Question: #include #include #include #include jmp_buf trampoline, jb1, jb2; void thread1() { //while(1) { /* The following context-switches to the other thread. */ if (!setjmp(jb1)) {
#include
#include
#include
#include
jmp_buf trampoline, jb1, jb2;
void thread1()
{
//while(1) {
/* The following context-switches to the other thread. */
if (!setjmp(jb1)) {
printf("Step 8 ");
longjmp(jb2, 1);
/* NOTREACHED */
} else {
printf("Step 7 ");
}
// }
}
int thread2()
{
//while(1) {
/* The following context-switches to the other thread. */
if (!setjmp(jb2)) {
printf("Step 6 ");
longjmp(jb1, 1);
/* NOTREACHED */
} else {
printf("Step 9 ");
}
//}
}
void thread2_launchpad()
{
/* We create a new stack area for thread2 to run in by doing
* a dummy allocation of space (an array) on the stack.
* The reason for assigning 1 to the last element of the
* array is simply to avoid the compiler optimising away the
0 * array (as it would otherwise never be used).
*/
char space_for_thread[4096];
space_for_thread[4096-1] = 1;
printf("Step 5 ");
thread2();
}
int main(int argc, char* argv[])
{
printf("Step 1 ");
if (!setjmp(trampoline)) {
/* First return from trampoline - initialise. */
printf("Step 2 ");
if (!setjmp(jb1)) {
/* First return from setjmp snapshotting thread1 */
printf("Step 3 ");
/* Go to 2nd return of trampoline to create thread2 */
longjmp(trampoline, 1);
/* NOTREACHED */
} else {
/* We get here when we have been resumed
* by thread2 */
printf("Step 7 ");
thread1(); /* run thread1 */
}
} else {
/* Second return of trampoline caused by longjmp() above */
printf("Step 4 ");
thread2_launchpad(); /* launchpad for thread2 to
* run in distinct stack area */
}
}
Can you explain what this code does please?
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