mmap

pub fn mmap(address: ?[*]u8, length: usize, prot: PROT, flags: MAP, fd: fd_t, offset: off_t) usize {
    if (@hasField(SYS, "mmap2")) {
        return syscall6(
            .mmap2,
            @intFromPtr(address),
            length,
            @as(u32, @bitCast(prot)),
            @as(u32, @bitCast(flags)),
            @as(u32, @bitCast(fd)),
            @truncate(@as(u64, @bitCast(offset)) / mmap2Unit()),
        );
    } else {
        // The s390x mmap() syscall existed before Linux supported syscalls with 5+ parameters, so
        // it takes a single pointer to an array of arguments instead.
        return if (native_arch == .s390x) syscall1(
            .mmap,
            @intFromPtr(&[_]usize{
                @intFromPtr(address),
                length,
                @as(u32, @bitCast(prot)),
                @as(u32, @bitCast(flags)),
                @as(u32, @bitCast(fd)),
                @as(u64, @bitCast(offset)),
            }),
        ) else syscall6(
            .mmap,
            @intFromPtr(address),
            length,
            @as(u32, @bitCast(prot)),
            @as(u32, @bitCast(flags)),
            @as(u32, @bitCast(fd)),
            @as(u64, @bitCast(offset)),
        );
    }
}