//! System runtime

pub const start = @import("start.zig");

comptime {
    _ = start;
}

pub const Invocation = enum(u64) {
    exit = 0x01,
    attach = 0x02,
    seal = 0x03,
    view = 0x04,
    mark = 0x05,
    spawn = 0x06,
    wait = 0x07,
    yield = 0x08,
    getkeychar = 0x09,
    viewstack = 0x0A,
    getlocation = 0x0B,
    setlocation = 0x0C,
    postman = 0x0D,
    wipe = 0x0E,
    cpuinfo = 0x0F,
    meminfo = 0x10,
    uptime = 0x11,
    gettime = 0x12,
    diskinfo = 0x13,
    reap = 0x14,
};

pub inline fn syscall(invocation: Invocation, args: anytype) u64 {
    const Args = @TypeOf(args);
    const fields = @typeInfo(Args).@"struct".fields;

    const arg0: u64 = if (fields.len > 0) toU64(args[0]) else 0;
    const arg1: u64 = if (fields.len > 1) toU64(args[1]) else 0;
    const arg2: u64 = if (fields.len > 2) toU64(args[2]) else 0;
    const arg3: u64 = if (fields.len > 3) toU64(args[3]) else 0;
    const arg4: u64 = if (fields.len > 4) toU64(args[4]) else 0;
    const arg5: u64 = if (fields.len > 5) toU64(args[5]) else 0;

    return asm volatile ("syscall"
        : [ret] "={rax}" (-> u64),
        : [number] "{rax}" (@intFromEnum(invocation)),
          [arg0] "{rdi}" (arg0),
          [arg1] "{rsi}" (arg1),
          [arg2] "{rdx}" (arg2),
          [arg3] "{r10}" (arg3),
          [arg4] "{r8}" (arg4),
          [arg5] "{r9}" (arg5),
        : .{ .rcx = true, .r11 = true, .memory = true });
}

inline fn toU64(value: anytype) u64 {
    const T = @TypeOf(value);
    return switch (@typeInfo(T)) {
        .int, .comptime_int => @intCast(value),
        .pointer => @intFromPtr(value),
        .@"enum" => @intFromEnum(value),
        else => @bitCast(value),
    };
}