[HeliumHydride]

With GNU extensions, you can make a simpler coroutine macro without switch/case abuse:

    #define CO_BEGIN static void* cr_state_ = &&cr_st_0; goto *cr_state_; cr_st_0:
    #define CO_RETURN(x) ({ __label__ resume; cr_state_ = &&resume; return (x); resume:; })

[eqvinox]

Whether this is "simpler"… debatable ;D