#include <u.h>
#include <base.h>

// -----------------------------------------------------------------------
// Assembly routines

extern void    _newcoro(Coro *co, uintptr (*func)(Coro*, uintptr), void *stk);
extern uintptr _coroyield(Coro *co, uintptr arg);

// -----------------------------------------------------------------------
// Globals

// static thread_local coro *CONTEXT;

// -----------------------------------------------------------------------
// C interface

/* Co-routine context */
struct Coro 
{
    void*   sp;
    void*   bp;
    uintptr size;
    void*   user;
};

Coro*
coro·make(uintptr stk, uintptr (*func)(Coro*, uintptr))
{
    if (!func) return nil;
    if (stk == 0) stk = 8192;

    byte *block = malloc(stk);
    Coro *co    = (Coro*)&block[stk - sizeof(Coro)];
    co->bp      = block;
    co->size    = stk;

    _newcoro(co, func, co);
    return co;
}

error
coro·free(Coro *co)
{
    enum 
    {
        NIL,
        GOOD,
        EMPTY,
        LOST,
    };

    if (!co)           return NIL;
    if (!co->bp)       return LOST;
    if (co->size == 0) return EMPTY;

    free(co->bp);

    return GOOD;
}

uintptr
coro·yield(Coro *c, uintptr arg)
{
    return _coroyield(c, arg);
}