 $  type coroutines.c

/* Coroutines */

#include <setjmp.h>

struct coroutine
{
    jmp_buf *calling;
    jmp_buf *env;
};

#if 0
int start_coroutine (struct coroutine *cr,
    int (*f) (void *p, struct coroutine *cr),
    void *p, int *stack)
{
int x, y;
struct coroutine calling;
    x = setjmp (*(cr->calling));
    if (x == 0)
    {
        calling.calling = cr->env;
        calling.env = cr->calling;
        /* _SP = stack; */
        y = (*f) (p, &calling);
    }
    else
        return x;
}
#endif

int call_coroutine (struct coroutine *cr, int entree)
{
int x;
    x = setjmp (*(cr->calling));
    if (x == 0)
    {
        my_longjmp (*(cr->env), entree);
        printf ("Error calling coroutine\n");
    }
    else
        return x;
}

int coroutine1 (char *p, struct coroutine *calling)
{
int x;
    printf ("Lancement coroutine avec parametre <%s>\n", p);
    x = call_coroutine (calling, (int)"1er parametre coroutine->appelant");
    printf ("Appelant retourne <%s> la 1ere fois\n", x);
    x = call_coroutine (calling, (int)"2eme parametre coroutine->appelant");
    printf ("Appelant retourne <%s> la 2eme fois\n", x);
    x = call_coroutine (calling, (int)"3eme parametre coroutine->appelant");
}

test_coroutine ()
{
struct coroutine cr;
jmp_buf calling, env;
#define STACK_SIZE 1000
int stack[STACK_SIZE];
int x;
    cr.calling = &calling;
    cr.env = &env;
    x = start_coroutine (&cr, coroutine1, (int)"Parametre lancement",
            stack + STACK_SIZE);
    printf ("Lancement retourne <%s>\n", x);
    x = call_coroutine (&cr, (int)"1er appel");
    printf ("1er appel retourne <%s>\n", x);
    x = call_coroutine (&cr, (int)"2eme appel");
    printf ("2eme appel retourne <%s>\n", x);
}

main ()
{
    test_coroutine ();
}

 $  type start_coroutine.mar

        .entry start_coroutine, ^m<>
        subl2 #20, sp
        nop
        pushl #8
        calls #1, MALLOC
        movl r0, -16(fp)
        moval @4(ap), r0
        moval @0(r0), r0
        nop
        pushal (r0)
        calls #1, SETJMP
        movl r0, -8(fp)
        tstl -8(fp)
        bneq sym.1
        movl 4(ap), r0
        movl 4(r0), @-16(fp)
        movl -16(fp), r1
        moval @4(ap), r0
        movl (r0), 4(r1)
        movl 16(ap), sp
        nop
        pushl -16(fp)
        nop
        pushl 12(ap)
        moval @8(ap), r0
        calls #2, (r0)
        movl r0, -12(fp)
        brb sym.2
        tstl r0
        nop
sym.1:
        movl -8(fp), r0
        ret
sym.2:
        ret
        .end

 $   cc /debug /noopt coroutines
 $ macro start_coroutine
 $ link /debug coroutines, start_coroutine
%LINK-W-NUDFSYMS, 1 undefined symbol:
%LINK-I-UDFSYM,         MY_LONGJMP 
%LINK-W-USEUNDEF, undefined symbol MY_LONGJMP referenced
        in psect $CODE offset %X00000031
        in module COROUTINES file VENUS$DUA1:[JACQUES.D1.COROUTINES]COROUTINES.O
BJ;9
 $ dir *.mar

Directory VENUS$DUA1:[JACQUES.D1.COROUTINES]

MY_LONGJMP.MAR;7    MY_LONGJMP1.MAR;1   MY_LONGJMP3.MAR;1   
START_COROUTINE.MAR;14                  START_COROUTINE1.MAR;1
START_COROUTINE_010894.MAR;1            _LONGJMP.MAR;2      

Total of 7 files.
 $ macro my_longjmp
 $ type my_longjmp.mar

        .entry my_longjmp, ^m<r2,r3>
        movl 4(ap), r0
        movl (r0)+, r2
        movq (r0)+, r2
        movq (r0)+, r4
        movq (r0)+, r6
        movq (r0)+, r8
        movq (r0)+, r10
        movl 4(r0), fp
        pushl 8(r0)
        pushl 12(r0)
        pushl 8(ap)
        movl (r0), ap
        popl r0
        popl r1
        popl sp
        jmp (r1)
        .end

 $ link /debug coroutines, start_coroutine, my_longjmp
 $  run /nodeb coroutines
Lancement coroutine avec parametre <Parametre lancement>
Lancement retourne <1er parametre coroutine->appelant>
Appelant retourne <1er appel> la 1ere fois
1er appel retourne <2eme parametre coroutine->appelant>
Appelant retourne <2eme appel> la 2eme fois
2eme appel retourne <3eme parametre coroutine->appelant>
 $
