coroutine cpp

coroutine_demo.cpp

#include <stdio.h>
#include <ucontext.h>
#include <list>

static void one();
static void two();
static void three();

static ucontext_t ctx1;
static ucontext_t ctx2;
static ucontext_t ctx3;

static char stack1[4096];
static char stack2[8192];

int main(int argc, char *argv[])
{
    printf("main start...\n");

    //create three() context
    getcontext(&ctx1);
    ctx1.uc_stack.ss_sp = stack1;
    ctx1.uc_stack.ss_size = sizeof(stack1);
    ctx1.uc_link = &ctx3;//ctx3 after ctx1.
    makecontext(&ctx1, three, 0);

    //create two() context
    getcontext(&ctx2);
    ctx2.uc_stack.ss_sp = stack2;
    ctx2.uc_stack.ss_size = sizeof(stack2);
    ctx2.uc_link = &ctx1;//ctx1 after ctx2.
    makecontext(&ctx2, two, 0);

    one();
    printf("main end...\n");
    return 0;
}

void one()
{
    printf("%s start...\n", __func__);
    //swift to ctx2, save current state in ctx3.
    swapcontext(&ctx3, &ctx2);

    printf("%s end...\n", __func__);
}

void two()
{
    printf("%s\n", __func__);
}

void three()
{
    printf("%s\n", __func__);
}