{a3}" (arg2),
          [arg3] "{a4}" (arg3),
          [arg4] "{a5}" (arg4),
        : .{ .memory = true });
}

pub fn syscall5(
    number: SYS,
    arg1: syscall_arg_t,
    arg2: syscall_arg_t,
    arg3: syscall_arg_t,
    arg4: syscall_arg_t,
    arg5: syscall_arg_t,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
          [arg1] "{a6}" (arg1),
          [arg2] "{a3}" (arg2),
          [arg3] "{a4}" (arg3),
          [arg4] "{a5}" (arg4),
          [arg5] "{a8}" (arg5),
        : .{ .memory = true });
}

pub fn syscall6(
    number: SYS,
    arg1: syscall_arg_t,
    arg2: syscall_arg_t,
    arg3: syscall_arg_t,
    arg4: syscall_arg_t,
    arg5: syscall_arg_t,
    arg6: syscall_arg_t,
) u32 {
    return asm volatile ("syscall"
        : [ret] "={a2}" (-> u32),
        : [number] "{a2}" (@intFromEnum(number)),
          [arg1] "{a6}" (arg1),
          [arg2] "{a3}" (arg2),
          [arg3] "{a4}" (arg3),
          [arg4] "{a5}" (arg4),
          [arg5] "{a8}" (arg5),
          [arg6] "{a9}" (arg6),
        : .{ .memory = true });
}

pub fn clone() callconv(.naked) u32 {
    // __clone(func, stack, flags, arg, ptid, tls, ctid)
    //         a2,   a3,    a4,    a5,  a6,   a7,  +16
    //
    // syscall(SYS_clone, flags, stack, ptid, tls, ctid)
    //         a2         a6,    a3,    a4,   a5,  a8
    asm volatile (
        \\ entry sp, 16
        \\
        \\ movi a8, -16
        \\ and a3, a3, a8
        \\
        \\ mov a9, a2
        \\ mov a10, a5
        \\
        \\ mov a5, a7
        \\ mov a8, a6
        \\ mov a6, a4
        \\ mov a4, a8
        \\ l32i a8, sp, 16
        \\ movi a2, 116 // SYS_clone
        \\ syscall
        \\
        \\ beqz a2, 1f
        \\ // parent
        \\ retw
        \\
        \\ // child
        \\1:
        \\ movi a7, 0
        \\ movi a0, 0
        \\
        \\ mov a2, a10
        \\ callx0 a9
        \\ movi a2, 118 // SYS_exit
        \\ syscall
    );
}

pub const restore = restore_rt;

pub fn restore_rt() callconv(.naked) noreturn {
    switch (builtin.zig_backend) {
        .stage2_c => asm volatile (
            \\ movi a2, %[number]
            \\ syscall
            :
            : [number] "I" (@intFromEnum(SYS.rt_sigreturn)),
        ),
        else => asm volatile (
            \\ syscall
            :
            : [number] "{a2}" (@intFromEnum(SYS.rt_sigreturn)),
        ),
    }
}

pub const VDSO = void;

pub const time_t = i32;