#include <mlibc/all-sysdeps.hpp>
#include <mlibc/thread-entry.hpp>

#include <bits/ensure.h>
#include <mlibc/tcb.hpp>

#include <sys/mman.h>

#include <stddef.h>
#include <stdint.h>

extern "C" void __mlibc_enter_thread(void *entry, void *user_arg, Tcb *tcb) {
    // Wait until our parent sets up the TID:
    while (!__atomic_load_n(&tcb->tid, __ATOMIC_RELAXED))
        mlibc::sys_futex_wait(&tcb->tid, 0, nullptr);

    if (mlibc::sys_tcb_set(tcb))
        __ensure(!"sys_tcb_set() failed");

    tcb->invokeThreadFunc(entry, user_arg);

    auto self = reinterpret_cast<Tcb *>(tcb);

    __atomic_store_n(&self->didExit, 1, __ATOMIC_RELEASE);
    mlibc::sys_futex_wake(&self->didExit);

    mlibc::sys_thread_exit();
}

namespace mlibc {

static constexpr size_t default_stacksize = 0x1000000;

int sys_prepare_stack(void **stack, void *entry, void *user_arg, void *tcb,
                      size_t *stack_size, size_t *guard_size, void **stack_base) {
    if (!*stack_size)
        *stack_size = default_stacksize;
    *guard_size = 0;

    if (*stack) {
		*stack_base = *stack;
    } else {
        *stack_base = mmap(nullptr, *stack_size, PROT_READ | PROT_WRITE,
                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    }
	
	uintptr_t *sp = reinterpret_cast<uintptr_t *>(reinterpret_cast<uintptr_t>(*stack_base) + *stack_size);

    *--sp = reinterpret_cast<uintptr_t>(tcb);
    *--sp = reinterpret_cast<uintptr_t>(user_arg);
    *--sp = reinterpret_cast<uintptr_t>(entry);
    *stack = reinterpret_cast<void *>(sp);
    return 0;
}
} // namespace mlibc