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| #include <stdio.h>
#include <string.h>
#include <setjmp.h>
#include <signal.h>
#include <unistd.h>
#include <sys/time.h>
#define STACK_SIZE 1024
#define TPROC 1024
#define NPROC 1024
#define SNONE 0
#define SRUN 1
#define SSLEEP 2
typedef struct
{
jmp_buf buffer;
char stack[STACK_SIZE];
int stack_size;
int flag;
} TProc;
static sigset_t set;
struct sigaction handler;
static char* top_stack;
static int elu;
static TProc processus[NPROC];
#define init_scheduler() \
char top; \
int i; \
do \
{ \
top_stack = ⊤ \
elu = 0; \
for (i = 0; i < NPROC; i++) \
{ \
processus[i].flag = SNONE; \
} \
} while (0)
int
mysetjmp (int index)
{
int old = index;
if (old >= NPROC)
{
return -1;
}
if (setjmp (processus[old].buffer) == 0)
{
processus[old].stack_size = top_stack - (char*) &old;
memcpy (processus[old].stack, &old, processus[old].stack_size);
}
else
{
char* start = top_stack - processus[elu].stack_size;
memcpy (start, processus[elu].stack, processus[elu].stack_size);
return 1;
}
return 0;
}
void
mylongjmp (int index)
{
if (index >= NPROC)
{
return ;
}
elu = index;
longjmp (processus[elu].buffer, 1);
}
static int
search_free_space (void)
{
int i;
for (i = 0; i < NPROC; i++)
{
if (processus[i].flag == SNONE)
{
return i;
}
}
return -1;
}
void
new_proc (void (*f)(void))
{
int new = search_free_space ();
if (new == -1)
{
return ;
}
processus[new].flag = SRUN;
if (mysetjmp (new) != 0)
{
f ();
}
}
int
election (void)
{
int i = elu;
i = (i + 1) % NPROC;
while (processus[i].flag != SRUN)
{
i = (i + 1) % NPROC;
}
return i;
}
void
commut (int u)
{
int next;
sigprocmask (SIG_BLOCK, &set, NULL);
next = election ();
if (mysetjmp (elu) == 0)
{
mylongjmp (next);
}
sigprocmask (SIG_UNBLOCK, &set, NULL);
}
void
start_sched (void)
{
sigemptyset (&set);
sigaddset (&set, SIGALRM);
sigemptyset (&(handler.sa_mask));
handler.sa_handler = commut;
handler.sa_flags |= SA_RESTART;
sigaction (SIGALRM, &handler, NULL);
ualarm (250000, 1000000);
commut (0);
}
void
f (void)
{
int n = 0;
while (1)
{
printf ("Execute f : %d\n", n++);
}
}
void
g (void)
{
int m = 0;
while (1)
{
printf ("Execute g : %d\n", m++);
}
}
int
main (void)
{
init_scheduler ();
new_proc (f);
new_proc (g);
start_sched ();
return 0;
} |
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